Originally Posted by ...ladies
^^ Ya, the rubber seal may be creating a vacum -sp- in your tank and not letting the gas flow freely. This happended with one of my friends come to think of it. Although his was more effected, he comepletely sealed it up. If that doesn't work there are lots of posts on spark plugs in here if you think thats really it. Odds are its something little.
I'll try it without the cap, we'll see what happens. I think I'll probably replace the stock plug wire. I've already gotten a better plug. Beyond that and possibly adjusting the needle setting, I dunno what else to do.