'66 CB77 standard 60mm pistons

Steveo123 · Post by **Steveo123** » Thu Jul 06, 2017 4:51 pm

Hello everyone! First time posting, and recent forum member. I just picked up a 1966 CB77 (as per the sticker on the harness). Unfortunately, it's missing standard (60mm) pistons!

I realize these are available new, primarily in kits with the rings, pins and clips, and may very well go that way; however, I wanted to post to see if anyone has some used but serviceable pistons they'd like to part at a reasonable price. I'm in South Carolina, USA.

I'm really enjoying learning about these classics!

Thanks in advance, guys!

Hoosier Tom · Post by **Hoosier Tom** » Thu Jul 06, 2017 6:08 pm

Welcome! Did you have your cylinders measured to make sure you don't need an overbore? I ask because we get new people on here with very little to no mechanical knowledge from time to time.

HT

Steveo123 · Post by **Steveo123** » Thu Jul 06, 2017 7:01 pm

Hey there! Thanks for your reply! I did measure the cylinder sleeves with the right tool/method, so I am certain I need std. 60 mm pistons. While I certainly am not familiar with these motorcycles, I'm pretty knowledgeable about mechanicals generally. I just recently rebuilt my VW Type 3 engine from the bottom up !☺️ Fortunately I don't think I'll need to do the same with the CB77, but it does certainly need pistons! 😂 Anyway, again thanks, and any ideas for some reasonably priced pistons would be great!

rrietman · Post by **rrietman** » Thu Jul 06, 2017 11:34 pm

Steve; for the same $ you can certainly get an over bore piston. boring is about $40 per hole and you then have a fresh start with no taper and out of round, which is quite likely what you have now even if it measures std.
Good luck
Randy

Steveo123 · Post by **Steveo123** » Fri Jul 07, 2017 6:13 am

Thanks Randy. The whole "steel cylinder sleeve in the aluminum case" thing has me a little confused. When you mention boring the holes for larger pistons, are you referring to boring the sleeves, or the case? If the latter, wouldn't I then need new oversize sleeves as well?

I guess the more succinct way of getting to the heart of the matter is to ask: can I bore out the existing sleeves by, say, .25 mm, and then get .25 mm oversize pistons?

Thanks, and I apologize in advance for my ignorance!

Stephen

rrietman · Post by **rrietman** » Fri Jul 07, 2017 9:54 am

you would bore the steel sleeves. first , get your pistons. then take everything to the machinist so he can make the cut allowing for correct clearance between piston/cyl.
Good luck
Randy

Steveo123 · Post by **Steveo123** » Fri Jul 07, 2017 9:56 am

Excellent; thanks Randy! And have a great weekend.