Go to Main Site Diff'rent Strokers
For fans of oddball two-strokes everywhere
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
Classic Bike Trackdays

My SDR...
Goto page 1, 2, 3  Next
 
Post new topic   Reply to topic    Diff'rent Strokers Forum Index -> Yamaha
View previous topic :: View next topic  
Author Message
James P



Joined: 31 Mar 2013
Posts: 121
Location: Sydney, Australia

PostPosted: Fri Mar 24, 2017 8:06 am    Post subject: My SDR... Reply with quote

I had wanted one of these for a long time – since 1991 in fact, after reading the article in the July edition of Performance Bikes magazine. Unfortunately, large-scale importing of secondhand bikes from Japan was unheard of in Australia at that time, so I reluctantly dismissed the idea of ever owning an SDR.
About 5 years later, importers began to bring in container loads of secondhand 4-cylinder 4-stroke 250s, but I didn’t see any SDRs. I think that a small number of them (probably no more than half-a-dozen) found their way to Perth in Western Australia in the late 1990s or early 2000s, but I only discovered this comparatively recently.

Fast-forward to 2012 and I discovered Old Gold Motorcycles on the outskirts of Sydney, specialising in pre-1989 motorcycles, including the import of same from Japan. I got in touch and asked about an SDR. Proprietor Steve said he had never heard of the SDR but would investigate. He later advised that good examples were difficult to obtain, but would see what he could do.

The SDR is comparatively rare. Although the Yamaha frame number catalogues show that frame numbers from 2TV-000101 to 2TV-025000 were reserved, my research suggests that fewer than 9000 were made. Informed sources in Japan state that they have never seen a frame number in the 2TV-009000 range or higher.
I can only conclude that the SDR was a flop when released, or that it quickly fell out of fashion with the Japanese bike-buying public at the time. The bike did enjoy some popularity in its time though, including a dedicated racing series called the SDR Cup. The SDR still has a small following in Japan, assisted by Yasuhiro Tanaka’s SDR200.com parts supply business (http://www.sdr200.com/). It would be interesting to know why Yamaha chose to release the bike for sale only in Japan.
As far as I have been able to tell, the SDR was first released in July 1987 in metallic green and metallic red. An additional colour (black with grey seat) was released in November of that same year. Although it was still being sold as a new model in 1988, I haven’t found any information confirming that SDRs were still being made after the end of 1987, which suggests that they were made for only about 6 months.
The black version was introduced at frame number 2TV-007701, but I’m not sure whether all SDRs from that point onwards were black or whether they were thereafter made in all 3 colours. I’m also not sure whether it is possible to discern a bike’s original colour without a dealer’s sales receipt or some kind of factory documentation. On introduction of the black version, the only parts that were changed from previous models were the ones that were coloured differently.
Something else of which I am unsure is whether Yamaha actually made SDRs with frame numbers all the way from 2TV-000101 up to 2TV-007700 before releasing the black version. From experience gained so far, it is possible that the initial production fell well short of frame number 2TV-007700 and Yamaha simply chose a convenient “future” starting number for frames of the black version.

Around late 2013, Steve told me he had secured a couple of SDRs; one was ready to be shipped and the other would follow shortly. A few photos suggested that the second one was in better condition than the first, although both were reasonably priced. I told him I would buy at least one of them!

The first one arrived and I went to have a look. It showed definite signs of neglect, but there was nothing that couldn’t be fixed. Since I had already paid a deposit, Steve agreed to wait for the second one to arrive before I had to make a decision.
The second one also showed signs of neglect, but was in much better condition generally. Unfortunately however, it came without a fuel tank, which is one of the more difficult parts to find. The better condition of the second bike made it a fairly easy decision. I almost bought both bikes, but concerns about available garage space forced me to choose only one. The SDR I bought is one of the first 300 units made.
Below are two photos of the bike as it arrived. The fuel tank was borrowed from the "other" SDR, so I could get the Australian Design Rules compliance certificate (it seems that bikes without fuel tanks don't comply with the ADRs Laughing ).






Some of the areas which needed attention were:

Corrosion – Many of the SDR’s aluminium castings were clear-coated from the factory. Without extreme care and thorough maintenance, air and moisture work their way under the coating via chips and scratches, leaving areas where the coating bubbles up, with white powder residue underneath. Just about every cast aluminium component on this bike exhibited some evidence of this type of corrosion. Even without corrosion, the clear coating turns slightly yellow with age, although I don’t necessarily consider this a problem if no corrosion exists.

Rust – Luckily there was very little rust on this bike (most of that was light surface rust), but I couldn’t tolerate some of it for purely aesthetic reasons. Items which I considered needed attention were parts of the frame, lower steering yoke, radiator grille, engine cradle, rear sub-frame, rear suspension linkage parts and assorted chassis fasteners. Luckily the fork stanchions were in good condition, with only a few blemishes outside of the “sealing” portion. As I would later discover, they were also straight, which was a bonus.

I wasn’t particularly worried whether the engine ran or not, but I did make sure to check that all 6 gears could be easily selected and that the engine turned over smoothly by the kickstart lever, with some feeling of compression. I also checked that the electrics worked from a battery. Everything seemed in order (including power valve cycling), although there was a short circuit at one of the indicators (but this was easily fixed).

I took delivery around the end of 2014 but couldn’t make an immediate start as I was still finishing off another project. However, I had already started the search for a fuel tank and whatever other parts I thought may be necessary or useful.
At that point in time, secondhand SDR parts were fairly easily available in Japan and were mostly quite cheap (although unfortunately neither of those two properties applied to fuel tanks!). I bought practically any secondhand SDR spare part I could find if it was serviceable and cheap. I eventually ended up with two fuel tanks; one with several dents and scrapes and the other with only minor blemishes. Importantly, both were solid and would need only the POR-15 treatment to make them usable.
I have noticed over the past 2-3 years that the price of secondhand parts in Japan has risen markedly. Most SDR parts are still obtainable with patience (even fuel tanks), but there seems to be a lot more buyer interest generally.


I already had a rough idea of what I wanted to achieve with my SDR. It would be of basically standard appearance with no engine modifications that may adversely affect reliability. Changes at the top of my list were:

Remove autolube oil pump – These pumps are a good idea in theory and have proved generally reliable over the years, BUT they increase complexity and there are many opportunities for parts of the system to fail. In most cases, one doesn’t discover that something is wrong until the engine seizes! With premixed oil and fuel, one knows that if the engine is running, it is receiving oil.

Replace vacuum-operated fuel tap by normal on-off-reserve type – While I can see some benefit with the vacuum fuel tap, that very small benefit comes with increased complexity. Also, I prefer to turn off the fuel tap at the end of a ride and let the engine run the float bowl dry (or at least as dry as possible). I consider that this reduces the chances of carb passages and jets becoming gummed-up on bikes that are not ridden very often, but it would be impossible to achieve with a vacuum fuel tap. Also, the diaphragms in vacuum fuel taps are known to fail occasionally, causing more trouble than the benefits they offer.

