94 YZ250 Peter Jackson project

[chippy]

Ahhhhr, Peter Jackson, those were the days. I loved a good smoke back then.

[rocketfrog]

A little while back there was a complete 0w250 bottom end up for grabs, the owner was looking to trade for 0W63 bottom end.

Obviously there would be folks with that sort of hardware hanging around but I dont know any!

Looking at the photos of the early 90's era YZ250''s I notice that the 0W style clutch cover and right outer case at least were used among Yamaha backed teams in Oz. If you take a close look at the PJ bikes you notice a smattering of trick parts like Magnesium calipers and engine outer cases.

I like to see what works relics turn up on that site, totally out of my league to own, but way to cool not to have a look at.

[James Lee]

The trouble is for me and to be completely honest,I wouldnt have a clue what Im looking for in those respects,I dont even know what an OW250 bottom end is.
If you see any trick parts come up to suit this bike and were used back in the day please let me know.Im not rich or anything but would be able to spend a bit here and there without the wife finding out .
I was thinking of trying to find an Ohlins shock as the stock one I have needs a rebuild anyway,Ive sent an email to CDR to try and find out what shock and pipe was used on the bike and to see if they have any pics they could send me.
I picked up the bike from my mate yesterday and tore it down,there were a few rude shocks for me,this was supposed to be a clean original bike,different bolts everywhere,welded gear lever,cracked and repaired sub frame,rear rim cracked,nothing that cant be repaired though.
Might be a good time for me to learn how to lace wheels I think.

[rocketfrog]

Well worth learning to respoke wheels, and to be quite honest, it is not difficult to do. The straight pull spokes used on your 94 are the easiest to deal with. Conical hubs with angled spoke heads are probably the most difficult you will find on a Jap MXer.

Companies like magnum make affordable stainless spoke kits for your model at around $80 US per wheel, alternatively OEM are still available for even less if you get a deal on Ebay. Rims are readily available for late model disc style wheels, just make sure the spoke nipple holes match the nipples your going to use. For example, some aftermarket rim manufacturers make rims suited to oversized spoke and nipple sets - just something to be aware of if you are planning on mail ordering your parts.

Go to youtube for heaps of great vids on lacing and trueing - a few practice goes, some reading and bit of ingenuity to make a basic trueing stand and its all gravy.

0W or zero W is the designator given to Yamaha Factory works bikes and parts. Check out some of the historical 0W models like the Classic Hannah 0W40 at Terry Goods' website. Most of the 0W bikes were coded with a 2 digit numerical code to signify the year and capacity, however Donny Scmidts' world championship Factory ride was simply called the 0W250 see mxclassicworksbikes for some real Yamaha works porn.

[rocketfrog]

Grab a copy of Eric Gorrs book on tuning and set up. The title escapes me right now, but there are several chapters which provide great detail on little tips and tricks to fix the few shortcomings of your model. Reworking the combustion dome and changing the clutch spacer to the old 2k7 Item are a couple of simple improvements for that bike IIRC. Another was a Devol rear susp link to improve the action in the rear as well as some minor jetting recomendations to complement the dome rework. Lots of info out there for your bike and it was popular in the day for a good reason. Do a google on Eric Gorr and see what turns up.

[Nathan S]

There's a lot of interchangeability in YZ rear shocks. Check carefully before spending any money, but it's possible that an Ohlins intended for a later bike will fit your bike.

[James Lee]

Cool thanks for the info guys.Ill have to spend a bit of time researching the net,the OW bikes are unbelievable,The Hannah 465 is awesome.Not good thinking about my next bike before I have even finished my others .

[James Lee]

I just got a new piston in from my local shop,he measured the bore for me and it was 68.03mm so told me its on standard bore and needed a 68mm piston,when the piston arrived it was a 67.95mm,is this correct?it is supposed to have 3-4 thou tolerance.

[rocketfrog]

The pistons are colour coded to signify the finished dimensions. The intention is to measure the bore and select fit to suit. Manufacturing tolerances (plated cylinder) vary which makes it necessary for the pistons to be available within a range to achieve the correct piston to cylinder clearance. Obtain the YZ250F1 owner/workshop manual to verify which part number you need to order for your cylinder.

Check out the link below to search for parts for your bike.


http://www.partzilla.com/parts/search/Yamaha/Motorcycle/1994/YZ250F1/CRANKSHAFT+-+PISTON/parts.html

[rocketfrog]

Is the piston you bought OEM Yamaha or an aftermarket?

[James Lee]

Its a Woosner piston and the cylinder has been sleeved so needs a bit more clearance than the plated ones from what I understand.
I just didnt understand why they sent a 67.95mm piston when we ordered a 68mm but thats how they come apparently,they should just call it what it is,a 67.95mm.
A bit confusing,hope it will work.

[rocketfrog]

At about 0.0031 inches clearance on a forged piston in an iron lined cylinder you will be on the right track.

Wiseco recommend 0.0025 inches for the same set up, half a thou is not an issue.

[James Lee]

Thats great news,thanks rocketfrog.
Im in the process of getting my mates sand blasting cabinet going so I can strip the frame and get this project moving on.
Will be splitting the cases today to fit new mains and seals so hoping for no nasty surprises.

[James Lee]

Just a quick update,the bike is coming allong very slowly and after buying another bike with all the parts I needed and heaps of other new bits its been way more work than I expected but I'm happy with the way its turning out.
I've tried everyway possible to contact Mario to do the seat cover for me but just never calls me back so I'll just put the bike together with what I have here for now and look at doing a seat cover and plastics in the PJ colours later.
I'll post some project pics shortly,got a few spare hours so heading to the shed now to see what I can get done.