Topic: CB500 big bore?

[kayaker43]

Hard to tell from the pics but the pistons are either flat, or nearly flat? Also the valve pockets look odd,... too large a radius compared to a typical valve, maybe they were enlarged by someone. Its also odd that any aftermarket 810 piston kit would say Honda on it

[jwcsdc]

I have my manual trust me, Im looking forward to the challenge,lol. I just hope I can get all the parts needed to get it back together. I took it apart cause it started to smoke, I hate that so jumped on it. Bad part was we were 350 miles from the house when it started this. Good ol uhaul got us home and next day jumped on it. Im going to pick up the cylinders tues from the bike shop. Ill get a few pics and post them. Now that I have a idea of what im dealing with Im going to try to keep the locals out of it. I could be wrong but all the guys at the import bike shops around here arent as creative as I would like them to be. If its not factory seems like they are against it. Does anyone know where I could get rings for these pistons? Maybe a over sized if needed? Thanks to all of you that have responded so far

[mlinder]

4th oversize for the cb750 was 62.
I don't know of anyone who makes 63mm pistons for these.
You may have to step up to the 811/12 kit, 64mm, or I dunno. Someone's still gotta make the 812 kit pistons and rings. I'm guessing 1mm over can be done on your sleeves.

[paulages]

try http://www.hastingsmfg.com/. if you haven't tossed the old rings, you can measure them for reference. they won't have them as a kit, but will likely have the right sizes if you can give them the specs.

[jwcsdc]

Thanks, I havent tossed anything yet. Im going to get the cylinders tomorrow and will post pics and numbers

[jwcsdc]

cylinders are 500 also, there is just sleeves sticking out the bottom. I didnt see a casting number on the head. Just a 3 didgit that looked like a shift code. I can take pics if anyone needs them.