Diff'rent Strokers

[eire_kp61]

well all, been meaning to sign up here for ages

after owning almost 20 2stroke yokes over the years i think il enjoy this site.

heres a few pics of my 3xv

I picked it up in london at the start of the summer and drove it painfully home to kilkenny in ireland.

with only 9000km on it the bike behaved perfect , the previous owner said he had the 2t pump turned up but that was an underestimate.

it billowed blue smoke the whole way home and drank 5 bottles of oil

heres the pics anyway







thats before i fitted the nikkons i got from karl on the site here.

I plan on taking it off the road shorly for a full restoration, the fairings are a bit tatty so il be looking for mint original ones and as many new bits as i can get , yahoo japan is a great spot

Today the engine started vibrating , you can feel it through the frame,
the big end is hardly giving bother at such low mileage ?

is there any thing that gives bother in the 3xv that is causing this ?
little end bearing would hardly cause a vibration ?

its still running fine but it might be engine out time for a full rebuild

I have my ''45hp'' ecu coming soon but im gona have to wate to fit it now

[arlurt]

Hi Chris, and welcome to DS.

I think you've read my 3XV post haven't you? The only sign that a big end bearing was on the way out was vibration that I'd thought was wheel balance... My bike had just 12,000 Km on the clock when it let go completely.

I think mine failed early because it had suffered a ring failure at some time before it left Japan. It was misfiring when I got it, a top end strip revealed that part of a top ring was missing, with bits of ring stuck in the piston crown and in the head. This must have over stressed the big end bearing, so that when I fitted a new piston and changed the CDI it couldn't hang on much longer. The big end broke up completely, needles loose in the cases, and seized the crank in the cases.

If you're prepared to pull heads and barrels off you should be able to check the wear in the big ends without removing the engine from the frame. The workshop manual tells you how much sideways movement is allowed at the little end of the con-rod, and that’ll give you an indication of big end wear.

By your two-stroke history you may already know all this, but it might be useful for anyone else on here with a 3XV with an unexplained vibration.
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[eire_kp61]

i have read your thread but i forgot the details, i didnt realise yours was on such low mileage when it gave up

Ive rebuilt many an engine so have no problem doing the work myself

my 3xv came with reciepts from a bike shop saying it had had a sciezure 2000 kms ago and had both cylinders off , one was damaged the other fine. they replated the damaged cylinder and fitted new piston and rings. unfortunatly they only fitted new rings to the ''good'' cylinders piston and not replaced the piston while they were in there.

the crank doesnt sound loud but there is a whurring noise and vibration coming through the frame and tank when its revved.


im gona run it with the tank off tomorrow and see can i locate the noise, if i cant i will remove both cylinders

i believe the top cylinder is fun ha

[arlurt]

Hi Chris,

I'm pleased you managed to get the pipes to fit properley, I trust you've passed the good news on to your "friends" at Nikkon.

It sounds great in the YouTube clip, I was surprised how many 3XV clips popped up when I started looking...

The vibration is a difficult one to call. It's cheaper to have a worn crank rebuilt before it fails than it is to have it fail completely, and then to have to find a secondhand one, and to have that rebulit before it goes into your engine.

All my efforts at finding a cheap fix have come to nothing. With what I've spent I could have just taken the engine out and sent it away for rebuild. But I like working on them, and like the engineering.

Once I've got my garage in order I can have a proper sort out and see exactly what I've got. I hope to be able to build up two complete dry-clutch motors. One with the ported cases & barrels, and an SP crank. One as a standard RS. I'll then go through the bits I've got left and decide what should be sold on to recover some of my costs, and what I'll keep as spares.

I've not found many TZ bits that are common to the 3XV. The engines look very similar but there are an lot of detail differences. The TZ base gaskets are a different shape to the 3XV. The crank I bought seems to have the same bearing size and cylinder spacing, but has a splined end rather than the key on the 3XV. So much for the 3XV SP having a TZ crank, maybe it's got TZ bearings...
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[eire_kp61]

finally got around to checking out this vibration in the bike,

I hotwashed the whole bike before any stripping down.




It was much quicker strip down then my old tzr 125 4fl
with the engine out in 20 mins or so .

after taking both cylinders off it was obvious that the crankshaft bearings are shot . lots of play in the top conrod and some wear in the cylinder as a result, the lower cylinder stil looks new.




Ive never rebuilt a v-twin 2 stroke before , is there any workshop manuals available or anything i should know before i start ?

are main bearings available through yamaha or where should i go,
i dont really wana strip it before i have the parts

Im gona change the pistons while im at it so will need gasket kits too ,
maby wossiner or someone similar has performance pistons available

i fitted one to the 125 and it flew

[Wb]

Hi. It might be worth popping over the the TZR forum at: http://www.neil.nu/cgi-bin/tzrforum/ikonboard.cgi?s=d7c8ad1ed69c2cb9dd8355928dee1c76 for some additional advice (Myself and others have posted plenty of info on 'de-restricting' 'em there too), but here's a couple of initial pointers to help you with the rebuild:

1. Download the relevant workshop manual and parts book from Alex's excellent resource site at: http://pure-2-stroke-spirit.info/filebrowser/3XV

2. Outer mains, con rods, big ends and end crank seals are the same as the early 3YL and 4DP V twin TZR's (and I think the later ones too, but I'd need to check that) - the TZ cranks are effectively the same (as the SP model crank) but for the end web plates and the center main baering/seal as Karl notes. Base gaskets are in fact the same (or at least directly compatible with) the V twin TZ gaskets too - though note that TZ ones come in a range of thicknesses. The stock 3XV one being the same as the .6mm TZ item. TZ bits can be had (usually next day) from Dennis Trollopes in Bristol so I normally get such parts from him as it's quicker than waiting on an order from a Yam' dealer.

