YAMAHA YFM90R 2021 Owners Manual

9-32
9
3. Disconnect the negative battery lead first,
then the positive battery lead by removing
their bolt. NOTICE: When removing the bat-
tery, the main switch must be off, and the
negative lead must be disconnected be-
fore the positive lead.
[ECB01002]
4. Pull the battery out of its compartment.
NOTICEECB00622Never attempt to open the battery or remove
the battery cell seals, as this would permanent-
ly damage the battery. To charge the battery
 Confirm the recommended charging rate as
specified on the battery itself.
 Select a suitable charger and follow the manu-
facturer’s instructions.NOTICEECB00933To charge a VRLA (valve-regulated lead-acid)
battery, a special battery charger is required.
Using a conventional battery charger will dam-
age the battery. To store the battery
If the ATV will not be used for more than one
month, remove the battery, fully charge it, and
then place it in a cool, dry place.
 If the battery will be stored for more than two
months, check it at least once a month and fully
charge it if necessary.
1. Positive battery lead (red)
2. Negative battery lead (black)
3. Battery
4. Battery band
3
4
2
1
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9
NOTICEECB00942Always keep the battery charged. Storing the
battery in a discharged state for an extended
period of time will cause permanent battery
damage.
 Do not store the battery in an excessively
cold or warm place [below freezing or above
30 °C (90 °F)]. To install the battery
1. Place the battery in its compartment.
2. Connect the positive battery lead first, then connect the negative battery lead by installing
their bolt. NOTICE: When installing the bat-
tery, the main switch must be off, and the
positive lead must be connected before
the negative lead.
[ECB01111]
3. Hook the battery band.
4. Install the seat. (See page 5-13.)TIP Make sure the positive and negative battery
leads are installed as shown.
 Fully charge the battery before installing it. 1. Positive battery lead (red)
2. Negative battery lead (black)
2
1
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9
EBU25248Replacing the fuseIf an electrical problem is suspected, check the
fuse and replace it if necessary as follows.NOTICEECB00641To prevent accidental short-circuiting, turn off
the main switch when checking or replacing a
fuse. 1. Turn off all electrical systems. (See page 5-1.)
2. Remove the seat. (See page 5-13.)3. Remove the blown fuse, and then install a
new fuse of the specified amperage.
WARNING! Always use a fuse of the spec- ified rating, and never use a substitute ob-
ject in place of the proper fuse. An
improper fuse or a substitute object can
cause damage to the electrical system,
which could lead to a fire.
[EWB02173]
4. Turn on the main switch and start the engine.
5. Install the seat.
6. If the fuse immediately blows again, have a Yamaha dealer check the vehicle.EBU34030Removing a wheel1. Place the ATV on a level surface.
2. Loosen the wheel bolts.
1. Fuse
2. Spare fuse
2 1
Specified fuseW
7.5 A
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9-35
93. Elevate the ATV and place a suitable stand
under the frame.
4. Remove the bolts from the wheel.
5. Remove the wheel.
EBU34042Installing a wheel1. Install the wheel with the arrow mark pointing in the forward rotating direction of the wheel,
and then install the wheel bolts. 2. Lower the ATV to the ground.
3. Tighten the wheel bolts to the specified
torques.1. Wheel bolt
1
1
1. Arrow mark
2. Forward rotating direction
3. Wheel boltTightening torquesWFront wheel boltW45 N

9-36
9
EBU25721TroubleshootingAlthough Yamaha ATVs receive a thorough in-
spection before shipment from the factory, trouble
may occur during operation. Any problem in the
fuel, compression, or ignition systems, for exam-
ple, can cause poor starting and loss of power.
The following troubleshooting chart represents a
quick and easy procedure for checking these vital
systems yourself. However, should your ATV re-
quire any repair, take it to a Yamaha dealer, whose
skilled technicians have the necessary tools, ex-
perience, and know-how to service the ATV prop-
erly.
Use only genuine Yamaha replacement parts. Im-
itation parts may look like Yamaha parts, but they
are often inferior, have a shorter service life and
can lead to expensive repair bills.
WARNING
EWB02281Do not smoke when checking the fuel system.
Fuel can ignite or explode, causing severe inju-
ry or property damage. Make sure there are no
open flames or sparks in the area, including pi-
lot lights from water heaters or furnaces. UBD365E0.book Page 36 Monday, January 27, 2020 9:05 AM