Replace battery with capacitor – Although I acknowledge that a battery is very handy in some circumstances, removing it generally reduces weight and frees up some space for storage. Batteries are also inconvenient to maintain on bikes that are not ridden often. Although modern battery chargers are available to optimise the condition of a battery while it is not in use, that is just extra expense and complexity I don’t need.
Most 2-stroke bikes of this era with a flywheel magneto system can run equally well without a battery, although I think it advisable to fit a capacitor to allow a “smoother” DC supply to the electronics.

Fit additional instruments – The instrumentation on a standard SDR is very basic, consisting mainly of a speedometer. For water temperature indication, there is only a warning LED which is lit at 105-115°C. There is another warning LED for 2-stroke oil tank level. There are also the usual “idiot” lamps (indicators, headlight high beam, neutral selection). Being a JDM bike, the SDR also has a speed warning lamp which is lit at 80km/h.
The minimum extra items I wanted were a proper water temperature gauge (either analogue or digital) and a DC voltmeter to warn of regulator failure. A tachometer was next on the list. I wouldn’t need either of the warning LEDs and the speed warning lamp would be of limited use.

Save weight where practicable – Other than removing the battery, an easy way to save a bit of weight is to fit an aftermarket exhaust system. The standard exhaust weighs a proverbial ton (actually 6kg), so replacing it with something lighter makes sense. Luckily the purchase price included an aftermarket SP Tadao Jackal pipe. According to my research, these offer similar characteristics to the standard exhaust system, but are much lighter (2.7kg). Pipes like the Jackal also incorporate a handy quick-release system by way of spring mounting to a stub manifold. EDIT: I fitted a DogFight Racing silencer to the Jackal pipe, just to be different and also because I had one spare from a pair I bought some time ago! I had to design an adaptor, as the Jackal and DFR silencers have their mounting holes displaced by 60 degrees.

I tackled a couple of other modifications with the bike still in one piece:

Changing of front brake disc and caliper – http://diffrentstrokers.com/phpBB2/viewtopic.php?t=1983
Fitting of cable-operated choke control – http://diffrentstrokers.com/phpBB2/viewtopic.php?t=2056

This is what the bike looks like now:





I will deal with various aspects of the rebuild in installments to follow.

Regards,
James


Last edited by James P on Fri Mar 24, 2017 12:00 pm; edited 1 time in total
Back to top
View user's profile Send private message
The Cameraman



Joined: 22 Aug 2015
Posts: 608
Location: Lancashire

PostPosted: Fri Mar 24, 2017 9:10 am    Post subject: Reply with quote

Hi James,

what a beautiful machine.

Well done that man.
_________________
Kindest regards


Reggie
Back to top
View user's profile Send private message
James P



Joined: 31 Mar 2013
Posts: 121
Location: Sydney, Australia

PostPosted: Fri Mar 24, 2017 9:34 am    Post subject: Reply with quote

In this installment, I will give a few details of the engine unit.

One thing I like to do when building an engine is to optimise the squish clearance. As standard, the SDR’s squish clearance was a little over 2mm. I wanted to reduce this to 1.0mm. The standard head gasket is about 1mm thick, so discarding it would be a good start. However, I would then need something to seal the combustion chamber and water jacket – why not use O-rings? Since I had never built an engine with the head sealed by O-rings before, I consulted the two-stroke specialist who builds my crankshafts and does my cylinder rebores. He said it should be no problem, as he had done many in the past – the most time-consuming part would be programming his CNC machine. He gave me a few pointers and I went back to consider the layout of the grooves for the O-rings. After making some measurements, I drew the design on tracing paper and laid it over the top of the cylinder – it seemed to fit perfectly. I calculated the sizes of O-rings I needed and went to my local supplier to see what was available. Armed with a few different sizes of O-ring, I took them, the cylinder and my design along to my two-stroke specialist for checking. I left the job with him and picked it up a week or two later. He had cut the grooves exactly as I had designed them, so I must have done something right.

This is the top gasket face of the cylinder after cutting grooves for the O-rings.



Test-assembling the top end on the engine casing with crankshaft and piston revealed the squish clearance was still slightly too large. As the piston crown was already level with the floor of the exhaust port at BDC, I didn’t want to lower the cylinder. With the O-ring grooves already cut, I didn’t want to skim the top gasket face either. The only remaining option was thus to skim the gasket face of the head – 0.6mm was satisfactorily removed by my regular machinist, mounting the head on a mandrel in the lathe.
Now that the squish clearance was set, I wanted to increase the volume of the combustion chamber to regain the standard compression ratio. Luckily the SDR head has a central spark plug, so it would be a relatively simple matter to mount the head in a mill using a mandrel in the plug hole. My regular machinist took care of this work, but I was on hand to measure the volume of the combustion chamber at intervals, to make sure that the correct amount of material was removed.

This is what the head looked like after combustion chamber modification:


The new volume of the combustion chamber gives a compression ratio slightly lower than standard, but I don’t necessarily see this as a disadvantage. Fuel is not what it was in 1987 and I didn’t intend to change the ignition timing, so a slightly lower compression ratio should aid reliability. Although I understand the concept, “corrected” compression ratios don’t make much sense to me. However, since Yamaha seems to use this method, I will offer the same relative information here. The quoted standard compression ratio is 5.9:1. My new compression ratio (as calculated using volume measurements obtained with the engine assembled) is 5.65:1 with the power valve fully open. For those interested, the old and new geometric compression ratios are 10.8:1 and 10.5:1 respectively.

A comparison of original and modified combustion chamber profiles:


While working on the top end, I discovered that there was some slop in the joint between the cylinder and head. There are only 5 studs and the stud holes in the head are a little too large to permit accurate location. It would be difficult to use dowels (as I would usually do on air-cooled engines), so some other method would be necessary. I eventually discovered that if the two outside studs were positioned concentrically in their corresponding holes in the head, the combustion chamber appeared concentric with the bore. I took the top end along to my machinist and he made two “test studs” which allowed me to confirm my initial tentative observations. He then made me two special steel bushes which were pressed into new counterbores in the head. The steel bushes have an inside diameter only marginally greater than the head studs, so allow almost no movement once the head is installed.

This is the arrangement of the steel bushes pressed into the two counterbored stud holes. Also shown are the test studs for confirming concentricity:


Luckily the cylinder bore was the standard size, albeit with a little wear. I had bought a new genuine piston (I was possibly one of the last to do so, as they were discontinued a short while later) and found that having the skirt coated with molybdenum disulphide (HPC DF1 http://www.hpcoatings.com.au/coatings-2/#Engine-Coatings) would be enough to take up the excess clearance, allowing only a light hone for bedding in the new rings.

The photos below shows the SDR piston (with skirt coating) and a DT200R (3ET) piston (without skirt coating). Now that SDR pistons are discontinued, it seems that the DTR piston is a suitable replacement (the compression height, dome profile and ring peg locations are the same as SDR). There are small differences in the cutaways, but I can’t see these making any noticeable difference in practice. The DTR pistons are still available in standard size and two oversizes. However, the DTR piston uses a shorter gudgeon pin (16x51, 4H7-11633-00) and a shorter small end bearing (16x21x19.5, 93310-316C9) which must be obtained to suit.





