Recent content by Mars

I finally got up the courage to work on the engine. Turns out it was a bent exhaust valve. It isn't mangled, but the stem is bent enough that it wasn't seating properly. I'm going to replace it with one I pulled from a 1981 CB750C. While I have the engine out I'm going to clean up what I...

I got mine out with compressed air. Just be careful to keep it aimed at the floor and have something soft like a wadded up towel to catch it.

Have you gotten a chance to do the valve adjustment yet? I checked clearances on mine and confirmed I don't have a stuck valve, so I think I the piston rings on one of my cylinders is shot. I bought a gasket kit, which maybe I should have waited to do, and will be pulling the engine at some point.

Was this bike running before? Was it sitting a long time? There are more experienced people who might be able to help you, but I just had this issue with a 1979 (so maybe not exactly same carbs?). I got my bike firing but if I let the throttle down below about 3K it would die. My issue, and...

Cylinders 1-3 look fine, it is #4 that worries me at 30 psi when tested dry.. and ~200 when wet, but I may have had too much oil in the cylinder to get a proper reading.

That's possible. It definitely was not "very very little". I'll be real happy if I can get away with just a valve adjustment! I will try to check clearances tomorrow. Thanks for the advice grepper and dirtdigger

I guess I didn't mention it here, but I did a wet compression test which sent it from 30 psi up to 205 which made me think it is the rings, but I will be happy if I'm wrong and really don't know much. Does that change what you think? Either way it sounds like I will have to pull the engine. I...

Thanks Dave. I will be changing tires and chain before riding. Everyone here recommends the course, I've already signed up (paid) and it is a convenient way to get the license.

Thanks for the reply grepper. I appreciate the advice. Something else that is going on is that I have super low compression on just the #4 cylinder. The engine seems to run really well once it's warmed up but until then will hesitate or stall at idle and if I quickly roll on the throttle it...

Hello all, I'm in the process of getting a 1979 CB750L back up and running after something it sat for about 20 years in a shed. I've got it running pretty well actually but when syncing the carbs notices #4 cylinder a little wonky. Have driven it just a couple miles. Dry compression test...

Man, am I jealous. I just got one and it is a horror show compared to yours. If the previous owner didn't burn valves or anything like that you might be in really great shape already.

I thought I might as well join so I can learn some things about this bike. I'm very new to motorcycles in general and taking a safety course at the end of the month. I'm throwing a lot in here and don't expect anyone to answer all of it, but if anyone has any comments about anything it might...