Operation Manual

Page 16
Maintenance
Check flywheel and add ballbearingoil
Checking flywheel before riding to make sure there is not any
abnormal noise. If there is abnormal noise, turn up the scooter to let
its bottom upward and add 3 to 5 points ballbearingoil to the gaps
between flywheel and bearing, wait for a minute to let ballbearingoil
infiltrate into the flywheel. The user should add ballbearingoil every
month to keep it smooth and increase its life, even if there is not any
abnormal noise.