When test-assembling the top end parts, I found some lateral movement of the power valve drum. The clearance (about 1mm) seemed a little excessive, so I decided to try and reduce it. After considering all sorts of solutions, I decided that I should be able to “adjust” the two-part right-hand bush (31K-1131U-00) to reduce the clearance. Using suitable sockets in a vice, I managed to carefully push the two parts of the bush slightly further apart, ending up with a final clearance of about 0.25mm.


After cleaning the crankcase halves and putting them in the oven, the bearings dropped straight out. The needle rollers for the gearbox input shaft and clutch lever shaft were a little more stubborn, but came out with some slight persuasion. After thorough cleaning and relubricating, all the transmission bearings seemed good enough to reuse.
I wanted to replace the crankshaft main bearings as a matter of course. As the original bearings were designated 6305RCS-SH2 (later 6305RI), I thought it would be a good idea to “upgrade” to a 6305ETN9-C3, which uses a phenolic cage, saving weight and hopefully reducing the chance of cracking (as I had found in some of the standard rivetted steel cages). I also wanted to try an NJ305ECP-C3 roller bearing (same size as 6305 ball bearing) for the magneto side, as this would allow easier assembly and dismantling of the crankcase halves, without needing the special tool.

These are the relevant bearings:



When I finally got around to fitting the new bearings, I test-assembled the two crankcase halves with the crankshaft and ended up with a large gap (about 2mm) where the two faces wouldn’t meet – what could be wrong?? After dismantling again, I noticed that the new bearings seemed to protrude slightly more than I remember the original 6305RI doing, even though the new bearings were fully home in their housings. A quick measure revealed that the original bearings are not “real” 6305s at all – they are 1mm narrower!
I didn’t want to waste the new bearings and really wanted the ease-of-assembly advantage offered by the roller-type magneto-side bearing, so I investigated whether the housings in the crankcase could be modified to make the new bearings fit properly. After deciding that it should be worth proceeding with the modification, I had my machinist increase the depth of each bearing housing by 1.0mm. As the machining almost obliterated the oil flow grooves, these were also milled 1mm deeper and were later blended into the existing bearing lubrication holes by hand.

One of the bearing housings being machined:


After machining:




As the outer edge of the right-hand main bearing was now located 1mm further outwards, I also had my machinist grind the oil seal sleeve (90387-202T9) to reduce its length by the same amount.



After modifying the right-hand crankcase half, there was still sufficient allowance for fitting a standard oil seal. However, the left-hand crankcase half had been just right to start with and was now 1mm narrower. Some measurements revealed that I could still fit the standard 8mm wide left-hand oil seal, leaving 1mm protruding, without it fouling on the magneto stator plate. However, some research revealed the existence of a Suzuki left-hand crankshaft seal (09283-25066) which has the same internal and external diameters as the Yamaha seal, but 1mm narrower. I obtained one of these seals and found that it fitted just right!



The crankshaft was pressed apart and then rebuilt using the existing webs with new conrod, pin, bearing and shims. The 2TV conrod has been discontinued, being replaced by the 43G conrod. There are also other conrods which will work – one of my spare crankshafts had a 29L conrod fitted.
The crankshaft after rebuilding, with the inner track for the roller bearing fitted:



When I test-assembled the two crankcase halves with the crankshaft after completing the modifications, there was about 0.5mm lateral movement of the crankshaft in the main bearings. This would of course be prevented by tightening of the primary drive nut, but served to illustrate that no binding should occur in use.

One portion of the engine unit which caused me some worry was the clutch basket cush-drive assembly. I had a few of these among my various spare parts, but all exhibited some play due to slight deformation/compression of the rubber cushions. There is no mention in the SDR workshop manual of even checking this play, but there is such a check in the TZR250 1KT and 2MA manuals, specifying that the assembly be replaced if there is any play at all. Of course, the rubber cushions are not sold separately and I couldn’t find any suitable cush-drive rebuild kits. There was some slight wear (notching) in the clutch basket portion and I wondered whether I should replace the assembly with a new one (the 2TV assembly is discontinued, but the 3XP assembly replaces it). After discovering the price of a replacement assembly, I returned to researching solutions for reconditioning my existing parts. I briefly investigated a Hinson clutch basket for a YFS200, finding one fairly cheaply (at least less than the usual retail price) locally and buying it, but then being surprised that it didn’t come with new rubber cushions and also noticing that the high-tensile screws supplied for assembling it were American Standard thread (for an all-Metric bike!). I saw that Hinson offered new cushions for its RZ/YFZ clutch baskets (which are a slightly different size) and I enquired whether it could supply new cushions for its SDR/DTR/YFS basket. In typical (unhelpful) large-corporation-style, Hinson replied that it couldn’t supply the cushions I needed. Why would a company make a replacement clutch basket and not offer new cushions to suit?? If one’s existing clutch basket needs replacement due to wear, wouldn’t it be likely that the cushions also need replacement?? Thanks for nothing Hinson!
I did find a couple of references to replacement cushions for YFS clutch baskets on the internet and sent a few messages asking about them...I didn’t receive any reply. After my lack of progress in this department, I decided that I would attempt to use standard parts, reconditioned where possible. The wear in the clutch basket portion was easily taken care of by careful machining.

The clutch basket during machining:


The clutch plate thrust surfaces on the basket after machining:


This is the basket and centre boss after drilling a few lubrication holes. I'm not sure exactly how much difference this will make, but it couldn't hurt...could it?



I sorted through the rubber cushions from all my spare SDR and DTR clutch basket cush-drive assemblies, to make up the best set possible. I tapped the rivet holes in the clutch basket for Recoil inserts and used Metric (Hinson take note!) high-tensile button-head screws with high-strength Loctite to join it all back together. The rebuilt assembly does have some play, but it is less than before.

This is the clutch basket and cush-drive assembly before fitting the end plate:


This shows the amount of play in the cush-drive after re-assembly. I twisted the basket and gear in opposite directions as hard as I could to obtain this result:



From inspecting the standard SDR (blue) and DTR (pink) clutch springs, it seemed that the DTR springs were a little stiffer. I therefore ordered and fitted a set of new DTR springs. The ends of my clutch pushrods had indents from the coupling ball, so my machinist ground them flat for me. All other clutch parts (including plates) looked to be in good condition, so I reused them.

The gear shaft assemblies looked in good condition, but I dismantled them anyway to check for any galling or excessive wear. Everything proved to be OK, so I gave it all a good clean, then lubricated and reassembled.

The input shaft with gears etc.:


The output shaft with gears etc.:




The selector mechanism also looked fine, so it all got cleaned and reused as it stood, except for polishing the selector shaft. I had my machinist make me a protective sleeve for the gear selector shaft.



There is a mixture of finishes on the various castings of the SDR engine. The main crankcase halves appear to be bare aluminium. The left-hand and right-hand side covers (along with water pump housing and oil pump cover) are clear-coated, while the top end parts are all painted silver. There was some corrosion on the clear-coated parts and the silver paint on the top end parts had become patchy. I usually send my engine castings to Wayne Jacobson of Specialised Blasting Services (http://wetblasting.net/). His process consists of a very gentle wet bead-blasting, followed by ball-burnishing. The resulting finish is smooth and semi-lustrous. The burnishing process assists with retarding corrosion as it “seals” the surface – oil and grease just wipes straight off. Some of my engines received this treatment 10+ years ago and are still looking good. Only an occasional wipe is necessary to maintain the finish, but that only applies if used in dry weather and kept indoors. More regular maintenance is necessary if the metal is exposed to moisture for extended periods (e.g. if stored outdoors).
Castings after cleaning, before blasting and burnishing:


After blasting and burnishing:



Since Wayne’s wet bead-blasting process is extremely gentle, it takes ages to remove paint and similar finishes. I therefore treated all the clear-coated and painted parts to some paint stripper before sending them off for blasting. As well as the engine castings, I also had the same treatment applied to the fork sliders, top steering yoke, foot pegs & brackets, carburettor body, front brake caliper adaptor and rear brake master cylinder.

