Currently working on a 1992 Yamaha Big Bear 350 that idles perfect but cuts out with any kind of throttle. We replaced carburetor and head to carburetor boot.
Put in a new spark plug, the old one was black as hell, unsure if it was caused by old carburetor or current misfire. This problem similar to the rev limiter you see on newer models when
differential is locked or in reverse. I don't think this machine has that feature but I could be wrong? I suspect an ignition component is breaking down but at the moment I don't have access to a wiring diagram or workshop manual but I'm working on that. Are the e-manuals any good?