is the pressure plate centered correctly (the part with the 5 bolts and springs)
are the bolts (with the springs) correctly torqued?
is the rod from the left side of engine that passes thru the basket to release the pressure plate correctly installed?
is the clutch adjusted correctly?
did you soak the clutch disks (frictions) in clean motorycycle oil before installing? (note, I said motorcycle oil, or other oil that's safe for our wet clutches)
did you offset the last plate one tab? (most of the tabs line up, last plate is offset 1 tab)
last but not least, are the rear splines in good order? (if they are stripped, you aint going anywhere). note: REAR splines, the ones at the rearmost bevel gear where the driveshaft connects to the rear final drive