This is the two halves of the engine unit bottom end ready for joining:



I joined the engine halves together using zinc-plated high-tensile Allen screws, instead of the original Japanese Phillips screws. I used similar Allen screws on the left and right side covers as well.

My 8-point squish clearance check:


The engine mounts on SDRs seem to wear quite readily, so I wanted to make sure I renewed anything which looked even slightly worn. The front engine mounts seem to wear the most and/or quickest. Unfortunately, if wear is allowed to continue, damage is caused to the front engine mount adaptor bracket. I had 3 of these adaptor brackets and all were damaged from extended wear. The one on the bike was arguably the best, so I had it bead-blasted and then painted it black using POR-15 Rust Preventative Paint (I would have had it powder-coated, but didn’t want to risk damaging the rubber bushings). I bought the repair kit from SDR200.com, which contains enough parts for 20000km of use; 2 sets of steel bushes and 4 sets of bronze bushes with anti-friction coating. When fitting the parts, I found that the new bushes protruded beyond the end of the housing on the adaptor bracket on both sides, due to the wear which had previously occurred. So that damage would not be done to the bushes when tightening the mounting bolt, I had my machinist make some special steel caps with recesses, so that the bolt would be tightening onto the bracket housing, not onto the bushes.







I had also had some special 8mm shims made, so that the adaptor bracket (with new bushes fitted) would be a snug fit onto the engine casing, with no play.

The rear engine mounts were not quite so worn as the front ones, but had seen better days. The rear engine mounts are no longer available from Yamaha, but luckily SDR200.com supplies a suitable kit. The kit employs a different type of mount, but includes a custom-made spacer sleeve which takes care of the differences. The kit also contains a different version of the special rubber-coated washer which is fitted on the right-hand side (also no longer available from Yamaha), although I wanted something a little more robust. I designed some special washers/spacers to be fitted to both sides, which I considered should prevent (or at least drastically reduce) movement in the horizontal plane, but allow slight movement in the vertical plane.






I am also in the process of fabricating a kit for the third engine mounting (not fitted as standard), along similar lines to the one sold by Tosh-Tec in Japan (the Tosh-Tec kit uses a mixture of custom-made and generic parts and is very expensive!).
This is the Tosh-Tec kit:


This is my kit (so far):



Further details to follow!


Regards,
James


Last edited by James P on Mon Nov 06, 2017 5:44 am; edited 1 time in total
Back to top
View user's profile Send private message
James P



Joined: 31 Mar 2013
Posts: 121
Location: Sydney, Australia

PostPosted: Fri Mar 24, 2017 9:35 am    Post subject: Reply with quote

The Cameraman wrote:
Hi James,

what a beautiful machine.

Well done that man.


Thanks very much Reggie - more details in the pipeline!

Regards,
James
Back to top
View user's profile Send private message
James P



Joined: 31 Mar 2013
Posts: 121
Location: Sydney, Australia

PostPosted: Fri Mar 24, 2017 10:06 am    Post subject: Reply with quote

This portion deals with the intake and fuel supply systems.

I initially planned to keep the intake system all standard, but had a rethink when I discovered the complexity of the SDR’s air filter assembly. Air filter elements are still available new from Yamaha, but many of the other filter-related parts are discontinued. After inspecting the layout of the air box, I decided to make an adaptor to fit a K&N pod filter inside the box. This would do away with all the standard air filter parts and arguably provide better air flow with at least equal filtering quality. As the increased air flow would likely require different carburettor jetting, I decided on a custom-built carb to suit.
I already had a single TM28SS carb from a TZR250 2XT model sitting on the shelf, which I had bought in the 1990s for investigation and never used. This carb is nearly identical to the standard SDR carb, but has screwed-in main air jet and power jet in place of the pressed-in jets of the SDR carb (the TZR carb also hasn’t got the arguably pointless heating system connections, which I wasn’t going to use anyway).
My experience has told me that using air jets causes a lot more faffing about when trying to set up a carb, so I decided to convert the carb to TZR Formula 3 specification. This involves replacing the 505-series bleed-type atomiser by a 159-series primary-type atomiser (which are much easier to get and are available in a large range of sizes) and using a different needle (5EJ48 instead of 5L19). I went one step further to get rid of the pilot air jet as well, by using the front bellmouth casting from a TZR250R/RS (3XV) carb – this has a pilot air screw instead of a pilot air jet, which allows more user-friendliness when setting up the pilot circuit.



I don’t have much experience with setting up power jets (i.e. deciding the relative sizes of main jet and power jet), so I have so far just blocked the power jet passages and increased the size of the main jet accordingly.
One thing I found interesting was the difference between the TZR throttle slide and the SDR throttle slide. The two types are physically interchangeable, have the same cutaway and appear practically identical on the outside. Almost by accident, I discovered that the counterbore for the needle clip in the SDR slide is 1.5mm deeper than that in the TZR slide. Therefore, a needle on the same clip position in each slide will be one-and-a-half positions leaner when used in the SDR slide. However, the SDR slide effectively offers a greater range of adjustment by using the two 0.8mm plastic spacers which come with OEM Yamaha needle kits. In fact, it is necessary to use both of these spacers with the SDR slide to make sure there is no vertical play in the needle when installed. In the standard arrangement, both spacers sit on top of the needle clip, but may be moved beneath the clip (or one above and one below) to obtain different characteristics (offering a much larger range of needle adjustment than the 5 clip grooves). Despite offering such a large range of adjustment, it is often unnecessary – the 5 clip positions usually offer ample adjustment in practice. However, the SDR slide may come in handy in certain circumstances.

As I wouldn’t be using the autolube oil pump, I could do away with the SDR’s bulky standard multi-way throttle cable. All I needed was a single cable from the twist-grip to the carb, so I made one myself using bits I bought from Venhill.

After making some measurements, I designed a two-part adaptor to fit the K&N filter (RU-0210) to the SDR air box. My machinist made the parts for me on the lathe and then pressed them together to form the stub adaptor. In my initial design (which I am using), the stub adaptor is retained by a separate ring, secured by three M4 screws. It was necessary to drill corresponding holes in the air box to accommodate these screws, although they are not very obtrusive.







