how to inspect intake/exhaust valves.

hey i own a 05 crf250x and think i may have bad valves. i pulled the head off and noticed that there is alot of carbon buildup on the top of the piston and around the valves. does this meen i need replacing? i was wondering how you could check for bent or worn out valves to see if they need replacing.

please help thanks

Mine looks like that too. I believe its normal. Did you check the clearance via feeler gauge before disassembly? Whats the problem you were experiencing?

well at first it wouldnt start so i checked the clearences then i reshimmed it. then i went to ride it and it started the first time but then i went to ride it again and it wouldnt start unless i bomb started it. i took it apart to look at the valves and there is alot of carbon build up everywhere. and also i can take the piston and wiggle it back and forth a little bit. is that normal?

pull the valves out and look at the angles. If they are cupped, they're toast.

what do you mean by cupped?

If the valves are submirged in their seats, they are cupped. You should be able to snag the valve with your fingernail if good as the valve with stick up a bit. Sounds like you need new intakes and possibly a new piston and rings. Oh, don't put that head back on without a new gasket. Carbon buildup is normal.

This is cupped Click Me!

typically excessive carbon build up is a result of bad rings. If you valves are moving like that you need to have the seats cut and put new valves in.

okay thanks

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now