if i understand this correctly you say if you have too much of an air leak you loose your vacum? it would have to be a pretty big air leak i would think. i know when on my old 500 or even my wifes 250 if you run it w/out the air filter or cover it does act a little boggy.try it and let us know.

 

Just for the heck of it you might want to try taking air filter cover off and remove the piece of grey foam that it slides through under the gas tank.Put your air filter and cover back on and give it a try. For some reason that foam gave me problems and when I removed it ...FIXED!!

Worth a try!!

 

I pulled out the gasket around the lid to the air box and flipped it over. It did run better, but still bogged down. I'll know more once I can get it out and let it run. But there was improvement.