kips valves snaped off

[aiden hallam]

Can you help, ive just finished rebuilding my 92 kdx200, due to a broken left hand exhaust valve. The bike has had new valves and idler gear and went back together all ok.
The problem is the bike has covered about 200 miles since the rebuild and the same thing has happened again. The bike lost performance so i checked the valves, the rod was stuck closed so off comes the head again, the left hand exhaust valve has snapped in half again and broke off some teeth on the gear.
Dose any one know the cause of this problem, the bike runs on good oil at 32:1, on inspection of the valve it looks like new still, apart from being in two bits so i dont think the lower half seized in the cylinder so whats going on ?
Im going to buy a new valve and rack, but before instalation can you please help cheers Rich

 

[Fred T]

check with www.frpoffroad.com

 

[Boot]

Don't know why the valve would actually snap, but I do have some thoughts on this general subject posted here:

http://www.copperleife.com/craig/bikes/kdx/pvalve.htm

Maybe it will give you a clue as to what's going on with your bike.