Scooter's Belt Drive Fix
For BDL  and Ultima Beltdrives with one piece or two piece jackshafts

This amazing part will fix the “grind” associated with starting bikes that have a solid or very rigid belt drive actuation.

The engineered spring and ramped teeth help integrate the teeth before the unit locks in and turns.

Stop grinding your teeth—and the bike's jackshaft all while producing smoother and quieter starts

http://www.vabiker.net/2008/07/bullet-proof-bdl-belt-drive-starter-fix/
for an informative installation article
  written by Club Chopper member

Some Club Chopper Members have been successful installing the Fix on Ultima Belt Drives too
http://www.clubchopper.com/forums/showthread.php?t=60257&highlight=ultima+belt+drive
for more details
   

Pinion gear has 9 teeth