2020 YAMAHA YFM90R engine

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EBU33802Speed limiterYour ATV was delivered with two speed limiter de-
vices. 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 in-
stalled 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 plate will result in
a significant increase in power, turn the vehicle
speed limiter adjusting screw completely back in
again and adjust it out in stages as done previous-
ly.Vehicle speed limiter
1. Loosen the locknut.
2. To increase the maximum engine power available and the maximum speed of the ATV,
turn the adjusting screw in direction (a). To
decrease the maximum engine power avail-
able and the maximum speed of the ATV, turn
the adjusting screw in direction (b). Do not
turn the adjusting screw out more than 14.5
mm (0.57 in) or the throttle cable could be
damaged. Always make sure the throttle lever
free play is adjusted to 1.5–4.0 mm (0.06–
0.16 in). (See page 8-20.) WARNING! Im-
proper adjustment of the speed limiter and
throttle could cause throttle cable damage
or improper throttle operation. You could
lose control, resulting in an accident.
[EWB00242]
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3. Tighten the locknut.
Engine speed limiter plate
When the engine speed limiter plate is installed,
engine speed is limited to 4900 r/min. When this
plate is removed, top engine speed (8500 r/min) is
available.
Remove the plate as follows. 1. Remove the seat. (See page 4-13.)
2. Loosen the screws, and then remove the plate as shown. 3. Tighten the screws.
4. Install the seat.
TIPStore the engine speed limiter plate with the Own-
er’s Manual so that it is readily available whenever
you want to reduce top engine speed.
1. Locknut
2. Adjusting screw
3. No more than 14.5 mm (0.57 in)
1
3
2
(b)
(a)
1. Screw
2. Engine speed limiter plate
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EBU18393Front brake leverThe front brake lever is located on the right han-
dlebar. To apply the front brake, pull the brake le-
ver toward the handlebar grip.
EBU18403Rear brake leverThe rear brake lever is located on the left handle-
bar. To apply the rear brake, pull the brake lever
toward the handlebar grip.EBU18462Parking brakeUse the parking brake before starting the engine
or after parking the ATV, especially on a slope. Ap-
ply the rear brake lever and push down the lock
plate to apply the parking brake. Squeeze the rear
brake lever to release the parking brake.
1. Front brake lever
1
1. Rear brake lever
1
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WARNING
EWB00221Always set the parking brake before starting
the engine. The ATV could start moving un-
expectedly if the parking brake is not ap-
plied. This could cause loss of control or a
collision.
 Always be sure you have released the park-
ing brake before you begin to ride. The brake
could overheat if you ride the ATV without re-
leasing the parking brake. You could lose braking performance which could cause an
accident. You could also wear out the brakes
prematurely.
EBU18583Drive select leverThe drive select lever is used to shift the transmis-
sion into the forward, neutral and reverse posi-
tions. See page 6-3 for drive select lever
operation.
1. Parking brake lock plate
1
1. Drive select lever
1
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EBU33893KickstarterUse the kickstarter to start the engine when the
battery voltage is low. 1. Remove the seat (page 4-13), and then re- move the kickstarter lever.
2. Remove the kickstarter lever cap. 3. Install the kickstarter lever.
4. Move the kickstarter lever down lightly with
your foot until the gears engage, and then
push it down smoothly but forcefully.1. Kickstarter lever
1
1. Kickstarter lever cap
1
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5. When the engine has started, remove the kickstarter lever and store it under the seat.
6. Install the kickstarter lever cap and the seat.
NOTICEECB02300Do not use the kickstarter if the battery is not
installed or if the battery leads are not connect-
ed.
EBU37980Fuel tank capRemove the fuel tank cap by turning it counter-
clockwise.
WARNING
EWB02522Gasoline and gasoline vapors are extremely
flammable. To avoid fires and explosions and
to reduce the risk of injury when refueling, fol-
low these instructions. 1. Before refueling, turn off the engine and be sure that no one is sitting on the vehicle. Nev-
er refuel while smoking, or while in the vicinity
1. Fold out.
2. Push down.
1
2
1. Fuel tank cap
1
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4of sparks, open flames, or other sources of
ignition such as the pilot lights of water heat-
ers and clothes dryers.
2. Do not overfill the fuel tank. When refueling, be sure to insert the pump nozzle into the fuel
tank filler hole. Stop filling when the fuel
reaches the bottom of the filler tube. Because
fuel expands when it heats up, heat from the
engine or the sun can cause fuel to spill out of
the fuel tank. 3. Wipe up any spilled fuel immediately.
NOTICE: Immediately wipe off spilled fuel
with a clean, dry, soft cloth, since fuel may
deteriorate painted surfaces or plastic
parts.
[ECB00982]
4. Turn the fuel tank cap fully clockwise to make sure it is securely closed.EBU38650FuelMake sure there is sufficient gasoline in the tank
before starting off. Refuel if necessary.
WARNING
EWB02532Gasoline is poisonous and can cause injury or
death. Handle gasoline with care. Never siphon
gasoline by mouth. If you should swallow some
gasoline or inhale a lot of gasoline vapor, or get
some gasoline in your eyes, see your doctor
immediately. If gasoline spills on your skin,
wash with soap and water. If gasoline spills on
your clothing, change your clothes.
1. Maximum fuel level
2. Fuel tank filler tube
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TIPConfirm the gasoline pump nozzle has the same
fuel identification mark.
About the recommended fuel
This model’s engine has been designed to use
regular unleaded gasoline. The research octane
number should be 95 or higher. If knocking or
pinging occurs, try a gasoline of a different brand
or higher octane.TIPGasoline containing ethanol can be used if the
ethanol content does not exceed 10% (E10). Gas-
oline containing methanol is not recommended
because it can cause damage to the fuel system
or vehicle performance problems. NOTICEECB00071Use only unleaded gasoline. The use of leaded
gasoline will cause severe damage to internal
engine parts, such as the valves and piston
rings, as well as to the exhaust system. EBU18821Fuel cockThe fuel cock supplies fuel from the tank to the
carburetor while also filtering it.
The fuel cock lever positions are explained as fol-
lows and shown in the illustrations.
Recommended fuel:
Regular unleaded gasoline only
Fuel tank capacity: 6.6 L (1.7 US gal, 1.5 Imp.gal)
Fuel reserve amount: 0.9 L (0.24 US gal, 0.20 Imp.gal)
1. EN228 fuel identification mark
1
E5
E10
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