2017 YAMAHA YFM90 engine

4-9
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.
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
1. Maximum fuel level
2. Fuel tank filler tube
12
Recommended fuel:Regular unleaded gasoline only
For Europe: Regular unleaded gasoline only
with a research octane number of 95 or
higher
Fuel tank capacity: 6.6 L (1.74 US gal, 1.45 Imp.gal)
Fuel reserve amount: 0.9 L (0.24 US gal, 0.20 Imp.gal)
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4
immediately. If gasoline spills on your skin,
wash with soap and water. If gasoline spills on
your clothing, change your clothes.
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. Your Yamaha engine has been designed to use
regular unleaded gasoline with a research octane
number of 91 or higher (95 or higher for Europe). If
knocking (or pinging) occurs, use a gasoline of a
different brand. Use of unleaded fuel will extend
spark plug life and reduce maintenance costs.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. OFF
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.
1. Arrow mark positioned over “OFF”
1
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4-11
4ON
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. 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”!
EBU18851Starter (choke) “ ”Starting a cold engine requires a richer air-fuel
mixture, which is supplied by the starter (choke).
Move the starter (choke) in direction (a) to turn on
the starter (choke).
1. Arrow mark positioned over “ON”
1
1. Arrow mark positioned over “RES”
1
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4-12
4
Move the starter (choke) in direction (b) to turn off
the starter (choke).
See the “Starting a cold engine” section on page
6-1 for proper operation.
EBU34550SeatTo remove the seat
While pushing the rear of the seat down, pull the
seat lock lever upward and then pull up the seat at
the rear. To install the seat
Insert the projection on the front of the seat into
the seat holder and push down on the seat at the
rear. Make sure that the seat is securely fitted.1. Starter (choke) “ ”
1
(a) (b)
1. Seat
2. Seat lock lever
1
2
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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. 4-8, 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, 8-11
Transmission oil • Check ATV for oil leakage. Correct if necessary. 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, 8-22
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
EBU19542FuelMake sure that there is sufficient fuel in the tank.
(See page 4-8.)EBU19561Engine oilMake sure that the engine oil is at the specified
level. Add oil as necessary. (See page 8-11.)EBU34490Transmission oilMake sure that the transmission oil is at the spec-
ified level. Add oil as necessary. (See page 8-14.)EBU19653Front and rear brakesBrake levers
Check for correct free play in the brake levers. If
the free play is incorrect, adjust it. (See pages
8-22 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.)EBU19795TiresCheck 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. EBU33821Starting 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. Use the starter (choke) in reference to the fi- gure:
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
6Ambient temp./starter (choke) position
6. Completely close 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)
in position (1), the starter (choke) should be
returned to position (2) to warm up the en-
gine. If the engine is started with the starter
(choke) in position (2), keep the starter (choke)
in this position to warm up the engine.
8. Continue warming up the engine until it idles smoothly, then return the starter (choke) 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)
4
3
2
1
(1) (3)
(2)
UBD361E0.book Page 2 Monday, January 25, 2016 10:53 AM