wrist pin bearing failure

[Tim_B_172]

This happened to my old man's engine. After his engine stopped suddenly and locked up, he took the cylinder off and found that the piston was extremely loose on the connecting rod. Further investigation showed that the little needle bearing on the wrist pin had come apart and the rollers are everywhere inside the engine. It looks like he will have to split the case to get all of them out. My questions are: Has anyone else had this happen? Is there a way to prevent it?

Also:
I have the same model engine, redbat 66cc, and when I took mine apart to clean up the ports I noticed that the wrist pin bearing can move back and forth on the wrist pin. It didn't have any vertical play, seemed nice and tight, but if you move the piston side to side on the pin, you can get the bearing partly out of the connecting rod. Does that make sense? and if so, is that normal? could it contribute to a failure of that bearing?

 

[Drewd]

Yes, yes, and yes (but shouldn't be normal for these engines but is)

 

[Goat Herder]

A member here here by Foureasy has better bearings than the stock ones I believe.

http://motorbicycling.com/members/foureasy/

 

[Tim_B_172]

Shouldn't be normal but it is? I'm not sure I understand, are you saying that they are all made this way, but it's a bad thing?

This redbat engine of mine is only my second engine and the first one that I've had the cylinder off of. When I got the first engine, I didn't know about cleaning up the ports so I never took it apart. Which is why I didn't know if it was normal or not. Either way it doesn't seem right.