To see if your clutch basket is notched, you will have to remove the clutch plates. Undo the bolts holding the metal plate and pull out the clutch plates. Pay attention to the order (metal first or fiber first). Your basket will have machined notches that the fiber plates' tabs fit into. The load-bearing surface of these notches was smooth when new, so that the tabs could slide in and out on them. The clutch works by the plates moving slightly apart when you pull in the lever, so that the metal plates attached to the crankshaft slip inbetween the fiber plates attached to the transmission. When you release the clutch lever, the force of the springs push the plates together and they crankshaft power is passed on to the transmission. If there are notches worn into the sliding surfaces of the basket, the plates won't move smoothly and your clutch may not disengage fully, causing stalling. You can file the notches out, but they will come back even sooner, due to the larger clearance in the tab notches allowing the tabs to slam around. Kawi's don't have the strongest baskets, so you may have to put in a new basket. Hinson and PE Performance make replacements that are much tougher than stock.
A shop manual, (do a search for clymer's ) will be the best money you ever spent on your bike.