62T wrist pin bearing

[shockwave538]

I’m putting together a 62T engine. Using the crank out of my 61X that was running fine. Pistons and associated parts are all new from a buddy (who is currently unavailable), but didn’t come with thrust washers. When trying to install the new piston, including old thrust washers, there was not enough clearance to get it all in the piston. Compared bearings and the new one is .9mm loner than the old one. Read in some threads where larger bearings were used without thrust washers in certain years or from certain manufacturers. There’s nothing in service manual that discusses expected clearances in this area.

My dilemma is:

1) Use old bearings with thrust washers.
2) Use new bearings without thrust washers.
3) Use new bearings with thrust washers, which will require filing down slightly inside the pistons to obtain clearance.

REALLY want to avoid #3! Just doesn’t sound right. Would also like to avoid #1. If I do #2, bearing size is .50mm less than old bearing and washers combined. Seems like it would settle fine like that. Thoughts?

ProX piston kit 01.2510.100, states 94-08 SJ in box, online catalog goes even longer. References stock 61x Yamaha part number.
Bearing was WSM, part number was worn off package. Research shows it probably wasn’t part of the piston kit.

 

[Vortex]

I am going to try small pin Kawasaki bearings from jet maniac. They are longer and fit without washers.

 

[Mike W]

Use the new wrist pin bearings without the washers. New bearings are wider so you don’t use the washers.

 

[shockwave538]

Looks like the new bearing is .5mm shorter than the old bearing and washers combined. I put them both in the rod with the wrist pin, and there was the same amount of play (or lack of) on both. I know either would center and settle out, but the old one would have less play axially. It looks pretty good and shows no wear, so I’m thinking of going with the old bearing.

 

[JetManiac]

Use the new ones!

 

[oside-tanner]

The wrist pin bearings sold for the Yamaha 650 engine was wider and doesn’t use the thrust washers. When the 701 engine came out, Yamaha went with a narrower wrist pin bearing but added trust washers. Different builders has there own opinion as to what is better. I personally use the wider bearings in all my engines.