2020 YAMAHA YFM90R engine

4-11
4OFF
With the fuel cock lever in this position, fuel will not
flow. Always turn the fuel cock lever to this posi-
tion when the engine is not running. ON
With the fuel cock lever in this position, fuel flows
to the carburetor. Turn the fuel cock lever to this
position when starting the engine and riding.
1. Arrow mark positioned over “OFF”
1
1. Arrow mark positioned over “ON”
1
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4-12
4
RES
This indicates reserve. With the fuel cock lever in
this position, the fuel reserve is made available.
Turn the fuel cock lever to this position if you run
out of fuel while riding. When this occurs, refuel as
soon as possible and be sure to turn the fuel cock
lever back to “ON”!
EBU18852Starter (choke) “ ”Starting a cold engine requires a richer air-fuel
mixture. This mixture is controlled by the starter
(choke) system. To use the starter (choke) and enrich the air-fuel
ratio, move the starter (choke) lever in direction (a).
To decrease the starter (choke) or turn it off, move
the starter (choke) lever in direction (b).
TIPSee page 6-1 for engine starting instructions.
1. Arrow mark positioned over “RES”
1
1. Starter (choke) lever
1
(a) (b)
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5-1
5
EBU19203
PRE-OPERATION CHECKS
EBU19226Inspect your vehicle each time you use it to make sure the vehicle is in safe operating condition. Always
follow the inspection and maintenance procedures and schedules described in the Owner’s Manual.
WARNING
EWB00482Failure to inspect or maintain the vehicle properly increases the possibility of an accident or equip-
ment damage. Do not operate the vehicle if you find any problem. If a problem cannot be corrected
by the procedures provided in this manual, have the vehicle inspected by a Yamaha dealer. Before using this vehicle, check the following points:
ITEMROUTINE PAGE
Fuel • Check fuel level in fuel tank,
and add recommended fuel if neces-
sary.
• Check fuel line for leakage. Correct if necessary. 4-9, 5-3
Engine oil • Check oil level in engine, and add recommended oil to specified
level if necessary.
• Check ATV for oil leakage. Correct if necessary. 5-3, 8-10
Transmission • Check transmission case for leakage. 5-3, 8-14
Front brake • Check operation, and correct if necessary.
• Lubricate cable if necessary.
• Check lever free play, and adjust if necessary. 5-3, 8-21, 8-23
Rear brake • Check operation, and correct if necessary.
• Lubricate cable if necessary.
• Check lever free play, and adjust if necessary. 5-3, 8-21, 8-24
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5-3
5
EBU38000FuelMake sure there is sufficient gasoline in the tank
before starting off. Refuel if necessary. (See page
4-9.)EBU19561Engine oilMake sure that the engine oil is at the specified
level. Add oil as necessary. (See page 8-10.)EBU38541TransmissionMake sure there is no oil leaking from the trans-
mission case.EBU19653Front and rear brakesBrake levers
Check for correct free play in the brake levers. If
the free play is incorrect, adjust it. (See pages
8-23 and 8-24.)
 Check operation of the levers. They should
move smoothly and there should be a firm feel-
ing when the brake is applied. If not, have the
ATV checked by a Yamaha dealer. Brake operation
Test the brakes at slow speed after starting out to
make sure they are working properly. If the brakes
do not provide proper braking performance,
check the brake shoes for wear. (See page 8-21.)
EBU19762Throttle leverCheck the operation of the throttle lever. It must
open smoothly and spring back to the idle position
when released. Have a Yamaha dealer correct if
necessary.EBU19771Drive chainCheck the condition of the drive chain and check
the drive chain slack. Lubricate and adjust the
drive chain as necessary. (See page 8-25.)EBU19799TiresCheck tire pressure regularly to make sure it is at
the recommended specifications. Also check for
wear and damage.
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6-1
6
EBU19882
OPERATION
EBU19902Read the Owner’s Manual carefully before riding
the ATV. If there is a control or function you do not
understand, ask your Yamaha dealer.
WARNING
EWB00632Read the Owner’s Manual carefully to become
familiar with all controls in order to help pre-
vent any loss of control, which could cause an
accident or injury. EBU33822Starting a cold engineNOTICEECB00151See the “Engine break-in” section on page 6-4
prior to operating the engine for the first time. 1. Set the parking brake. (The engine can bestarted only when the rear brake lever is ap-
plied.)
