Have a 627cc vanguard twin ohv, engine surges real bad, new plugs, cleaned out gas tank, new lines, filter, cleaned carb. New fuel pump, tried to adjust carb, did no good, tried running with choke on, no good, engine starts on first crank over. Has a pop in both mufflers on fast rpms. Any one had this trouble?

Hi,
Very sensitive carb on that engine. It is dirt still in a low speed circuit, one or both of the two.
Peace,
Clarke