Diff'rent Strokers

kiwi mvx · Joined: 14 Jun 2008 Posts: 15

Hi Guys,
greetings from the southern hemisphere. Iv'e just found this fantastic website, what a revelation!. It can be a dark and lonely road you head down when you choose to ressurect a mvx.

I always wanted a mvx 250 when they came out here in New Zealand ($3299 NZ dollars), however I couldn’t afford one at the time. Many years later I found one for sale in for $600 NZ dollars, I couldn’t believe my eyes... I brought it sight unseen, over the phone.

The bike is very original with 22,000km on the speedo, the only reason it is in such good condition is it had been in storage for about 15 years. The bike was a runner when I brought it. However, I started it and turned it off after about two minutes as it sounded like all bad news; knocks, rattles, scraping noise, detonatiion etc.

I stripped the engine down and located a matching set of barrels and pistons, and a good set of conrods etc. The one part that has stopped the rebuild is the two internal crank seals. i believe Honda never listed the crank seals as a separate part, you had to buy a complete crankshaft assembly, which I guess would be like finding chickens teeth these days.

Everyone I talk to about it has either (1) seized a mvx or (2) knew someone who has seized one at some stage. that aside I still have a unhealthy obsession with mvx’s and cant wait to get it back on the road. I have not seen a mvx on the road for at least 10 years here in New Zealand and I am really keen to get mine up and running and use it. Any ideas or suggestions where I could get some new crank seals or a complete crank with good seals would be much appreciated.

Kind regards

David Ede

Alastair · Joined: 13 Jan 2007 Posts: 62

For €1,591, Honda will sell you a new one - http://www.cmsnl.com/searchparts.php?s_product1=&s_product2=KG4&s_product3=&partslistPageSize=25&totalresults=

Alternatively, I did point someone on this board to a new one for £125. They bought it but did nothing with it as far as I know. Do a search and contact the guy.

Alternatively, a decent bearing factor should be able to supply similar seals with an adhesive to secure in position.
_________________
Alastair

CBR1000RR6 (0 - Court in 2.5 seconds)
NS400RF
MTX80RFD

Crofty · Posted: Mon Jul 14, 2008 9:48 pm Post subject:

Hi, check out Yahoo Auction Japan, found this there....
http://babelfish.yahoo.com/translate_url?doit=done&tt=url&intl=1&fr=bf-home&trurl=http%3A%2F%2Fpage.auctions.yahoo.co.jp%2Fjp%2Fauction%2F112639023&lp=ja_en&btnTrUrl=Translate

You will need to use an agent (EG fromjapan.co.jp) to ship it to you which will cost extra, but their web site is pretty easy to follow, check it out.

Thats about NZ$3500!!, nice one tho'!!

Welcome to the forum.

Loads MVX stuff, cant find a crank, some new old stock panels etc, and this too....

http://page16.auctions.yahoo.co.jp/jp/auction/u25664193

Gary
_________________
Breathing new life into an old Gamma!

http://www.rg250.co.uk

kiwi mvx · Joined: 14 Jun 2008 Posts: 15

After searching the globe for crankseals, I did find the original manufacturer based in the USA who was prepared to make a limited run of crankseals. the dimensions quoted were 52 mm x 36mm x 6mm Nitrile 80. The catch was they would only make a minimum of 90 pieces with a lead time of 19-20 weeks at a cost of $2.12 American dollars each. Eventually I sourced some equivalent seals in New Zealand which are very close in size which appear to be doing the job. Three donor engines have been used to source enough parts to build a good crank and find suitable combinations of barrels.

http://s460.photobucket.com/albums/qq328/kiwimvx250/?action=view&current=PB180503.jpg

With the motor finally reassembled it was time to put the bike back together.this involved new fork seals and fork oil and a new set of tyres 120/90/18 Pirelli Demon rear and a 100/90/16 Pirelli Demon front. The four sets of carburettors I have ranged from 125, 128 or 130 main jet combinations. In the interest of preserving my engine I changed my main jets all to 130 and set the oil pump on it's richest setting using TTS synthetic two stroke oil. I put NGK BR8 plugs in the front two cylinders and a cooler BR9 in the rear cylinder. The bike started immediately and ran evenly on all three cylinders. Huge relief.

The engine was assembled with second hand pistons and rings as a result of difficulty sourcing a complete set of pistons to match my barrels. Initially the engine was quiet running however with about 900 kms on it know I think the high spots have worn of f the pistons and things are sounding a little rattly. The motor still seems to make good power which kicks in at about 7000 and signs off at about 9500. On the bike it sounds like youre going alot faster than you are, however it does get up to 160 kmh reasonably rapidly. On the open road head winds take the edge off the performance, i.e alot of 4th and 5th gear 4th gear changes, all part of the fun.

The handling of the bike was probably the biggest surprise, with a claimed dry weight of 138 kg the bike is light and flickable with tons of conering claerance with the higher profile tyres. I run 5 psi in the front forks and 32 psi in the rear shock. I am still experimenting tyre pressures and fork pressure, however the handling is bloody good to say the least, even the front brake is better than I recall back in the day.
http://s460.photobucket.com/albums/qq328/kiwimvx250/?action=view&current=P1080456.jpg

[img]

Since getting the bike up and running I have sourced a set of genuine honda .25mm oversize pistons and rings. I have a set of barrels on standard bore size so over the next few months I will get these bored and put a new set of pistons in the hope of keeping this engine in in one piece. I thought when I was building this bike that i would take it easy on the engine and ride it conservitively , however in relality you can't ride these bike slow, youv'e just got to ride them hard all the time up and down through the gears to enjoy them, which is I guess what they were originally designed to do. I am regularly riding the bike and enjoying every minute of it.
Finally, if all my bikes got stolen out of the shed, the mvx is the one I would most want back.

belfastgeoff · Joined: 12 Mar 2008 Posts: 44

nice one mate

Craigside_Pete · Posted: Sat Jan 10, 2009 2:25 pm Post subject:

Brilliant write-up and good to see one of these brought back to life!

Looks like you won't run short of chassis spares for a while!!!

Alastair · Joined: 13 Jan 2007 Posts: 62

Well done. The bike looks great. Please PM me the details of the US seal supplier. I'd like to make enquiries for NS400 crank seals.
_________________
Alastair

CBR1000RR6 (0 - Court in 2.5 seconds)
NS400RF
MTX80RFD

belfastgeoff · Joined: 12 Mar 2008 Posts: 44

good thinkin alastair on the ns400 crank seals mate