Ok, so got down n' dirty with the 1979 400T the other day. It had the plug in left cyl with melted electrodes. Got it to fire up on carb cleaner and the right cyl sounds great but the left one smokes out the intake and has ZERO compression. At first I thought the usual, crapped out rings, blown piston or ring landings. . . the smoking out the intake makes me think about the intake valve. Maybe the valve seat fell out or the valve itself is melted or broken. Maybe the valve spring broke? Won't know until I pull the head. My biggest worry now is what everyone is saying about those vacuum operated carbs. I know they're 32mm, so what if I swapped out to an early model 400/450/500T carb set up like in my CB750K1. Should bolt right up and just have to jet accordingly right? Anyone else have experience with these carbs; and I would like to keep this bike as stock as possible. It is in wonderful shape other than the engine issue, only 9K on it.
