01' yz125 wrist pin bearing question

[Garage_Dog]

I'm rebuilding a 2001 yz125 for a friend's son.  Its just a ditch bank bike so I'm using a Namura top end kit.  The wrist pin bearing that came with the kit is not the same size as the one I removed from the bike.  A OEM bearing is now on its way and Im hoping that will fix the problem.

Why is the Namura bearing smaller?  

Does anyone know if the original bearing in the picture is  OEM or something else?

 

-thanks

 

[twostroke-notbroke]

I had this problem and used the old bearing.

[Garage_Dog]

Ok, thanks.  That makes me feel a little better.

 

[Tankslap]

Have you looked in the underside of the new piston and tried to see how each of those bearings fits in it with the wrist pin in place?  Wondering if the piston has a wider gap than OEM, where the OEM bearing would have some lateral play compared to the new one.

Can't tell from the pic if the new bearing is also fatter than the OEM one.  Does it fit in the connecting rod, and fit snugly on the wrist pin?

[Garage_Dog]

The outside diameter of the new bearing is smaller.  When I installed the bearing on the pin, it fit snugly.  But there is considerable movement up and down against the rod.  As soon as I noticed that, I didn't even think of the width of the bearing.  I'll check that too when I get off work.

[Tankslap]

39 minutes ago, Garage_Dog said:

But there is considerable movement up and down against the rod.

Wow, not a good sign.  Good thing you noticed and have OEM on the way, though still wondering how the OEM fits within the underside of the piston.

[ossagp]

Wrong year probably. If you go look you will see that yamaha did some size swapping (all this from memory) or you can go to Wiseco's online catalog and look at the different pin diameters.  It will illustrate it to you.   

[YZDOC]

Sorry you are using a namura top end. Be ready to rebuild sooner than you think. Bearing same 99 up for Vertex, Wiseco, Wossner. 

[ossagp]

Wiseco shows the same pin diameter for a very long run of years.  However the wrist pin bearing was apparently different:  1997 they show the same part number on the wrist pin bearing.  2001-2004 show a different bearing number.    Rod ends and needle bearing pin games.  

[Garage_Dog]

Yep, you are right.  

Thanks for suggestions.

I figured it out.  I ordered 01' bearing and the bike is a 2000.  duh.  

The OD is larger on the 00'.