Topic: 550 oversize pistons

[zoeyk9]

I have just bought two CB550s and want to make one out of all the parts. But the "best" engine is sadly lacking compression, I have 100psi on one cyl and 85 on the other three. I did a leak-down test and piston blow by is the cause.
After looking around on the net I can't seem to find any low cost oversize piston/ring sets. There is a guy selling a 555 conversion set for about $129.00 but they are for a 500 and are almost the same size as the standard 550. I would think a rebore is the way to go for me. Any leads or help would be most welcome.

Zoeyk9

[bwaller]

Honda offers oversize pistons for these.

On occasion there are some 61mm pistons for sale by the same outfit that offers the 555cc kit. This bore works out to 592cc. These are Henry Abe pistons and use old one piece oil rings, which are garbage. The oil ring groove can be enlarged to use a three piece std CB750 oil ring and as a matter of fact the two compression rings can be substituted for the 750 items as well. A better choice for quality rings.

Another option is to use the 61mm CB750 piston and machine the crown and skirt to fit. There is write-up for this mod somewhere here or pm me and I can send it to you.

This is as far as you can bore the stock 550 liner. A little porting, add a cam and it's a whole other engine.

[bryanj]

The 555 is 2nd oversize for the 550