2022 YAMAHA YFM90R warning

8-19
8The ATV can be used to cross slow moving, shal-
low water of up to a maximum of 20 cm (8 in) in
depth. Before entering the water, choose your
path carefully. Enter where there is no sharp drop
off, and avoid rocks or other obstacles which may
be slippery or upset the ATV. Drive slowly and
carefully.
Test your brakes after leaving the water. If neces-
sary, apply them several times to let friction dry
out the linings. Do not continue to ride your ATV
without verifying that you have regained proper braking ability. WARNING! Wet brakes may have
reduced stopping ability, which could cause
loss of control.
[EWB02622]
After riding your ATV in water, be sure to drain the
trapped water by removing the check hose at the
bottom of the air filter case.
NOTICE: Undrained
water can cause damage or improper opera-
tion.
[ECB00842]
Wash the ATV in fresh water if it has been operat-
ed in salt water or muddy conditions.
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8-20
8
RIDING OVER ROUGH TERRAIN
WARNING
EWB01652Riding improperly over obstacles could cause
loss of control or a collision. Before operating
in a new area, check for obstacles. Never at-
tempt to ride over large obstacles, such as
large rocks or fallen trees. When you go over
obstacles, always follow proper procedures as
described in the Owner’s Manual. Riding over rough terrain should be done with
caution. Look out for obstacles which could cause
damage to the ATV or could lead to an upset or accident. Be sure to keep your feet firmly mounted
on the footboards at all times. Avoid jumping the
ATV as loss of control and damage to the ATV may
result.
SLIDING AND SKIDDING
WARNING
EWB01663Skidding or sliding improperly may cause you
to lose control of this ATV. You may also regain
traction unexpectedly, which may cause the
ATV to overturn.

Learn to safely control skidding or sliding by
practicing at low speeds and on level,
smooth terrain.
 On extremely slippery surfaces, such as ice,
go slowly and be very cautious in order to re-
duce the chance of skidding or sliding out of
control. Care should be used when riding on loose or slip-
pery surfaces since the ATV may slide. If unex-
pected and uncorrected, sliding could lead to an
accident.
1. Air filter case check hose
1
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9-1
9
EBU28789
PERIODIC MAINTENANCE AND ADJUSTMENT
EBU21677Periodic inspection, adjustment, and lubrication
will keep your vehicle in the safest and most effi-
cient condition possible. Safety is an obligation of
the vehicle owner and operator. The most impor-
tant points of vehicle inspection, adjustment, and
lubrication are explained on the following pages.
WARNING
EWB01842Failure to properly maintain the vehicle or per-
forming maintenance activities incorrectly may
increase your risk of injury or death during ser-
vice or while using the vehicle. If you are not fa-
miliar with vehicle service, have a Yamaha
dealer perform the service.
WARNING
EWB02563Turn off the engine when performing mainte-
nance unless otherwise specified.
A running engine has moving parts that can
catch on body parts or clothing and electri-
cal parts that can cause shocks or fires. 
Running the engine while servicing can lead
to eye injury, burns, fire, or carbon monoxide
poisoning - possibly leading to death. See
page 3-6 for more information about carbon
monoxide.

