What happened to my engine?

66CC2019

New Member
Joined
Nov 7, 2019
Messages
8
Hi all, I have china 66CC engine, and while riding about 28 MPH i felt a small tug, then the engine lost all power, and died.... I tried to restart it, and it felt like low compression as the motor turned over a little easier then i remember. I pedaled home about 3 miles, and decided to take it apart to look for damage. I did not have to look far! So I have a new cylinder, piston, and gaskets to hopefully get up and running again. I only have about 232 miles on this bike and has been mostly trouble free. On another note, what broke? The only thing is seen was a little broken spring holder for the piston, (See picture) It seems like alot of damage for such a small piece? What are your thoughts on this? The bottom end is still tight and moves freely. Note also that broken spring piece was sitting on top of piston when i took the head off...... Thanks!


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GreasyChris

Well-Known Member
Joined
Jan 3, 2019
Messages
783
The circlip for the wristpin broke off and yes that's the normal damage it does when it happens. I had the same thing happen to me last year and same kind of damage. You're best off to use a better quality circlip like a 10mm malossi or a wiseco cw10 both can be found on Ebay
 

66CC2019

New Member
Joined
Nov 7, 2019
Messages
8
The circlip for the wristpin broke off and yes that's the normal damage it does when it happens. I had the same thing happen to me last year and same kind of damage. You're best off to use a better quality circlip like a 10mm malossi or a wiseco cw10 both can be found on Ebay
Thank you for the reply!, I will have to look into these circlip. The new piston comes with new ones, but i should use a high quality one. I'd hate to have to repeat this.
 

Greg58

Active Member
Joined
Jun 3, 2012
Messages
441
When installing the clips with needle nose pliers only squeeze the clip enough to get it in the groove, if you put too much pressure on it you can bend it and cause it to be loose in the piston. That's probably what was done wrong when it was put together originally.
 

Tyler6357

Active Member
Joined
Sep 28, 2011
Messages
757
That has happened to more people than I can count. Greg is right, you have to get the wrist pin clip in there correctly without bending it. You will need a new cylinder, piston, rings, clips, and I would go with a new head gasket too.
 

Akutey

Active Member
Joined
Dec 10, 2018
Messages
170
Split the case and do a thorough cleaning. Those bearings are potentially contaminated.
 
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