Greg CB750
CB750 Member
I have a 1991 CB 750 Nighthawk with 11K miles. Once warmed up, the bike runs very strong, although it hesitates a little bit when hitting throttle fast from idle. The problem is that when I start it cold with full choke on, it will only run on two cylinders (first and second from the right). Also, even with full choke on, the idle sits at just about 1k rpm (shouldn't it be more like 2 or 3K?). I am unable to advance the throttle without the engine dying unless I let it warm up on those two cylinders for a few minutes. Even then, it takes a lot of feathering the throttle to get it to reach higher rpm without stalling. How do I know it only runs on two most outer right cylinders? After running it for a few minutes with choke on, the exhaust pipes on the left side are completely cold and so is the head while the right side is hot. I am thinking the choke or air/fuel mixture must be off, but I am not sure what I can adjust. Would you recommend carb cleaning/rebuild service?