here is a couple of pics of my buddies 03 cannibal, it is kind of strange how it broke, right at the bottom of the stem, it rattled a little bit, enough to do damage. I have some spare parts and hope to have it complete by tomarrow night. He said it popped and then just locked up, well it makes sense, i know that it has happened before any ideas on why, thanks agian Brian
here is the piston, it did not punch holes in anything. I told him to pull the plug and look at it, he called me back and said that the electrodes are smashed flat, not good.
The problem was probably caused from running the 11,600 rev limiter.The valves float very close to the 11,600 rev limiter and after time the valve springs fatigue along with the valves causing the valves to float at a lower rpm and can cause it to hit the piston or fatigue the valves to the point of breaking.
It could also happen from not enough valve clearance.If the valve doesnt seat it will heat up and could stick.It sure looks like it was running for a long time without a good seal before it broke off finally.
is this y atk told me that when thy do the umm updats to the motor. that thy do a lap job to the vale. he said that cannondale just took the vale out of the box right to the heads no lapping???
I won't argue the fact that a "weak" spring could cause a valve to float and consequently make contact with the piston, but the inherent valve/stem design allows them to separate too. The stem is very poorly joined to the valve disc and is also under cut at the base where it is fusion welded to the disc. Further investigate the point of failure. I would not be surprized if it appears to have sheared off at the base. This would be indicative of a failed weld. If the steam is bent the valve probably was in contact with the piston.
I got one just like it. It came from PDavis's second motor, the one from the Spring Ride. He also had exhaust cam damage that ate into the valve bucket as well. I think the valve clearances were a little loose in it, to say the least.