Flywheel

A flywheel is a
rotating disk used as a storage device for kinetic energy. Flywheels resist changes in
their rotational speed, which helps steady the rotation of the shaft when a fluctuating
torque is exerted on it by its power source such as a piston-based (reciprocating) engine,
or when the load placed on it is intermittent (such as a piston pump). However, it is bad when a driver need a fast engine response. Flywheel need to take
a lot of effort to make the wheel rotating and stops the engines revs increasing or slowly
down quickly. Lighted flywheel will cause the engine momentum reduced which mostly
noticeably on driving up the hill. Different weight of flywheel allow to get the free
revving capabilities and best torque.

But WHY? It means faster acceleration for both
positive and negative. By shortening the
time a rider waits as the engine speed matches the speed of the selected gear so they can
mesh without clashing.

Besides that, lighter flywheel is less likely to shear off the crank during hard
acceleration or deceleration. Few kilos of metal rotating at several thousand rpms is a
pretty fair gyroscope. When the scooter leans to turn, that little flywheel can exert
strong gyroscopic vectors which may affect the handling of the scooter, and may contribute
to the aforementioned crankshaft failure.

The disadvantages
include an increased risk of over-revving when miss shift a gear. Besides that, in order
to get the scooter rolling from dead stop will need to rev the engine a bit more. This is
because it has less rotational inertia to trade off. Plus, the spark will only last as
long as your battery, so this won't be practical for an endurance race. The newly-
lightened flywheel should be rebalanced to prevent vibration or failure.