Wrist Pin Bearing
 

Hi guys,
Need answers quick. I'm rebuilding the top end in my bike after it siezed last weekend (ring pin failed, ring rotated and then got caught in the exhaust port....ouch). I forgot to order a new wrist pin bearing to install, so I need to know (1) how much play is acceptable in this bearing and (2) will a Honda CR250 wrist pin bearing fit (which year?)? Let me know ASAP.

Thanks,

Steve

Reuse the bearing.
They really don't wear out.

Seriously? It feels really sloppy in the little end of the rod.

It will if the wrist pin is not inserted as well, as the needles move in the cage slightly.

Figured that out. Once I put the wrist pin in, everything was nice and smooth.

haha. dad tried to tell me that my new wrist pin bearing was worn out as it had movement when it wasnt running on anything... doh, it needs to be between the pin and the rod to measure the play. the one i replaced looked brand new if not a bit blackened. no play at all

When you think about it, whats the point of replacing the bearing if your not going to do the rod kit as well?

The wrist pin bearing hardly sees any action.
In comparison, the crank rod bearing is always spinning, while the wrist pin is rocking back and forth.
In some automotive applications the wrist pin is fixed, with the pin floating in the piston with no bearing.

Consider that the primary load on the bearings is due to the compression and combustion. The bearings are loaded the same when the engine fires. The rod bearing has much more surface area to distribute the load. The wrist pin bearing is proportionally higher stressed with the same load.

4 strokes dont have wrist pin bearings....