Moped Army

I finally got my Bat running. (thanks to those who offered advice by the way) The problem is that when I took it out on the road it was really slow even at full throttle. I mean slower than I can walk, probably less than 5 mph. Now, I still have to get the mixture on the engine right and take of some other stuff, but I was thinking that it was either the clutch slipping or possibly lack of compression. Anyways, I would appreciate any input on the matter, ecspecially about fixing the clutch because my knowledge of them is very minimal.

Thanks,
Info_kill