The Mikunis do have an accelerator enrichment jet on them (it is one of the 3 things that can potentially give you grief, the other 2 are the secondary vac solenoid and the wax pellet auto choke). The enrichment jet pump is the square block on the side of the carb with the 2 fuel line barbs on it. Easy to see if it's working with the engine off - either hold the choke butterfly open or do it after the engine has warmed up. Look down the primary throat and give the throttle a quick turn - you should see a shot of fuel from a small nozzle halfway down the throat (you can hear it too if the pump is really good). No shot of fuel can mean 2 things - pump diaphragm is toast or you have a serious blockage in the jet.