Yd100 needle bearing slop

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Jan 18, 2017
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Hi everybody, I took apart my yd100 today to give it a windowed piston and noticed that the there is a lot of space between the piston and the needle bearing sitting on the wrist pin. So much that with the needle bearing slid up against the piston the crank arm loop has only ½-⅔ of needle bearing under it. I'm sure even if I center that bearing under the crank arm it is going to decide it wants to live up against one side of the piston. Does anyone else experience that. To me that doesn't seem like that bearing would last very long. Anyone else see this on theirs and what are your thoughts??
 
What kind of connecting rod does your motor have. Mine was a zmn100 rod which only takes a 12mm wrist pin and needle bearing so you might have to send back that window piston and the order a new one that comes with a 12mm wrist pin and needle bearing the yd100 connecting Rod is made for a 10 mm m wrist pin and needle bearing.idk if that's helps or not but hopefully it should.
 
There are longer needle bearings that only allow 1/4 of it to slide out. I don't know if you'll be able to see it but I will send you a picture or try anyways hold on...

If you look closely you can just barely see the end of the needle bearings and that is all that sticks out from underneath the Piston except the end of the race which just is a little bit more then what you can see in the picture instead of 1/2...like I said it only comes out like maybe a third if that. Maybe a 1/4? Idk.

But answer your question yes there are different needle bearings some better than others.
 

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There are longer needle bearings that only allow 1/4 of it to slide out. I don't know if you'll be able to see it but I will send you a picture or try anyways hold on...

If you look closely you can just barely see the end of the needle bearings and that is all that sticks out from underneath the Piston except the end of the race which just is a little bit more then what you can see in the picture instead of 1/2...like I said it only comes out like maybe a third if that. Maybe a 1/4? Idk.

But answer your question yes there are different needle bearings some better than others.
Sorry about the crappy pictures but I already have it installed and I don't really feel like taking it out. My bad.
 
Hi everybody, I took apart my yd100 today to give it a windowed piston and noticed that the there is a lot of space between the piston and the needle bearing sitting on the wrist pin. So much that with the needle bearing slid up against the piston the crank arm loop has only ½-⅔ of needle bearing under it. I'm sure even if I center that bearing under the crank arm it is going to decide it wants to live up against one side of the piston. Does anyone else experience that. To me that doesn't seem like that bearing would last very long. Anyone else see this on theirs and what are your thoughts??
See my post for an easy solution
FREE needle bearing spacers 4 high
 
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