CP forged piston clearance

[TA63]

Homing out a set of 95 cylinders for some .030 CP forged pistons. Any recommendations on piston to wall clearance and ring gaps? 

[Armin]

Look for piston installation instructions on CP Carrillo's web site. It's all there.

Armin.

[Ohio HD]

You'll probably not find any info on the CP site for piston to cylinder clearance. They list how to size the rings based on the application and usage on the site.

If you're using CP Bullet pistons, they generally state 0.0025" in the spec sheet that should be with the new pistons. The clearance is generally based on how you want the motor to be, tighter or a little loose when breaking them in, or when running the motor.

I wouldn't go any less than 0.0025" and no more than 0.0035" as long as it's a street application and there are no added piston coatings to fill the bore clearance.

When in doubt, contact CP.


CP Carrillo


Added: Assuming you're using OEM or OEM style cylinders.

[SmokyOwl]

I was learning about the differences in forged pistons, and one downfall of them is that they require a slightly larger bore than cast pistons.  This is because they expand more than cast pistons.  Doesn't sound like a big deal I know, but this introduces piston slap on the cylinder walls as the bike is warming up, causing more wear on the cylinder walls.  Interesting stuff, found it on youtube.