he does state "fresh rebuild" so I threw that out the window assuming they know what they are doing. but I could be wrong. I have the same exact carb that would backfire and spit when I would first fire the engine, it would also hiss and try to spit when I opened the secondaries. I put another smaller carb on without touching anything else, it never once backfired and ran tits. I jetted the 750 down, and it is running excellent, I still have not touched anything other than the carb.
without knowing where his timing is set , its all speculation
