Wrist Pin Bearing 250/300


New member
If you're replacing a top-end on a 250/300, the Vertex replacement kits do not include the wrist pin bearing - not sure about Woosner? Seems whacked to me that a top-end kit does not include this bearing?

The bearing measures 18 x 22 x 22mm - caged needle bearing.

You can buy them here for cheap:


North Tahoe Motorsports does it right and sells you everything you need in their kit:


Dealt with both vendors before, and both are first-rate.

Most piston kits don't include the little end bearing.
The ebay link you posted includes it because its being sold as a 'top end kit', whereas wossner/vertex/wiseco etc usually sell 'piston kits', which is the piston/rings/pin and clips only.

It has been discussed on here previously, some trains of thought suggest that seeing as you aren't replacing the rod or rebuilding the crank, why would you replace the small end bearing, which deals with arguably less stress than the big end does.

Then again, seeing as you're there, why not replace it. Like you say though, they are cheap and common enough. That bearing is used in lots of other 250 2 stroke engines.