2. Turn the fuel cock to “ON”. 3. Turn the key to “ON” and set the engine stop
switch to “ ”.
4. Shift the drive select lever into the neutral po- sition. (The neutral indicator light should
come on.)
5. Position the starter (choke) lever according to the ambient temperature.
Position (1):
Cold engine start with ambient temperature
below 5 °C (40 °F).
Position (2):
Cold engine start with ambient temperature
between 0 °C (30 °F) and 30 °C (90 °F).
Position (3):
Cold engine start with ambient temperature
above 25 °C (80 °F).
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6-2
6
Ambient temp./starter (choke) position
6. Release the throttle lever and start the engine by pushing the start switch.
TIPIf the engine fails to start, release the start
switch, then push it again. Pause a few seconds
before the next attempt. Each cranking should
be as short as possible to preserve battery en-
ergy. Do not crank the engine more than 10 sec-
onds on each attempt. 
If the engine fails to start using the start switch,
try using the kickstarter. (See page 4-7.)
7. If the engine is started with the starter (choke)
lever in position (1), move the lever to position
(2) to warm up the engine. If the engine is
started with the starter (choke) lever in posi-
tion (2), keep the lever in this position to warm
up the engine.
8. Continue warming up the engine until it idles smoothly, then return the starter (choke) lever
to position (3) before riding.TIPThe engine is warm when it responds quickly to
the throttle with the starter (choke) turned off. 9. Release the parking brake.NOTICEECB00164For maximum engine life, never accelerate
hard when the engine is cold!
1. Fully open
2. Half open
3. Closed
4. Starter (choke) lever
4
3
2
1
(1) (3)
(2)
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6
EBU20292Starting a warm engineFollow the same procedure as for starting a cold
engine, with the exception that the starter (choke)
is not required when the engine is warm. Instead,
start the engine with the throttle slightly open.EBU33831Operating the drive select lever and
driving in reverseNOTICEECB00171Before shifting, stop the ATV, otherwise the
transmission may be damaged. Shifting: Forward1. Bring the ATV to a complete stop.
2. Apply the rear brake lever.
3. Shift from neutral to forward by moving the drive select lever along the shift guide.TIPMake sure that the drive select lever is completely
shifted into position.
4. Open the throttle lever gradually.
Shifting: Reverse
WARNING
EWB00721Improper operation in reverse could make you
hit an obstacle or even a person behind you,
resulting in serious injury. When you shift into
reverse, make sure there are no people or ob-
stacles behind you. When it is safe to proceed,
go slowly. 1. Drive select lever
2. F (Forward)
3. N (Neutral)
4. R (Reverse)
FNR
234
1
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6-4
6
1. Bring the ATV to a complete stop.
2. Apply the rear brake lever.
3. Shift from neutral to reverse by moving the
drive select lever along the shift guide.
TIPWhen in reverse, the reverse indicator light should
come on. If the indicator light does not come on,
have a Yamaha dealer check the electrical circuit. 4. Check behind for people or obstacles, andthen release the rear brake lever. 5. Open the throttle lever gradually and continue
to watch to the rear while backing.
EBU20684Engine break-inThere is never a more important period in the life
of your engine than the first 320 km (200 mi) or 20
hours of operation. For this reason, you should fol-
low the engine break-in instructions carefully.
Since the engine is brand new, do not put an ex-
cessive load on it for the first 320 km (200 mi) or
20 hours. During this period the various parts in
the engine wear and polish themselves to the cor-
rect operating clearances. Avoid prolonged full-
throttle operation or any condition that might re-
sult in engine overheating.
0–160 km (0–100 mi) or 0–10 hours
Avoid prolonged operation above 1/2 throttle.
Vary the speed of the ATV regularly. Do not oper-
ate it at one set throttle position.
160–320 km (100–200 mi) or 10–20 hours
Avoid prolonged operation above 3/4 throttle. Rev
the engine freely, but do not use full throttle at any
time.
1. Drive select lever
2. F (Forward)
3. N (Neutral)
4. R (Reverse)
FNR
234
1
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