Mikuni VM carburetors are time-tested, reliable carburetors. They are infinitely tunable compared to the old Amals, and when set up properly, they work well on British iron. No more tickling Amals with resultant dripping gasoline. If you have ever ridden a motorcycle using the old type 276's, 289's and switch to Mikunis, carbs drooling gasoline will only be a memory.
I run 32mm Mikuni type VM's on the Vincent because the old 276/289's can be a fire hazard. In fact, the factory prototype Black Shadow caught fire and burned early in its its existence. Another plus for the 32mm VM's, is they are available with left or right side throttle adjusters.
Basic setup for a 998cc Vincent Black Shadow with 32mm type VM Mikuni's:
Engine: Standard bore, 7.3:1 compression ratio with stock MK-I camshafts. Standard exhaust with spiral baffle muffler.
Altitude 1200 feet above sea level.
Throttle slide: 3.0
Needle: 6DH2
Needle Clip in the middle position
Needle jet 159-P4
Pilot jet #35
Air Correction jet 1.0
Main jet: 300
This setup made my bike rideable. Adjustments may be necessary.