CB 72 rebore

[perry400]

Hi
Have had the cylinders rebored on my CB 72, for 0.5mm oversize Pistons.
The Pistons feel tight in the bore, they move by hand but feel a little tight, the workshop manual states cylinder to piston clearance of 0.1mm (0.0039 in). Is this normal on fresh bore.
Thanks for any help in advance.

[Tim Miller]

Hi
Have had the cylinders rebored on my CB 72, for 0.5mm oversize Pistons.
The Pistons feel tight in the bore, they move by hand but feel a little tight, the workshop manual states cylinder to piston clearance of 0.1mm (0.0039 in). Is this normal on fresh bore.
Thanks for any help in advance.

I bore and hone my own cylinders and go with .002" clearance measuring at bottom of piston skirt when using stock ART piston. I would not recommend more than .0025". You might hear some piston slap noise with .0039".

Tim

[perry400]

Hi
Have had the cylinders rebored on my CB 72, for 0.5mm oversize Pistons.
The Pistons feel tight in the bore, they move by hand but feel a little tight, the workshop manual states cylinder to piston clearance of 0.1mm (0.0039 in). Is this normal on fresh bore.
Thanks for any help in advance.

I bore and hone my own cylinders and go with .002" clearance measuring at bottom of piston skirt when using stock ART piston. I would not recommend more than .0025". You might hear some piston slap noise with .0039"

Hi Tim Thanks for the advice.
Is it normal for the piston and rings to feel tight in the cylinder on brand new bore and piston rings?, When put back together I can move the piston up and down the cylinder with the rings installed, but it feels tight, is this normal? im used to building two stroke engines with much larger cylinder clearance.

[perry400]

I have measured the newly honed bores and both are 54.4mm, does this sound correct for 0.5mm oversize pistons?