improper idle settings or brake settings?
along with the 4n1 clutch & new bearings i would get two sets of bearings if you can, and if you clutch bearings were fried theres a good chance the clutch nut may now be out of round if the bearings seam a little tight going on or comming off the the clutch nut get a new one or you just blow your bearings again after a few runs.
good luck