1994 YZ 250 - The good the bad and the things to look for

Hopefully you have a manual...if so, follow it step by step..if not, buy one. I had a '89 or '90 YZ250 years ago and it was fast as hell and reliable. If you rebuild it correctly, keep the air filter clean, and run the correct fuel ratio, that engine should be good for many hours.

Good reliable bike, scary fast at times. No particular problem areas, other than that they are not particularly fond of cast OEM pistons. Run a forged piston if possible, and have fun, and BE CAREFUL, lol.

I have a '95.

Fresh top-end (cast piston). Boyesen RAD valve, flywheel weight, down 1 on the pilot and 2 on the main but I think you have a different carb. Pro-Circuit Platinum pipe and FMF turbine core2 I think with the spark arrestor. I run it 30-1 per the manual and make sure I am running 95+ octane as it WILL detonate with less.

I have tried ATF, gearsaver and 10W40 motorcycle oil in the tranny and the 10W40 is by far the best choice IMO. No false neutrals and much smoother clutch operation and shifting.

Check for wear on the waterpump drive gear. It is plastic and can/will wear out.


Suspension-wise, I replaced the fork seals and the fluid. Set it to stock specs and tuned from there, the rear shock is stock with a fresh recharge and again, set to stock settings and played with it from there. I did not deviate much from stock as my (lack of) abilities were in line with the factory settings for the most part.

Stock gearing. Good bottom end with a big HIT in the mid and a decent top. This bike pulls hard.

So far it has been bullet proof as their reputation has shown.

I used 4.... steel wool and Bleach White on the plastic to really freshen them up.

I also have just purchased 94 to convert to a Ice racer ( a sport that is becoming big where i live ) and have many questions, but if some one has or knows of a pdf manual let me know, thanks in advance.