i adjusted my valves about 400-500 miles ago, and now in the winter they are screaming again, and i don't feel like adjusting them now, will this cause damage or is this more a noise annoyance, cus it has gotten quite loud, and i don't really understand why they need to be adjusted again, i tightened the nuts very good

 

If they have gotten that loud you should check them again. you might spot something else going on. Valves really are something that can go for years before they need resetting. Plus if they're off a just a bit the noise isn't as bad as your description. Last trx300 I worked on the timing chain was making all the noise. A little different on the Rancher because of the push rods and the timing chain is lower in the cases. Might check your timing and gas to make sure it's not detonation(sp?).

Also set the valves with the engine is overnight cold.

Good luck.

 

how do u adjust your valves?

 

If your 250ex has push rods then.....

1) remove valve cover (or the 2 valve covers if an older model)
2) rotate engine until you see the valves wobble (exhaust is closing while the intake begins to open)
3) rotate engine 360 degrees (check the engines Top Dead Center (TDC) mark on the flywheel if needed.
4) use a 10mm wrench and a small screwdriver to adjust the valves. The 10mm hex nut locks the adjusting screw in place. Usually set a bit tigher because when you tighten the lock nut it sucks up the screw. Use a .006" (six thousands of an inch) feeler gauge. Go no-go feelers work well.
5) reassemble.
6) check again in a few years.

Hardest thing is getting to the stuff. Might be easier with the gas tank off. Usually not a big deal to remove.

If you're going to do this stuff please invest in a $30 shop manual. Ebay...worth it.

Good Luck,
rob