Roller Wrist Pin Bearing (vs. bushing)

[rcjunkie]

Well, just an update on my roller bearing conversions. Both of my personal bikes and 2 of my spare engines and a couple of customer engines have been converted from bushing bearing to roller bearings.

So far so good. I have about one tank of fuel on my bike and it runs great. I could blow smoke up your a** and tell you that that the bike runs smoother, rev's higher, and pulls stronger but I really can't tell a difference. I can tell you that I am very sure that the bearing will easily last as long as other engine components and that a 50:1 mixture should be fine but I will run mine at a 42:1 only because it is easier to measure out 3 oz per gallon.

I still have 6 bearings left from my last order and if you wish to purchase one, check out my classified ad. I personally feel the engines should have these put in at the factory and is a must for every new engine install.

 

[OldPete]

A wrist pin bushing should not have a thick wall, it should be thin and made of bronze with a high tin content or aluminum bronze. I think these failing thick rod bushings are thick because a roller bearing was meant to be there and to cut a corner to $ave a few pennie$ a bronze bush with low tin (tin is expensive) content was used. This type of bushing is soft and will squoze out (deform) under load. Preignition, detonation and lugging the engine offer very high loads to the wrist pin bush.

Pic of a proper wrist pin bush.