Throttle Lever; Speed Limiters - Yamaha YFM90RA Owner's Manual

Throttle lever

Once the engine is running, movement of the throt-
tle lever will increase the engine speed.
Regulate the speed of the ATV by varying the
throttle position. Because the throttle is spring-
loaded, the ATV will decelerate, and the engine will
return to an idle any time the hand is removed from
the throttle lever.
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1. Throttle lever
Before starting the engine, check the throttle to be
sure it is operating smoothly. Make sure it returns
to the idle position as soon as the lever is released.

Speed limiters

Your ATV was delivered with two speed limiter
devices. A vehicle speed limiter adjusting screw
and a removable engine speed limiter plate.
Yamaha recommends that all beginning riders start
off with the vehicle speed limiter adjusting screw fully
turned in and the engine speed limiter plate installed
to limit the amount of speed available while they learn.
The vehicle speed limiter keeps the throttle from fully
opening, even when the throttle lever is pushed to the
maximum. The adjusting screw may be gradually
turned out as the beginner becomes more familiar with
operating the ATV. Parents should decide when to
adjust the ATV for more power as their youngster's
riding skills improve. Once the ATV rider can operate
with skill at the top speed permitted by adjusting the
vehicle speed limiter alone, the engine speed limiter
plate can be removed. Since removal of this limiter
will result in a significant increase in power, turn the
vehicle speed limiter adjusting screw completely back
in again; adjust it out in stages as done previously.
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