Remove engine.
Remove Flywheel cover
Remove flywheel-flywheel puller required
Remove stock woodruff key from crankshaft
Wipe end of crankshaft clean
Apply a small amount of grease to crankshaft end and keyway
Install the Advance key with the offset on the left side (towards exhaust)
Re-install flywheel, lining up the keyway in the flywheel with the advance key.
Press flywheel on as far as possible by hand, it may be tight going on to the Advance Key
Install flywheel nut and tighten
Re-install flywheel cover
Re-install engine onto scooter

*Note: Advance key replaces the stock woodruff key.