I have subsequently thought of a similar design which requires no holes in the air box, but have stuck with my initial effort because the modified air box would otherwise be wasted, especially since I have painted it! I initially thought I could get away with just lightly polishing the existing silver paint on the sides of the air box, but some of the stains proved impossible to shift without affecting the surrounding paint. Therefore, I cleaned up the rough-cast portions of the box in my small blasting cabinet and sprayed them with clear coat. I flatted back the painted sides with wet & dry paper and resprayed them with a silver colour similar to the original. All went well and I applied new “SDR” decals which I’d bought from Japan. I found it difficult to decide whether to apply clear coat over the decals and silver base (it is difficult to tell whether this was done as standard), but eventually decided to apply the clear coat. Again, all went well and I left the air box in the attic for the coating to harden. I checked it after a few days and all still seemed good, but I left it where it was as I wasn’t ready for it at that stage. I checked it again a couple of weeks later only to find that the clear coat had cracked – Doh! I thus removed the nice new “SDR” decals, destroying them in the process (grr!). I again flatted back the sides of the air box and reapplied the silver paint. This time, I decided not to apply clear coat! More decals were ordered, received and successfully applied. The finished product still seems OK so far.



The only other part of the standard air intake assembly I decided to retain was the plastic air box top, mainly because it serves as a mounting point for the piece of foam, which itself acts as a wiring loom retainer and fuel tank cushion. I reasoned that air flow could be optimised by cutting a larger hole in the air box top, but I didn’t want to destroy a good top. Luckily I did have a spare top which had already been hacked about. Sadly, its piece of foam had also been hacked about, so I would have to make a new one (this part had long been discontinued by Yamaha). After some searching, I found a local place which sold foam of the approximate thickness and density I needed. With a bit of experimenting, I managed to fashion a new foam piece and glued it in position with Araldite.
On the left in this photo is a standard air box top in good condition. On the right is the one I decided to use (prior to modification!):


After modification (but before fitting my remade foam piece):


The good standard part on the left and my modified part on the right (with remade foam piece). In front is the foam piece previously fitted:



As one of my aims was to get rid of the standard vacuum-controlled fuel tap, I drew upon previous experience with my KR-1 and TZR250 in carrying out such conversions. The SDR fuel feed system is very similar to that on the TZR. Most Yamaha and Kawasaki fuel taps (not sure about Suzuki and Honda) are made by Taiyo Giken. Many different styles are supplied and it is usually possible to find something that will do the job with minimum trouble. I think the tap I ended up using for the SDR is from a ZXR750, although there are several different versions of the same thing. For instance, the same tap casting is used on a KLX250, but inlet and outlet holes are drilled in different positions and/or have different sized fittings pressed in. Handily, most of them use the same size sealing washers and O-rings, which can be bought fairly cheaply as OEM parts, instead of shelling out more money for aftermarket tap rebuild kits containing parts one may not need.
I made an adaptor from aluminium plate to couple the new fuel tap to the existing mounting point on the SDR. The fuel tap in the photo is not the exact one I ended up using, but has the same body casting.



Two hoses for normal and reserve fuel supply lead to the fuel tap assembly. The outlet from the fuel tap leads to the carb, via a quick-connect fitting and an in-line filter. I also have the standard “sock” filter in the carb fuel inlet passage.
The interior of the fuel tank was rusty, but not seriously so. I have used the POR-15 treatment on more than a dozen fuel tanks over the last 20 years or so and found that it works well if the instructions are followed. Although the SDR tank was not too rusty, there was a lot of other gunk inside, which required multiple cleaning and flushing before preparing for sealing. I have found the SDR tank to be one of the most difficult I have so far encountered, as there are many narrow sections which are difficult to examine. Also, it is difficult to empty the tank completely – I found the easiest way was to hold the tank upside-down and use a rag to soak up the last of the liquid, then withdraw it through the filler hole.

The fuel filler cap assembly looked OK at first glance, but I thought I should probably dismantle it for cleaning and checking. The assembly has a lot of parts and I had to take a few photos during dismantling to make sure it all went back together correctly. Dismantling everything gave me the opportunity to service the lock barrel – although it still worked, a few of the sliding “wafers” were gummed up and took some effort to free without damaging them. The aspect with which I had the most trouble was removing the hinge to separate the cap and the surround. I initially thought a single long roll pin was used as the hinge, but after lots of gentle tapping and no movement, I surmised that two separate roll pins had been inserted into blind holes, one on each side. After a lot of faffing about, I eventually extracted both roll pins. To do this, I drilled the centre of each pin and tapped it to M3. An M3 screw was then inserted, providing a much easier means of removing the pin(s) by several alternative methods. Unfortunately, I caused slight damage to one of the pin holes during drilling, such that a new pin may not hold. Luckily, my welder/machinist was able to drill the hole all the way through the cap, enabling me to use a single length of 3mm stainless steel rod as the new hinge.
Drilling the pivot hole all the way through in the mill:


More info in the next installment...

Regards,
James
Back to top
View user's profile Send private message
James P



Joined: 31 Mar 2013
Posts: 121
Location: Sydney, Australia

PostPosted: Fri Mar 24, 2017 11:09 am    Post subject: Reply with quote

Here are a few details on the instrumentation and electrics:

With the extra instruments I wanted to fit, I decided to try and make the new set-up appear as “factory” as possible.
The first task was to obtain a set of instruments from an SRX250 (3WP model). This version of the SRX used an instrument set-up nearly identical to the SDR, but the speedo bracket had a tachometer mount attached and there was no speed warning lamp provided. The SRX speedo itself is the same as SDR, except that it has no warning LEDs. These features made it nearly perfect for my needs. The speedo rim on the SRX unit is chrome instead of black on the SDR, but I wasn’t too bothered about that.
The 2TV and 3WP instrument clusters:



I initially planned to just use the SRX tacho mount to fix an aftermarket electronic tacho, but some observations I made caused me to investigate using the standard SRX mechanical tacho instead.
There are several other Yamahas which have crankcases similar to the SDR, such as TZR125, DT125R and DT200R. Many versions of these bikes employ a mechanical tacho driven from the primary drive gear on the clutch basket. I was surprised to find that SDR crankcases already have the necessary casting and machining done to fit the ring and pinion tacho drive gears from other models so equipped from the factory. The only problem I encountered was that I could not obtain tacho drive gears of the exact ratio so as to produce a thoroughly accurate indication. The closest I found was a set of tacho gears from a DT200R. The DTR has 17-52 primary drive gears in comparison to the SDR’s 18-51. I calculated that the tacho drive ring gear would be rotating 6% faster on the SDR than for the same engine speed on the DTR. Thus, at 10,000rpm on the SDR, the tacho will indicate 10,600rpm. As the higher indication amounts to something of a safety feature (i.e. real engine speed is lower than indicated), I decided I could put up with that. Some rough calibration checks on the SRX tacho revealed it possesses a ratio of about 5:1 (i.e. it indicates 5 times the actual speed of the tacho cable). At 10,000rpm, the DTR tacho drive pinion gear rotates at 2000rpm (2120rpm on the SDR), so the SRX tacho is ideally suited. I checked the fit and mesh of the DTR tacho drive ring gear with the SDR clutch primary gear and it looked OK. There was clearance when the gears meshed, so I do not anticipate any problems in this regard.
I subsequently found an internet reference to a certain Hiroshi Iwasaki, who had apparently made a small batch of special tacho drive gear sets just for the SDR in Japan. However, the information was almost 10 years old and it stated that all sets had already been sold. Although there was suggestion of another batch being made, I was unable to find any updates.

