what is the ideal clearence for forged wiseco pistons(k810).just reringing my 810 and after hone i have about .004" is this too much should i have another cylinder bored out?

.0015 to .002". .004" is way loose.

Is the .004" at the bottom or top of the piston? They are tapered from top to bottom, widest at the bottom.

yea it`s at the bottom of the skirt. too lose ok

so a rebore with about .002" piston to cylinder clearance .is this average for forged pistons?

It depends on how the piston is made and what it is made from. my answer was for a Wiseco

are cast pistons set up tighter then forged?

Yes. However, Wiseco uses a high silicon 4032 material and can run almost as tight as a cast piston.

2618 material used by most others has to run with more clearance.

thanks for the info .i have been told for years that you have to run wisecos loose because they expand alot . just trying to seperate fact from urban legend. if anybody else has experiance with running to tight or to loose p/c post it please.

on my street motors i use the wiseco spec's on my race motors i go about .001 looser just because they don't get as much chance to warm up fully

kawi810 wrote:


The opposite is true with Wiseco.

APE Jay wrote:
Says the man who has probably sold and installed more Wiseco motorcycle kits than anyone else in this country.