im going to replace my 19T front sprocket with a 21T. Anyone have any good tips or tricks dealing with the removal of the entire primary drive/clutch assembly? I have a haynes manual which i'll be using as a guide of course. The motor was rebuilt about 250 miles ago so do you think i could salvage the primary cover gasket? Will I need any specialty tools? How long does it take the average joe to do this job? Thanks!