Re: loose clutch = useless bike
check your cable. they're pretty cheap, and i've seen the clutch cable housing seperate from the inner spiral-wound metal part. what happens, is when you pull on the lever, the pressure on the cable housing causes the inner part to squeeze through the cable stops, and it basically makes your cable longer.
lemme try to make it clearer.
you have the plastic coated outer cable (housing) and the inner wire that attaches to the handlebar lever with the nub, and the cut end that attaches to the clutch arm at the motor.
inside the plastic coating is a spiral-wound metal tube, and the inner wire slides through this.
sometimes, the plastic covering gets compressed, causing the spiral wound part to stick out past the housing. the more you squeeze the lever, the more it compresses. the plastic housing still stops when it's jammed up against the adjusters, but the spiral wound inner housing doesn't.
if you take the cable off and see an inch or so of spiral windings, then you'll know what i'm typing about, and to fix it, go get a brake cable from the bike shop.
hope this made sense.