Skyeswom

I was going to use some Quicksilver Power Tune to clean out the carburetor; the first step is to remove the air filter. Which would be easy - if I knew where it was. I bought the bike used and have no manual. Where is the air filter, how do I remove it, and what tools do I need? Thanks!

thanks. Is that something I could do myself, or do I need to take it in?

When checking the oil using the window in the crank case, should the bike be up or on the kickstand?

No matter how warm the engine is, or how long it's run, it chugs and dies at low RPMs - stop lights, parking lots, etc. I have to rev it while holding in the clutch or the engine will quit. Spark plugs 2 & 3 are a little bit black; 1 & 4 are relatively clean. Could it be the jets in the carburetor? Any suggestions? I'd like to be able to ride without worrying about it quitting. . .