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Mechano .... on the accelerator pump.
Unlike the Delorto carbies on my Ducati, the Keihen do not have an accelerometer pump.
The SM/BA carbies are in fact a little "slow". Let me explain.
Most carbies, you twist the grip, the cable pulls up the slide, the engine gets fuel/air. Our Keihen jobs, you twist the grip, the cable open a butterfly, the butterfly allows air in, creates a vaccuum above the slide, pulls the slide up and the engine gets fuel/air.
Having sadi that, they are reliable and extremely common. The Harleys use 'em. In fact MANY brands of bike use them.
I have to keep telling myself, "Michael, you bought a CRUISER!" It's just that it gallops so hard.... you just want MORE!!!



Accelerator pump is a lot common expecially on big displacement engines. And Keihin CV come in both verions, with/without accelerator pump.

The pup is a system that spry a bit of carburant directly into venturi when the throttle is open fastly.
No spry if you open it progressively.

Harleys and lot of engines need it because the lean condition of a fast opening of the throttle body causes the so called carb farts, and engine stumbling.

Also some small displacement engines need an accelerator pump, there's examples of small 24mm carbs with accelerator pump.

I think the needing of an accelerator pump is due to intake system shape and volume.
If the distance between carbs and intake valves is short and overall intake volume is not big there's no need of accelerator pump.
If you have a big carburator with a big intake manifold like the Y shaped on Harley's, Vulcan's, Yamaha's Wildstar, you need an AP. Because when you fastly wide open throttle the time the engine sucks carburant up from main jet/emulsion tube it gets lot of air causing a lean condition.

Maybe our bike has rare carb farts and/or backfiring due to short and low volume manifold and Triumph decided accelerator pump version of CV is not necessary.

Also my Kawasaki ZRX1200 with the same CVK36 hasn't accelerator pump, but some Suzuki SACS need it. Bandit 1200 SACS engine used some particular Mikuni's with 3 fuel circuits with pilot jet, needle, middle jet and main/upper jet.
The 1990 GSXR 1100 used accelerator pump.