from the description it sounds like its going rich on the tail end of the progression cct, at the cross over point when the main cct kicks in.
The air jet size may benefit from going up a couple of sizes to 180.[but that really only influences the mixture at high revs on the main cct] Whats the engine capacity again? 1200 or 1400? Also does the Pilot jet = idle jet?

And lastly whats the choke tube and Aux vent sizes?

cheers
benny