HOW TO: HONE CYLINDERS
The reboring process is not complete until the high spots from the boring bar have been smoothed
Tidy up lightly scored barrels or super-finish a rebore
Once a barrel has been rebored, the next step is to hone the liner to make the surface more suitable for the piston rings to run against. That’s because when a barrel is bored, it’s essentially similar to cutting a thread and you’re left with a rough, helically cut surface. The familiar cross-hatching you see on a newly finished or unworn barrel is the result of honing.
The process creates lots of little peaks and valleys to hold a thin film of oil to help prevent the piston rings seizing in the bores. Not that it takes much to go from freshly bored to properly honed. The hone should take no more than a couple of thousandths of an inch off of the bored surface. Often when boring a barrel an engineer will take account of the honing process to come and under-bore slightly.
Pete O’dell of The Motorcycle Works took us through the various approaches to honing to explain how he gets it right every time.
That’s Peter O’dell inserting his tool