I'm new here, but not new to bringing old rice burners back to life. My ol' lady's dad gave me a 80 CB650C with 18K on the clock in really nice condition. I did the usual carb kit and air cutoff rebuild, but for some reason the damn 2 and 3 carbs kept overflowing, but it didn't start leaking until after I had the gas on for about 30 sec or so. Well, in order to get to the bottom of it I set up my carb test stand (c-clamp the bank to a board that's in the bench vice, set gas tank on ladder for fuel) and monitor the fuel level with clear hose. 1 and 4 stayed put, but 2 and 3 slowly kept going up, until fuel started coming out the main jet air orifice in the carb inlet. Turns out, upon investigating the float valve and seat, the inside of the seat where the little rubber tip seats against to shut off fuel was mildly corroded. Seeing as how they weren't the replaceable kind of valve seats, at least as far as I can tell, maybe with a press or something, I used one of the old needles, ground off the springy tip on the back end of it, stuffed a small red hose from a WD-40 nozzle into it, applied some valve grinding compound to the rubber tip, then went to town in the same fashion as you would if you were trying to resurface a valve seat. FYI, it worked like a charm. I've got the carbs on the test stand right now and the fuel level hasn't moved at all over an hour. Even though I didn't post much, I certainly used the search function alot. Thanks everyone. Now I gotta figure something out with that exhaust.
