Ok, I've got a litte 98 KE100(go ahead and laugh). anyway, it starts up on the first kick but after I shift it into gear it just revves up and doesn't drive the wheel at all. I realize this is probably something very simple but I'm pretty mechanically dumb. Any thoughts on what's causing this? Clutch? Transmission?

 

Clutch slippage most likely. However, the clutch cable may be adjusted incorrectly, not allowing the clutch to engage.

Hopefully it's the later one.

Good luck, and welcome to KF!