The kickstart ooperates on the transmission, there's a ratchet mechanism that should engage when the lever moves off its rest. That's the likeliest place to look for the problem. If the bike can be ridden, then the clutch and gearbox are working. If you're just starting it and haven't ridden it, confirm that the clutch is engaged - the kickstart needs that to work. On an engine with no clutch the kickstarter will have very little resistance. Note that if it's working, clutch or not, it will turn the sprocket (and rear wheel if connected) if the gearbox is in gear.
