ca77 piston ring thickness

[rick w]

Ok here goes, I know this has been addressed on this forum and I have tried to research older posts to try to figure this one out but still not sure on this one. I'm starting a rebuild on what I believe to be a 1964 305 [ca77] motor. when I finnally got the pistons out it appears to be the first time this motor has been apart. It has the original 60mm bore and pistons that look to be in good condition, however the motor was froze due to a small amount of rust on one cylinder wall I think honing will get it without any pitting, I hope. I will need new rings of course which leads me to my problem. I don't know if I need the thicker rings or the thinner ones. I tried to measure mine with a caliper and they seem to be about 1.52mm thick for the top rings. Any help with this would be great.

[Hoosier Tom]

I went out and measured some code -266- upper rings and got 1.78-1.80 mm. I measured some code -275- rings and got 1.44-1.46 mm. Sounds like you have the thinner ring pistons.

HT

[rick w]

Ok, thanks HT, this bike has a long history with me, but thats another story for another day when I can post pics. etc. just trying to get started on the motor for now. Does anyone have these thinner rings for sale? or should I just bite the bullet and get it bored and get pistons and matching ring set? Either way these parts seem to be getting harder to find and pricier every day.