Jump to content

YZ125 new piston, need help!!! Side to side play

Recommended Posts

I scored a piston while riding it was a lean issue. The piston was scored on exhaust side the crank is fine. The old piston had side to side movement on the wrist pin. So does the new one!!! Hot rods crank. New piston kit roller bearing didn't fit was too small, even with the old correct fitting roller bearing on the wrist pin there is still play the piston moves side to side 

Share this post


Link to post
Share on other sites

Gotta have those holes on exuast side of piston.  Ring stop pins always go towards intake.  Yamaha pistons tend to come pre drilled but if not you wanna do it . Weisco pistons come with instructions or probably video on here. :ride: i seem to be only doing them in honda oem pistons now days

20170816_090627.jpg

  • Like 1

Share this post


Link to post
Share on other sites
9 hours ago, Samcwach said:

There is a hole in the piston on intake side to oil rod but not on exhaust side. No vertical play.

 

2 hours ago, Motox367 said:

Gotta have those holes on exuast side of piston.  Ring stop pins always go towards intake.  Yamaha pistons tend to come pre drilled but if not you wanna do it . Weisco pistons come with instructions or probably video on here. :ride: i seem to be only doing them in honda oem pistons now days

20170816_090627.jpg

Yep, what moto said and see his piston photo... gotta have as the bridge will warp with heat. 

  • Like 1

Share this post


Link to post
Share on other sites

Correct. The hole(s) go on the exhaust side. Their purpose is to oil the bridge. It will die without it.

Also correct that side to side play on pin is normal. Check manual for tolerance, but they do slide a lot.

  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


×