A couple questions about piston bearings + scoring

Peep the pick ^

Alright I've got this kit that seems to have too much play (5mm) between the needle bearings and the casting of the piston, my concerns are the bearings walking to one side or the other, and casing the set up to become out of balance. which I believe may have led to my second problem of four score marks on my piston equally distanced apart from what it seems. The score mark image is in the next post.

1204175245_bearing_gap.jpg

Re: A couple questions about piston bearings + sco

heres the wear mark, this really sucks, its a garelli kit so guys watch out for this bearing gap cause I suspect its the culpret

And what else I'd liek to know is if that gap is indeed causing this problem, should I machine spacers to go on the wrist pin, or should should I seek out a wider needle bearing, (probably not practical/possible)

1204175369_score.jpg

Re: A couple questions about piston bearings + sco

looks like it was running kinda hot?

Re: A couple questions about piston bearings + sco

could be it did soft seize once, I'm more curious about this bearing gap though, any insight on that one, would spacers in there cause too much friction? maybe they fit snug to the pin and this would not be an issue

Re: A couple questions about piston bearings + sco

Doug, I think that I have the same issue with my Athena Kit on my Sachs G3. I haven't been able to prove that this is the problem, but sometimes my engine vibrates a lot and then I'll come to a stop and take off again and it will not vibrate at all. considering that this is the 80cc Athena, the piston is alot bigger so there is alot more play around the needle bearing just like your picture shows. I wish there were wider needle bearings that came with these big kits or a place to source them at least. Does your engine have any vibrations either all the time or some of the time?

Re: A couple questions about piston bearings + sco

yeah I think there was a significant amount of vibration when I had it running.

I'll bring it around to t2, maybe we can think up a solution

Re: A couple questions about piston bearings + sco

John Joedicke /

Your fins a singing

Re: A couple questions about piston bearings + sco

daFishSticks /

it should be possible to find a needle bearing to fit. try taking your wrist pin and piston down to a local bearing house and see if they can measure it up for you, and possibly order something.

the spacers would work, it would make putting the wrist pin back in, an even bigger pain, and would have to be a press fit just like the pin into the piston.

Re: A couple questions about piston bearings + sco

yeah I was kinda worried that if I do put spacers on I can probably kiss goodbye the ability to remove it all after it gets exposed to the heat and wear. I try and check out the bearing supply thanks.

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