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9
EBU25754Troubleshooting chart
Check the fuel level in
the fuel tank.1. Fuel
There is enough fuel.There is no fuel.
Check the battery.
Supply fuel.
The engine does not start.
Check the battery.
The engine does not start.
Check the ignition.
Operate the electric starter.4. Compression
There is compression.
There is no compression.
The engine does not start. Have a Yamaha dealer check the ATV.Have a Yamaha dealer check the ATV.
Remove the spark plug
and check the electrodes.3. Ignition
Wipe off with a dry cloth and correct the
spark plug gap, or replace the spark plug. Have a Yamaha dealer check the ATV.
The engine does not start.
Check the compression.
Operate the electric starter.2. Battery
The engine turns over
quickly.
The engine turns over
slowly.
The battery is good.Check the battery lead connections,
and have a Yamaha dealer charge
the battery if necessary.
DryWet
Open the throttle halfway and operate
the electric starter.
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10
EBU25861
CLEANING AND STORAGE
EBU25903CleaningFrequent, thorough cleaning of your ATV will not
only enhance its appearance but will improve its
general performance and extend the useful life of
many components.1. Before cleaning the ATV: a. Block off the end of the exhaust pipe toprevent water entry. A plastic bag and
strong rubber band may be used.
b. Make sure the spark plug and all filler caps are properly installed.
2. If the engine case is excessively greasy, apply degreaser with a paint brush. Do not apply
degreaser to the chain, sprockets or wheel
axles.
3. Rinse the dirt and degreaser off with a garden hose. Use only enough pressure to do the
job. WARNING! Wet brakes may have re-
duced stopping ability, increasing the
chance of an accident. Test the brakes af-
ter washing. Apply the brakes several
times at slow speeds to let friction dry out
the linings.
[EWB02312]
NOTICE: Excessive wa- ter pressure may cause water seepage
and deterioration of wheel bearings,
brakes, transmission seals and electrical
devices. Many expensive repair bills have
resulted from improper high-pressure de-
tergent applications such as those avail-
able in coin-operated car washers.
[ECB00712]
4. Once most of the dirt has been hosed off,
wash all surfaces with warm water and mild,
detergent-type soap. An old toothbrush or
bottle brush is handy for hard-to-reach pla-
ces.
5. Rinse the ATV off immediately with clean wa- ter and dry all surfaces with a chamois, clean
towel or soft absorbing cloth.
6. Dry the chain and lubricate it to prevent it from rusting.
7. Clean the seat with a vinyl upholstery cleaner to keep the cover pliable and glossy.
8. Automotive type wax may be applied to all painted and chrome plated surfaces. Avoid
combination cleaner-waxes. Many contain
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10-2
10abrasives which may mar the paint or protec-
tive finish. When finished cleaning, start the
engine and let it idle for several minutes.
EBU30362StorageShort-term
Always store your ATV in a cool, dry place and, if
necessary, protect it against dust with a porous
cover.
NOTICE: Storing the ATV in a poorly ven-
tilated room or covering it with a tarp while it is
still wet, will allow water and humidity to seep
in and cause rust. To prevent corrosion, avoid
damp cellars, stables (because of the presence
of ammonia) and areas where strong chemi-
cals are stored.
[ECB00722]
Long-term
Before storing your ATV for several months: 1. Make any necessary repairs and perform all outstanding maintenance.
2. Follow all the instructions in the Cleaning sec- tion of this chapter. 3. Fill up the fuel tank and add fuel stabilizer (Fu-
el Med Rx if available), and then run the en-
gine for 5 minutes to distribute the treated
fuel.
4. Turn the fuel cock lever off, and then drain the carburetor float chamber by loosening the
drain bolt. Pour the drained fuel into the fuel
tank.
5. Perform the following steps to protect the en- gine from internal corrosion.a. Remove the spark plug cap and spark plug.
b. Pour a teaspoonful of engine oil into the spark plug bore.
c. Install the spark plug cap onto the spark plug, and then place the spark plug on the
cylinder head so that the electrodes are
grounded. (This will limit sparking during
the next step.)
d. Turn the engine over several times with the starter. (This will coat the cylinder wall
with oil.)
Specified amount:
7.5 ml per liter of fuel (1 oz per gallon)UBD365E0.book Page 2 Monday, January 27, 2020 9:05 AM

10-3
10
e. Install the spark plug and the spark plug
cap.
6. Lubricate all control cables and the pivoting points of all levers.
7. Put the frame on stands or blocks to raise all wheels off the ground. (Alternatively, turn the
wheels each month to prevent the tires from
degrading in one spot.)
8. Cover the muffler outlet with a plastic bag to prevent moisture from entering it.
9. Remove the battery and fully charge it. (See page 9-31.)
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11
EBU25964
SPECIFICATIONS
Dimensions:Overall length:1485 mm (58.5 in)
Overall width: 1020 mm (40.2 in)
Overall height:
955 mm (37.6 in)
Seat height: 750 mm (29.5 in)
Wheelbase: 1030 mm (40.6 in)
Ground clearance:
210 mm (8.3 in)
Minimum turning radius: 3.0 m (9.84 ft)
Maximum water depth: 20 cm (8 in)Weight:Curb weight:126.5 kg (279 lb)Loading:Maximum load:
82.0 kg (181 lb)
(Total weight of rider, cargo, accessories, and tongue)Noise and vibration level:Noise level (77/311/EEC):73.0 dB(A) at 3500 r/min Uncertainty of measurement:
0.4 dB(A)
Vibration on seat (EN1032, ISO5008): 1.5 m/s²
Uncertainty of measurement: 0.3 m/s²
Vibration on handle (EN1032, ISO5008):
5.2 m/s²
Uncertainty of measurement: 1.3 m/s²
Engine:Combustion cycle:
4-stroke
Cooling system: Air cooled
Valve train: SOHC
Number of cylinders:
Single cylinder
Displacement: 90 cm³
Bore × stroke:
47.0 × 51.8 mm (1.85 × 2.04 in)
Compression ratio:
9.2 : 1
Starting system: Electric starter and kickstarter
Lubrication system: Wet sump
UBD365E0.book Page 1 Monday, January 27, 2020 9:05 AM