my 81 GS450 is having some ignition problems, it would seem. It's been sitting for over a month now since San Diego has been really rainy and I haven't replaced the flat (and very worn) rear tire yet. So, I start it every few days to keep everything running. Lately, it's been fouling really bad out the left cylinder. It won't fire until the revs are about 5k, and even then I can see big plumes of fuel smoke as it fouls every few RPM. Is this a result of sitting? Will it clear up after the bike has been ridden regularly again?