1977 CB750

[lrc2089]

Hi, new to forum, new to CB's. I have a 1977 CB750 with 22k miles that I paid $500 for with hopes of building a brat/tracker/cafe out of. (Not sure yet, maybe a combo of all three.) Anyway, it ran decent when I bought it but a few months later I took it to a shop because I couldn't get it to run after cleaning carbs etc. and was told I had low compression on 3 of 4 pistons.

Here's my question: what's more cost efficient, new motor for $450+labor (not guarenteed), or rebuild mine? Can I get by with just new rings? Or would now be a good time to put a big bore kit in? I'm just looking for the cheapest way to get it running good. Thanks guys.

 

[dirtdigger]

Is this a K or F? What are the compression numbers? I would double check the compression yourself. If it ran fine before and got bad after the carb rebuild then I dont see why the compression is an issue unless it has been low the whole time and now you have compression and a carb issue to look into. Then do a leak down test and see if it is the valves or the rings before you tear into it. If you replace the rings and dont look into the head you will still have leaky valve/valves. The 750 gets expensive fast if you are looking at doing a rebuild the right way. If you are looking at going a big bore in the future you may as well do it now rather then having the motor apart twice. Once you start getting into wanting bigger motor/more performance then the $$$ adds up fast.