YAMAHA YFM90 2017 Service Manual

4-10
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
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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4
EBU18995Adjusting the front shock absorber as-
sembliesThe spring preload can be adjusted to suit the rid-
er’s weight and the riding conditions.
WARNING
EWB00401Always adjust the shock absorber assemblies
on the left and right side to the same setting.
Uneven adjustment can cause poor handling
and loss of stability, which could lead to an ac-
cident.
NOTICEECB01091Never turn the adjusting mechanism beyond
the minimum and maximum settings. Adjust the spring preload as follows.
Turn the spring preload adjusting ring in direction
(a) to increase the spring preload and thereby
harden the suspension, and in direction (b) to de-
crease the spring preload and thereby soften the
suspension.
Align the appropriate notch in the adjusting ring
with the position indicator on the shock absorber.
1. Projection
2. Seat holder
12
1. Spring preload adjusting ring
2. Position indicator
123 45
2
1(a)
(b)
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4
TIPA special wrench can be obtained at a Yamaha
dealer to make this adjustment.
EBU19024Adjusting the rear shock absorber as-
semblyThe spring preload can be adjusted to suit the rid-
er’s weight and the riding conditions.NOTICEECB01091Never turn the adjusting mechanism beyond
the minimum and maximum settings. Adjust the spring preload as follows.
Turn the spring preload adjusting ring in direction
(a) to increase the spring preload and thereby
harden the suspension, and in direction (b) to de-
crease the spring preload and thereby soften the
suspension.
1. Special wrenchSpring preload setting:Minimum (soft):1
Standard: 3
Maximum (hard): 5
1
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4
TIPA special wrench can be obtained at a Yamaha
dealer to make this adjustment. 1. Spring preload adjusting ring
2. Position indicator
123 45
2
1
(a)
(b)
1. Special wrenchSpring preload setting:
Minimum (soft):1
Standard: 2
Maximum (hard): 5
1
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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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Throttle lever• Make sure that operation is smooth. Lubricate cable and lever
housing if necessary.
• Check lever free play, and adjust if necessary. 5-3, 8-20
Control cables • Make sure that operation is smooth. Lubricate if necessary. 8-28
Drive chain • Check chain slack, and adjust if necessary.
• Check chain condition. Lubricate if necessary. 5-3, 8-25, 8-27
Wheels and tires • Check wheel condition, and replace if damaged.
• Check tire condition and tread depth. Replace if necessary.
• Check air pressure. Correct if necessary. 5-3
Brake levers • Make sure that operation is smooth. Lubricate lever pivoting points
if necessary. 8-29
Chassis fasteners • Make sure that all nuts, bolts and screws are properly tightened. 5-6
Instruments and switches • Check operation, and correct if necessary. 5-6
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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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5Tire pressure
Use the low-pressure tire gauge to check and ad-
just tire pressures when the tires are cold. Tire
pressures must be equal on both sides.
WARNING! Operation of this vehicle with im- proper tire pressure may cause severe injury or
death from loss of control or rollover. Tire
pressure below the minimum specified could
also cause the tire to dislodge from the rim un-
der severe riding conditions.
[EWB02542]
Set tire
pressures to the following specifications:
The low-pressure tire gauge is included as stan-
dard equipment. Make two measurements of the
tire pressure and use the second reading. Dust or
dirt in the gauge could cause the first reading to be
incorrect.Recommended tire pressure:
Front24.0 kPa (0.240 kgf/cm², 3.5 psi)
Rear 24.0 kPa (0.240 kgf/cm², 3.5 psi)
Minimum tire pressure: Front20.7 kPa (0.207 kgf/cm², 3.0 psi)
Rear 20.7 kPa (0.207 kgf/cm², 3.0 psi)
Maximum tire seating pressure: Front250 kPa (2.5 kgf/cm², 36 psi)
Rear 250 kPa (2.5 kgf/cm², 36 psi)
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