Originally Posted by
kenh3497
I was given a Stihl chainsaw that had compression but the cylinder was cored. Cause.... The wrist pin circlip broke. It was a single tang clip. The other good side broke as i was removing it. I've also seen this happen in some of the .15 racing engines we used in Quarter Midget of years past. Many possibilities... Wrong temper of the material, bending past the yield point of the material or any combination of factors.
My guess is a bad batch of clips snuck through QC and they will run their course and all will be happy again.
Ken
That is a common fault with that type of circlip.
I'm pretty sure this is the circlip in the GT33's and it would be extremely unusual for this type of circlip to fail unless a side force has been exerted to the circlip. Even then, it would take a lot of force and I can't see how that would happen. There is nothing that can brake off due to vibration.
But Matt has had two failures now and RM has had one, so something is not right. I would suspect a groove problem more than the circlip failing.