When throttling for takeoff I've been getting a stumble around 1700 RPM.
When the throttle is pushed forward normally (smooth / slow) the engine 'stumbles' for a couple seconds and then revs up normally. The engine smooths out around 1800 RPM.
If the throttle is pushed forward quickly I can almost stall the engine.
I've heard of this behaviour on the Strombergs but not Marvel Scheblers.
Is it possible the accelerator pump is injecting too much fuel? Any ideas?