Yamaha KODIAK ULTRAMATIC YFM400FA Owner's Manual page 214

With the engine idling, shift the drive select le-
ver into low or high. Then release the parking
brake. Apply the throttle slowly and smoothly.
The centrifugal clutch will engage and you will
start to accelerate. If the throttle is applied too
abruptly, the front wheels may lift off the
ground resulting in a loss of directional con-
trol. Avoid higher speeds until you are thor-
oughly familiar with the operation of your ATV.
When slowing down or stopping, release the
throttle and apply the brakes smoothly and
evenly. Improper use of the brakes can cause
the tires to lose traction, reducing control and
increasing the possibility of an accident.
CAUTION:
Do not shift from low to high or vice versa
without coming to a complete stop. Damage
to the engine or drive train may occur.
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