Motorcycle carbs work great as long as you don't need an accelerator pump or power enrichment circuit. Motorcycles don't have vacuum advance, either. They use one carburator for one or two cylinders, generally, so the pulses from the intake action are strong enough that you don't need an accelerator pump and the vacuum is not steady enough for a vacuum operated power circuit. The carbs on my bike are sidedraft Keihins with a 38mm venturi. They are slide throttles with a main jet with a needle that opens the jet more as the throttle is opened. There is also a fixed idle jet with an air bleed. The throttles are all ganged to a big lever and there is a stop screw to adjust the idle speed and a choke linkage. It all works really well. I have been considering using three 44mm Mikunis on my 261 but they are getting kind of expensive.