Good luck with it.

Wb

[arlurt]

Hi Chaps,

The TZ base gaskets I got were a different shape to the 3XV ones. I'll take a couple of puctues and post them.

The point about TZ cranks and 3XV cranks is sadly true, I was trapped by people on some sites saying that the 3XV uses a TZ crank. Might be nearer the truth to say the 3XV SP uses TZ bearings...
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[Wb]

Hmmm. Maybe they were for the later 4TW TZ, which has a diff bore and stroke I think? You are fine with 3YL or 4DP base gaskets. They're what I use in mine as they are quicker to get than the 3XV ones (next day usually from D Trollopes) though you need to get the right thickness one of course ideally.

Yes, it's not a simple bolt in, but the SP/SPR crank is effectively a TZ one with different ends (and centre main/seal), but it would be a hassle to try to fit a TZ crank in a 3XV certainly - though if you had a good TZ center and were having one rebuilt I'd think you could perhaps put the 3XV(SP) ends on a TZ crank? Not sure about any problems with the center bearing though and have never tried fitting a TZ one myself, so I'd always recommend fitting a pukka 3XV crank myself. And an SP one rather than an R one too of course. There are no compatibility problems here, so if replacing an R crank, I'd always try to (in fact do) do it with an SP one for teh additional strength.

Cheers

Wb

[arlurt]

I took a couple of photos of the 3XV and 4DP base gaskets I bought:



The bolt spacing appears the same, but the gasket shape, transfer ports and coolant holes are all different. They both might seal in the right places, but they're not the same...
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[Wb]

Lol. That's splitting hairs a bit Karl. You'd probably find that different production runs of 3XV ones vary almost as much as that! Trust me, there's no problem in running the 4DP ones in a 3XV - they are all I ever use in my 3XV motors. And if you've widened your transfer entrance a bit , using the TZ one means you dont even need to take the scissors to the gasket either!

I've never once had a base gasket leak on any of my 3XV motors. And I re-use base gaskets numerous times too when doing any development work or testing too. Just fling 'em in, they'll be fine

As I said, I think the 3XV one is .6 so you need the appropriate thickness TZ jobbies if you want to keep port heights, squish and head vol exactly as stock. TZ ones are available in .5 - .8 thicknesses so allows you to adjuts port timing/squish a fraction if necessary

By the way that 3XV gasket is an SP one

Wb

[arlurt]

Thanks Wb.

I bought a few 4DP gaskets when they came up on eBay but was worried that they were a "different" shape to the 3XV ones I already had, it was the area around the waterways that bothered me most... I've got a couple more coming in my latest From Japan package.

The 3XV gasket came from my local Yam dealer. I didn't realise there were different ones for R and SP, how can you tell that's an SP one (other than the part number )? The cases are the same aren't they?

I've re-used gaskets on air-cooled engines but never tried to on a liquid cooled one. Do you just "help" them a little with some sealer?
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[Wb]

The -10 suffix on the 3XV gasket part number indicates that it's an SP part. Not sure what the difference is between it and the R one - thickness probably, but you'd need to measure up an R and an SP one to check as the manuals don't give the thickness as there are no optional parts.

The TZ one you have there is a .7mm one (the -10 suffix indicates that). The .6 TZ item is -20 and the .5 -30 (.8 - the standard fitment 4DP TZ gasket is -00).

I can't remember if the stock 3XV R one is .5 or .6 though? You should be able to measure an R and an SP one with a micrometer if you want to be sure - though it hardly matters TBH, as stock 3XV motors tend to run enormous (commonly 1.5 -1.6mm) squishes, so you won't encounter any problems on a stock motor running a .5 even if teh stock one was .8 - though you will affect port heights a touch too, so might affect power charecteristics very slightly (probably not enough to notice whjen riding, but a dyno might pick it up)

If the gasket is a new one you don't need to do anything with it - just fling it on. If re-using them, a very thin smear of good gasket compound will ensure a problem free cheap rebuild - in my experience at any rate. As I said, I've done it countless times without problem. Obviously, if the gasket is badly damaged you need to replace it, but if the surfaces are reasonable, they seem to be highly recycleable - which claws back some of the 'green points' I lose by having so many strokers

Don't worry about the slightly larger water holes in the TZ gasket. The thermostats in the road bike will have much more bearing on coolant flow than they will.

Cheers

Wb

[eire_kp61]

Been a while since i posted an update on this,

the day ofter i took the engine out i set about stripping it to get the crank out,

I must say it was the easyest engine i ever took the crank out of
Its almost as if it was designed so the crank was an easy remove item
just remove the cylinders and flywheel and take off the top cover and there it is







i took the trip to my local bike shop where i ust to work to enquire about parts

the owner said he knows someone who would look after that well and sent it on to a friend in the uk

so its the wating game now,

Ive ordered top end gasket kits already
I need to find a supplier doing racing pistons now so i have them when the crank comes back

ps karl i got my cd, thanks very much

[arlurt]

Hi Chris,

Pleased to see it's going so well, and to hear that the disk arrived OK.

Good luck with it...
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[muckerbarry]

How’s it going,
That looks like a clean bike you got,

I was surprised to find out there was another TZR owner from Kilkenny, I’m from the city (town) myself, I’m now living in Cork. I bought a 1991 TZR250R back in may, my first bike, I must say I was delight with it, ill get a few pics up when I get a chance.

Unfortunately it developed a death rattle last week, sounds like a big end, but I won’t know until I get around to stripping it. Who did you give you crank to get repaired? Was he in Kilkenny? And how much if you don’t mind me asking?