I have an extra cylinder I want to send out for boring.  Are the bores supposed to be the same size at the recommended measure point of the skirt as
near the top ring?  I will be using a stock material type Yamaha piston. The book says 0.040-0.045mm clearance from most narrow part of cylinder to widest part of piston if I'm not mistaken.  W

After reading his name in a positive light on this forum a few times, I called Bill Bune Enterprises and he seemed receptive to do the work,
but told me to include the clearances I wanted.

I'm thinking same bore all the way down w/recommended Yamaha clearances.       

What do you think?  Any bad experiences with boring? 



 

  

 

Can't go wrong with BB.

shoot for book specs 40-50 microns 10 mm above skirt bottom perpendicular to pin axis

problem is how much is needed to bore?
They will bore/hone to the size that will clean-up