The DTR tacho drive gears fitted to the SDR engine casing:



For the tacho cable, I ended up buying 3; aftermarket and genuine DT125/200R and genuine TZR125. In practice all of them fit and work, but I found the genuine DTR cable to be the best fit.


As I would be using a “proper” water temperature gauge (instead of just the standard thermoswitch and warning LED), I wanted to make sure I obtained suitable equipment, preferably genuine Yamaha. After some investigation, I decided to use a TDR250 temperature gauge and thermosensor. I fabricated a case for the TDR gauge from aluminium tube and plate (which my welder/machinist welded together for me), then made a mounting bracket from a piece of scrap steel.
The rear of the instrument cluster, showing the bracket for the TDR water temperature gauge:



As there are no graduations on the TDR gauge, I decided to roughly calibrate it. This involved setting up the TDR gauge with its thermosensor in a pot of water on the stove. Using a TZ/RS racing temperature gauge (which works on the Bourdon tube principle) as a reference, I took photos of both gauges side-by-side at 5°C intervals as indicated on the TZ/RS gauge.
TDR vs TZ/RS gauge at 70°C:


...and at about 98°C (the maximum I could achieve):



Some may ask why I didn’t just use the TZ/RS gauge on the SDR in the first place. The reason is that the thermosensor portion is far too large for the boss on the SDR cylinder head (the thermosensor is designed to fit a boss on the radiator on TZ and RS racers). I could have modified the SDR’s thermostat housing to provide a mounting for the thermosensor of the TZ/RS gauge, but it would have been too prominent and the tube would likely have been in the way of something. Of course, since the TZ/RS gauge works on the Bourdon tube principle, the gauge head, tube and thermosensor portions are permanently connected together and cannot be separated.

I like to monitor the temperature of the cylinder head and exhaust gas on any bike I use, so a CHT & EGT gauge would be essential for the SDR. Any abnormal rise in these temperatures can indicate air leaks or other developing conditions which may quickly lead to holed pistons and/or seizure. If noticed early, the engine can be stopped or made to run slower/lighter to reduce or even eliminate the likelihood of damage.
Most of my other bikes have Westach 2DC1-2 instruments fitted (one for each cylinder), which provide dual indication of CHT and EGT. For convenience, I would probably prefer a digital indicator, but the Westach instruments have proved reliable, robust and reasonably cost effective over the years and I have therefore made them my “standard”.
I would normally have my welder/machinist make a threaded boss for the EGT thermocouple and then weld it onto the exhaust header pipe, so that the thermocouple is positioned less than 100mm from the piston skirt. However, the stub manifold for the Jackal exhaust on the SDR is quite thick and (as it turned out) quite suitable for drilling and tapping to mount the EGT thermocouple. A spot face was also created to allow the thermocouple to sit perpendicular to the exhaust passage. With this arrangement, the thermocouple tip is located about 65mm from the piston skirt.





One problem I encountered was that the standard Westach EGT thermocouple fouled the radiator. Shortening the thermocouple would have been difficult without damaging the wires and would likely have left a sharp edge on which the wires may later abrade. After considering all sorts of undesirable modifications to the radiator brackets to obtain clearance, I simply asked Westach to make me a shorter thermocouple! Luckily this was no problem and the special thermocouple fits well. It is still very close to the radiator, but doesn’t touch.





The CHT thermocouple is just a standard item with a 14mm ring end, which fits under the spark plug.
I fabricated a 2-part bracket for the CHT & EGT gauge which fits underneath the M8 flange bolts securing the top of the engine cradle to the frame. I also made a case for the gauge similar to the one for the TDR water temperature gauge.



A voltmeter is something else potentially useful on bikes whose electronics (and battery charging) rely on the +12V DC supply derived from the magneto. If the regulator portion of the rectifier-regulator fails, severe damage is soon done to CDI units and other electronic components as the magneto output voltage rises to something like 40-60V. If the voltage can be continuously monitored, it is at least possible to stop the engine before damage occurs. I have already described voltmeter installations on my KR-1 and TZR250, as detailed here:
http://www.kr-1s.co.uk/forum/viewtopic.php?f=13&t=12509&p=89057&hilit=regulator+early+warning#p89057
http://pure2strokespirit.net/forums/index.php?topic=3212.msg35515#msg35515

This is the layout of instruments, as completed:



I had a few standard HT coils and all their HT winding resistances measured within specification, but the insulation on all of their HT leads had grown hard over the years. This may not necessarily be a problem in use, but I wanted to see whether I could successfully replace the HT lead on at least one coil. I was extremely lucky with the first coil – the HT lead just screwed right out. Unfortunately, the other two were not quite so accommodating – I damaged the HT leads to the extent that the coils would have been scrap if the leads could not be replaced. I thus had nothing to lose by going further to see if I could completely remove the damaged HT leads. On the second one, I cut open the passage into which the HT lead passes and eventually managed to dig out the remains of the old HT lead, leaving the spike which connects the HT lead to the coil winding.



To repair this coil, I fitted a length of new HT lead and Araldited it into position, then Araldited back in the piece which I had cut out.

On the third coil, I reasoned that carefully drilling a hole near the base of the HT lead would be enough to remove the remains and then allow a more robust repair.



I fitted a length of new HT lead to the third coil and again secured it with Araldite. I then filled the hole with Araldite to complete the repair.

After the Araldite had set, both repairs seemed OK.



Just in case repairing the standard HT coils didn’t work, I had a Plan B. This involved using a slightly different type of HT coil, in this case a Ducati Elettrotecnica coil (from a Gilera Runner I think), a couple of which I found among my spare parts (one genuine, one pattern – both of which possessed resistances in the range required for the SDR). Of course, this type of coil was not a straight replacement. Its body is slightly larger and it is of “shell” type construction (where the laminated core forms a loop back onto itself). However, after a few measurements, it didn’t prove too difficult to make an adaptor bracket.
The genuine (black) and pattern (red) Ducati Elettrotecnica HT coils with the adaptor bracket I made:


The relative orientations of the standard SDR HT coil and my Ducati Elettrotecnica replacement with adaptor bracket:



The input terminal is located on the opposite side when compared to the standard SDR coil, but luckily the wire from the SDR loom has sufficient free length to reach the terminal without stretching. This is one of the alternative replacement HT coils fitted:



Should all of my repaired standard HT coils fail, I at least have a back-up plan! Handily, the Ducati coils feature removeable HT leads – just unscrew and replace.

The rest of the electrical system is largely standard, although I made up a sub-loom to connect the additional instruments and also to adapt the 6-pin SRX instrument panel connector to the 9-pin connector in the SDR loom, which avoided the necessity of having to cut any wires. Luckily the sub-loom fitted behind the headlight with everything else, but only just.

The capacitor box I made up is identical to the one I fitted to my KR-1; 3x 10000uF 40V electrolytic capacitors in parallel, inside a box. The capacitors and box were bought from local electronic components retailer Jaycar.



More details to follow.


