thumper135
Member
- Sep 20, 2009
- 33
- 0
Hello everyone.
I am going through a engine rebuild of my 99 Yamaha rxz135, the last oversize piston was pretty well scored so the bore had to be resleeved to be able to get back on the standard sized piston. decided why not go the bigbore route, although the bump from 56mm to a good 62mm was something i was not 100% about, but reasons i went for it was because 62mm was the most easily available 2 stroke piston with equal pin center holes, and also required not many modifications other than new ports being drilled and evening the dome.
Today I got the Cylinder back from the machine shop with the new 62mm sleeve. Piston to cylinder Clearance in between 0.05 to 0.08mm. Alright? The Ports of the Piston do still need to be modified, not too inclined to get the Cylinder ports enlarged, unless ofcourse Its something I absolutely should do. they will though get a good polish.
The Squish Band, other head modifications and head Gasket thickness is also one part I am not so sure about when it comes to actual figures, I know the head needs to be shaved, just not sure how much, advice welcomed. :-)
Left will be the old oem 56mm Piston, right the new 62mm with less height but more dome.
I am going through a engine rebuild of my 99 Yamaha rxz135, the last oversize piston was pretty well scored so the bore had to be resleeved to be able to get back on the standard sized piston. decided why not go the bigbore route, although the bump from 56mm to a good 62mm was something i was not 100% about, but reasons i went for it was because 62mm was the most easily available 2 stroke piston with equal pin center holes, and also required not many modifications other than new ports being drilled and evening the dome.
Today I got the Cylinder back from the machine shop with the new 62mm sleeve. Piston to cylinder Clearance in between 0.05 to 0.08mm. Alright? The Ports of the Piston do still need to be modified, not too inclined to get the Cylinder ports enlarged, unless ofcourse Its something I absolutely should do. they will though get a good polish.
The Squish Band, other head modifications and head Gasket thickness is also one part I am not so sure about when it comes to actual figures, I know the head needs to be shaved, just not sure how much, advice welcomed. :-)
Left will be the old oem 56mm Piston, right the new 62mm with less height but more dome.
Last edited:
