Bought a Downtown that was a left over last year, I think it is a 2011, don't remember. Anywho....it has had an intermittent problem. It would sometimes be really boggy. It would not kick into that sort of "second gear" the engine does when it gets past about 15 mph then takes off with a larger surge, it would just accelerate weakly. This would happen periodically and I tried taking off the gas cap to see if there was some vapor lock and reset the throttle setting with the standard procedure. I used some seafoam in the gas. But it would still happen on occasion and then seem to go away on its own for no reason only to reappear.
It occurred to me that since this was a leftover it probably sat for a year with gas in the tank, most likely with some Minnesota ethanol and perhaps there was some crud in the fuel system. I use techron concentrate in my cars with very good results and put in a healthy dose with a full tank of fuel. Within a very short time it ran like a beast and has displayed more power than its first few miles. I have not had the bogginess come back since I used it and suspect that the techron did the trick.
I read that this is one of the most aggressive and effective fuel additives money can buy and seem decent results in my car but it was like night and day after a couple days and 20 miles of it in the scooter. If you have any intermittent problems and suspect any crud in the fuel, give it a try. It seems to have cleared up a problem in mine that sea foam would not.