Regards,
James
Back to top
View user's profile Send private message
James P



Joined: 31 Mar 2013
Posts: 121
Location: Sydney, Australia

PostPosted: Fri Mar 24, 2017 11:53 am    Post subject: Reply with quote

When I had the bike dismantled to the bare frame, I couldn’t decide what to do about the finish on the frame and swing arm. There were some patches of surface rust in areas that are not easily seen, but the standard chrome plating was otherwise in very good condition. Unfortunately, the original clear-coat was not quite so good – in some areas it was as new (so resilient that even paint stripper hardly affected it), but in others it had turned so brittle that I could scrape it off with a fingernail. I decided that rechroming would take too long and cost too much – I wasn’t trying to restore the bike to showroom condition. Even just stripping off the clear-coat would be a lot of work. I ended up just cleaning off the surface rust and treating those areas with rust converter. Although the patchy clear-coat was a little unsightly in some places, it was only obvious close-up. There are some small areas on the SDR frame and swing arm which are painted silver from the factory, so I cleaned these areas up and applied a couple of coats of silver POR-15 Rust Preventative Paint – job done!

The black paint on the engine cradle and seat sub-frame had turned a little shabby over the years. I could probably have just cleaned these parts and touched them up, but their shabbiness would have stood out against the nice clean finish on the engine. Thus, I had them both bead-blasted and powder-coated satin black by a local firm.
I had been lucky enough to buy a set of bodywork (fuel tank, front mudguard and seat cowl) in original red paint from the same bike via Yahoo Auctions. Although all parts have small blemishes and the paint is faded in some places, they are all in pretty good original condition. Therefore, no refinishing was necessary, except to clean out and seal the interior of the fuel tank.
The original paint on the wheels was also pretty good, so all I did was give them a clean and have new tyres fitted. The wheel bearings seemed OK, so I left them alone, only fitting new seals. The paint on the speedo drive gearbox was very shabby indeed, so I dismantled the unit as far as possible. The ring gear came out easily enough, but although I successfully removed the roll pin, I couldn’t extract the brass fitting and pinion gear.



I therefore just cleaned out the casing, thoroughly masked it up and blasted off the original paint, then sprayed it silver to closely match the paint on the wheels.


The fork assembly looked in pretty good condition – the stanchions were straight and there were no oil leaks. Unfortunately, the clear-coat on the sliders had yellowed slightly with age and/or exposure and corrosion was beginning to take hold in a few places. After dismantling, I sent off the fork sliders with the engine castings to be wet bead-blasted and burnished. A good measure of paint stripper and elbow grease was required to remove the clear-coat beforehand though.

I wanted some fork spring preload adjusters, but there wasn’t much available for the SDR. The only off-the-shelf adjusters for the SDR I could find were the OX Racing ones at ¥14000. However, a bit of research suggested that adjusters for other models may fit with small modifications. I ended up buying some Posh-Faith adjusters (SR400/500, TW200) for ¥9800. The only modification required was to turn down the outer edge of each cap in a lathe, as they had been made to suit 35mm forks instead of 33mm (the thread is the same though).



Sometime later, there was a flood of cheap Chinese adjusters which could be bought on Ebay for about $30 per pair...!

The workshop manual simply specifies “Yamaha Suspension Fluid” for the forks, so I had no idea what viscosity it should be – I just used some new No.10 fork oil, the same as I had already used for my KR-1 and TZR250. All parts to rebuild the forks (anti-friction bushes, oil seals, dust seals, clips etc.) are still available - the SDR fork assembly is identical to all SRX250 models (the springs are the only difference).

Luckily the rear shock absorber was in good condition – no leaks and it still had nitrogen pressure. All I did was remove the spring for bead-blasting and powder-coating before cleaning up the damper body and reassembling.
I have all the suspension settings as standard for the time being and will see how it goes on the road. The SDR’s rear shock absorber has the same dimensions as the 1988-and-onwards TZR250 (i.e. 2XT, 2XU, 2XV, 2XW etc.), so a heavier-duty unit should be obtainable if the standard one proves unfit for whatever reason.

I fitted a set of tapered roller steering bearings to replace the standard loose ball set-up, although this was done mainly for convenience during any future dismantling. The lower steering yoke was bead-blasted and powder-coated, while the upper yoke was stripped of its clear-coat before being sent for wet bead-blasting and burnishing. The standard clip-on handlebars were in good condition, so they needed only cleaning. Although I have a set of standard handlebar ends, I researched a set of alternative ends. The standard ends are aluminium and very light (also no longer available from Yamaha and expensive to custom-make). The fitting of heavier ends as a means of damping vibrations seems popular, so I found a suitable set from an FZR250. The only modification required was to machine down a portion of the shoulder to match that on an SDR handlebar end.
This photo shows a standard SDR handlebar end on the left, with a modified FZR handlebar end on the right:



The original SDR handlebar ends weigh 53g each. The steel FZR ends weigh 204g each, although some of this will be lost in machining. The FZR ends are still available from Yamaha in black (1GU-26246-00) or silver (3HX-26246-00) and were used on quite a few different bikes (including silver ones on the OW-01). SRX250 handlebar ends (51Y-26246-00) are also made from steel and should work, but I haven’t got a set to check. No doubt there are other handlebar ends which could also be fitted, but the slightly oddball M16 thread means that most generic aftermarket items won’t fit.

One part which is no longer available for the SDR is the special chain buffer (2TV-22153-00) which fits around the horizontal frame brace above the rear engine mount.
These are the two buffers I have; bad on the left and worse on the right!



I have never seen these buffers offered for sale NOS or used – even Tanaka-san at SDR200.com couldn’t supply one.
They sometimes get left on frames when bikes are dismantled for parts. Although frames can sometimes be obtained cheaply, the chances of the buffer being in good condition would be remote – although they rarely make contact with the chain, they seem to harden and crack over time.
Both buffers I had were unusable – one had already cracked in half and the other was just about to do the same. I briefly investigated having a replacement specially made, but decided it would be too complex and costly. Instead I set about making up something which would do the same job, from stuff I already had lying around:



The new buffer consists mainly of 3mm thick rubber strip with clamp plates made from 5mm thick aluminium plate. There is also a tube spacer to prevent the rubber being clamped too tightly and all parts are secured with a stainless steel M6 screw, 2 washers and a nylock nut.
This is my new buffer assembly installed:



I wanted to try modifying the rear mudguard because I think the standard one spoils the look slightly. I didn’t want to destroy a good mudguard, so bought one cheaply via Yahoo Auctions which had already been cut. When I later removed the standard mudguard from the bike, I discovered it had a large crack, meaning that I really need not have bought another one to modify - oh well...
After experimenting with varying cutaways, I eventually settled on removing the protruding section of the mudguard entirely, leaving only the “tray” section. I fabricated a new number plate holder and two support brackets which incorporated mountings for the indicators:



After confirming fit, I had the number plate holder and brackets bead-blasted and powder-coated satin black.

