i bought a 2004 yz250f this june, obvioulsy used
i am looking for some suggestions on upgrades
where should i start???
i plan on rebuilding my top end this winter>>> any suggestions as far as upgrades, as long as im in there???
First thing is to get the valves replaced with Kibblewhite stainless steel. This will help ensure the life of the valve train for a couple seasons (as long as you do periodic clearance checks and adjustments). It wouldn't hurt to send the head off to a knowledgable engine builder such as Eric Gorr (altho there are many more in the area- I just prefer his work) to make sure everything is up to spec and maybe have him clean up the porting a bit.
The cam will probably also be pretty close to it's life expectancy so you may want to consider a hot cam.
Do not go cheap and leave the current timing chain in replacing it as long as the engine is apart is cheap insurance.
Waterpump should also get a good looking over as long as you are inthere.
Replace anything that looks at all questionable- nothing worse then putting it all together to have to tear it down a week later for something you thought would make do.
Grensjos, for the water pump check the seal behind the impuler and check the impuller it self. A boyseen QUICKSHOT will help in keeping your new top end cooler. Also, an exhaust would be great for more power. In your price rang i might think a slip-on is best.