The headlight mountings caused me some trouble. As standard, the headlight shell pivots on plastic bushes which are held by 2-part grey rubber plugs. I had several sets of these rubber plugs and all were in a state of decay. They seem to have assumed the consistency of cheese, some of them having already cracked and/or disintegrated. The larger part is still available from Yamaha (relatively expensive), but the smaller part (an oval rubber washer with a square hole in the centre) has been discontinued. Other Yamahas use similar parts, some of which are still available but also relatively expensive and not quite correct. After a bit of research, I found that Suzuki GS400 indicator mounting bushes could be used instead. These seem a bit more robust and are more cost effective than mixing and matching new Yamaha parts. A picture is worth a thousand words, so I have made one up showing the two systems:



I had a few headlight brackets in varying conditions. All were structurally sound, but the chrome plated finishes had suffered to varying degrees over the years. I selected one bracket for rechroming and took it to a chrome plater I sometimes use. There are a few intricate spots in the headlight bracket which are difficult to polish properly – some of these had very slight rust pitting. I went to some length to explain that I didn’t want a super-shiny finish and suggested that polishing be kept to a minimum, so as not to produce sharp contrast between the highly-polished areas and the hardly-polished areas. I was informed in no uncertain terms that the finish would be “better than new” and I should leave it to them – the experts. When I collected the bracket, I was of course dismayed to find that the easily-accessible areas had been over-polished (rounded-off edges) and the less-accessible areas had received next-to-no polishing. The end result looked a real mess and I resorted to using the best of the original-finish headlight brackets instead. I have used that particular chrome plater in the past for less-intricate jobs and found their work above average. However, I shall strike them off my list for items like this in future. I should have just had the bracket bead-blasted and powder-coated silver.

I tried to reuse as many of the original chassis fasteners as possible, which meant cleaning up and replating with zinc. My zinc plater doesn’t do the dark olive colour which some of the SDR parts appeared in, only silver and gold. However, I think that all of those parts turned out OK in silver and don’t look particularly out-of-place as a result.

Unfortunately, the front and rear sprockets on the SDR are uncommon, only being used on a few different bikes. The sprockets on the bike didn’t look too bad, but the chain had suffered from neglect. I decided to replace the lot and came across XAM Japan, maker/supplier of a range of sprockets and supplier of all sorts of other parts for motorcycle and go-kart racing. Man-in-charge Jun Oshiro was very helpful and supplied a pair of his own brand sprockets and an RK X-ring chain for a very reasonable price (less than I would have paid if buying the parts separately elsewhere). At 188g, the anodised aluminium XAM rear sprocket is much lighter than the 485g standard steel item, which can only be an advantage.

Although I have covered the replacement front brake disc and caliper elsewhere (http://diffrentstrokers.com/phpBB2/viewtopic.php?t=1983), I will give a few more details of the rest of the braking system. The front brake master cylinder comes from a Suzuki RG200 (the same as late RG125) and has a half-inch bore. I am aware of the need to match master cylinders to calipers to provide the correct ratio, but have only a little experience with non-standard set-ups. There are many more factors (disc diameter, wheel diameter, brake pad material, lever pivot distance etc.) which go towards providing the correct “feel” and performance of a braking system, but the piston area ratio of this master cylinder and caliper combination seems to be within the acceptable range, according to information I found on the internet! The front brake seems OK so far, but I’ll see how it performs once bedded in.
I dismantled the calipers, cleaned and blasted them, then painted them silver. The rear master cylinder was dismantled, cleaned, paint stripped (that which was still left on after signs of previous leaking) and then sent for wet bead-blasting and burnishing. The black paint on the front master cylinder was in excellent condition, so the unit was dismantled, cleaned and reassembled. I have fitted some braided brake hoses from Venhill.

At the time of writing, the bike has covered only 20km. I rode it for 15km around my storage unit complex to get the carb jetting in the right ballpark and to check for any obvious defects, leaks etc. The other 5km was the round trip for the roadworthy inspection. I'll post some more details if anything transpires. If anyone has any questions about any other aspect of the bike, please let me know.

Regards,
James
Back to top
View user's profile Send private message
James P



Joined: 31 Mar 2013
Posts: 121
Location: Sydney, Australia

PostPosted: Fri Mar 24, 2017 12:05 pm    Post subject: Reply with quote

Here are a couple of photos I forgot to include in previous posts, showing the bike part-way through reassembly:





Regards,
James
Back to top
View user's profile Send private message
Top-shaggy
Show Star !
Show Star !


Joined: 05 Mar 2011
Posts: 1678
Location: Derbyshire

PostPosted: Fri Mar 24, 2017 2:51 pm    Post subject: Reply with quote

Wow James...
What a great thread. Thanks for posting Smile
I wish you would get an AR and do that too..lol
Brilliant read !
_________________
We are where we are...
Back to top
View user's profile Send private message
andyw114
Show Star !
Show Star !


Joined: 01 Jan 2014
Posts: 274
Location: Near Kidderminster

PostPosted: Fri Mar 24, 2017 8:06 pm    Post subject: Reply with quote

Great work. Brilliant engineering.
Back to top
View user's profile Send private message
yamfan



Joined: 11 Jul 2016
Posts: 119
Location: Ireland - South east

PostPosted: Mon Mar 27, 2017 9:00 pm    Post subject: Reply with quote

Wow, that was fairly involved

You don't do things by half!

I really like the SDR's in red Cool
Back to top
View user's profile Send private message
The Cameraman



Joined: 22 Aug 2015
Posts: 608
Location: Lancashire

PostPosted: Mon Mar 27, 2017 9:58 pm    Post subject: Reply with quote

Fabulous work Good Sir, fabulous!
_________________
Kindest regards


Reggie
Back to top
View user's profile Send private message
James P



Joined: 31 Mar 2013
Posts: 121
Location: Sydney, Australia

PostPosted: Thu Mar 30, 2017 12:27 am    Post subject: Reply with quote

Thanks everyone - I'll post some more details if any developments occur!

Regards,
James
Back to top
View user's profile Send private message
James P



Joined: 31 Mar 2013
Posts: 121
Location: Sydney, Australia

PostPosted: Thu Apr 06, 2017 11:33 am    Post subject: Reply with quote

I rode the SDR today to continue the running-in process.

Upon starting out, after closing the choke the bike would stall. There was no problem once the throttle was opened, so it seemed as if there was a blockage in the pilot circuit. Luckily my handlebar choke control can be set to open the choke only slightly, which was enough to let the engine idle.
I went to fill up with petrol and decided I would investigate the problem when I reached a quieter area.
After riding about 5km, I decided to find a spot to dismantle the carb to see if I could get the pilot circuit working again. I pulled over and closed the choke completely, but the engine carried on idling as if nothing had happened! I just rode off again... Confused

I rode for 100km and didn't experience any more carb trouble. There was a slightly lean spot around one-eighth throttle, but otherwise the jetting seemed OK. As development continues, I will still change the various jets to prove the set-up though.

Here are a few photos I took along the way:

At Long Bay/Malabar Beach:



On Prince of Wales Drive, Port Botany:




In the last photo, it is obvious how narrow the SDR is!

I'll post anything further of interest as it happens.

Regards,
James
Back to top
View user's profile Send private message
Howie



Joined: 18 Oct 2009
Posts: 471
Location: Kwaksville

PostPosted: Thu Apr 06, 2017 2:19 pm    Post subject: Reply with quote

WOW!

Stunning bike, stunning scenery.

Cool
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    Diff'rent Strokers Forum Index -> Yamaha All times are GMT
Goto page 1, 2, 3  Next
Page 1 of 3

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group.  Installed, administered and modified by  Diff'rent Strokers © 2006-2018.