WARNING
EWB02691Brake discs, calipers, drums, and linings can
become very hot during use. To avoid possible
burns, let brake components cool before
touching them. The intervals given in the periodic maintenance
charts should be considered as a general guide
under normal riding conditions. However, DE-
PENDING ON THE WEATHER, TERRAIN, GEO-
GRAPHICAL LOCATION, AND INDIVIDUAL USE,
THE MAINTENANCE INTERVALS MAY NEED TO
BE SHORTENED.
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9-16
9
1. Park the ATV on a level surface.
2. Remove the seat. (See page 5-13.)
3. Remove the air filter case cover by unhooking
the air filter case cover holders. 4. Remove the air filter element, and clean it with
solvent. WARNING! Always use parts
cleaning solvent to clean the air filter ele-
ment. Never use low-flash-point solvents
or gasoline to clean the air filter element
because the engine could catch fire or ex-
plode.
[EWB03540]
1. Air filter case check hose
1
1. Air filter case cover
2. Air filter case cover holder
1
2
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9-19
93. Tap the spark arrester lightly, and then use a
wire brush to remove any carbon deposits.
4. Insert the spark arrester into the muffler and align the bolt hole.
5. Install the tailpipe bolt and nut, and then tight- en the nut to the specified torque.
WARNING
EWB02342Always let the exhaust system cool prior to
touching exhaust components.
Do not start the engine with the spark arrester
removed. Sparks or exhaust particulate can
cause eye injury, burns, or start a fire. EBU23942Adjusting the carburetorThe carburetor should be checked and, if neces-
sary, adjusted at the intervals specified in the pe-
riodic maintenance chart. The carburetor is an
important part of the engine and requires very so-
phisticated adjustment. Therefore, most carbure-
tor adjustments should be left to a Yamaha dealer, who has the necessary professional knowledge
and experience. The adjustment described in the
following section, however, may be performed by
the owner as part of routine maintenance.
NOTICEECB00481The carburetor has been set and extensively
tested at the Yamaha factory. Changing these
settings without sufficient technical knowl-
edge may result in poor performance of or
damage to the engine. EBU24002Adjusting the engine idling speedThe engine idling speed must be checked and, if
necessary, adjusted as follows at the intervals
specified in the periodic maintenance chart.TIPA diagnostic tachometer is needed to make this
adjustment. 1. Start the engine and warm it up.TIPThe engine is warm when it quickly responds to
the throttle.
Tightening torque:
Tailpipe nut:10 N

9-21
9Periodically check the throttle lever free play and
adjust if necessary.
TIPThe engine idling speed must be checked and ad-
justed before adjusting the throttle lever free play. 1. Slide the rubber cover away from the locknut.
2. Loosen the locknut.
3. To increase the throttle lever free play, turn
the throttle lever free play adjusting nut in di-
rection (a). To decrease the throttle lever free
play, turn the adjusting nut in direction (b).
4. Tighten the locknut.
5. Slide the rubber cover to its original position.EBU24062Valve clearanceThe valve clearance changes with use, resulting in
improper air-fuel mixture and/or engine noise. To
prevent this from occurring, the valve clearance
must be adjusted by a Yamaha dealer at the inter-
vals specified in the periodic maintenance chart.
EBU29602BrakesReplacement of brake components requires pro-
fessional knowledge. Brake service should be
performed by a Yamaha dealer.
WARNING
EWB02572Operating with improperly serviced or adjust-
ed brakes could lead to a loss in braking ability
and an accident. EBU34512Checking the front and rear brake
shoesThe front and rear brake shoes must be checked
for wear at the intervals specified in the periodic
maintenance chart. Without disassembling the
brake, this can be performed by checking the po-
sition of the brake lever free play adjusting bolts or
nut.
Front brakes
To check front brake shoe wear, check the posi-
tion of the adjusting bolts. If a bolt extends more
than 12 mm (0.47 in) from its locknut, the brake
shoes need to be replaced.
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9-28
9
1. Clean the drive chain with a drive chain clean-
er and a small soft brush. NOTICE: To pre-
vent damaging the O-rings, do not clean
the drive chain with steam cleaners, high-
pressure washers or inappropriate sol-
vents.
[ECB00572]
2. Wipe the drive chain dry.
3. Thoroughly lubricate the drive chain with a special O-ring chain lubricant. NOTICE: Do
not use engine oil or any other lubricants
for the drive chain, as they may contain
substances that could damage the O-
rings.
[ECB00582]
EBU24905
Checking and lubricating the cablesThe operation and the condition of all control ca-
bles should be checked before each ride, and the
cables and cable ends should be lubricated if nec-
essary. If a cable is damaged or does not move
smoothly, have a Yamaha dealer check or replace
it.
WARNING
EWB02582 Inspect cables frequently and replace if
damaged. Corrosion can result when the ca-
ble sheaths become damaged, and cables
can also become frayed or kinked, which
could restrict the operation of controls and
lead to an accident or injury.
 Always make sure all control cables work
smoothly before you begin riding in cold
weather. If the control cables are frozen or
do not work smoothly, you could be unable
to control the ATV, which could lead to an
accident or collision. EBU28703Checking and lubricating the front and
rear brake leversThe operation of the front and rear brake levers
should be checked before each ride, and the lever
pivots should be lubricated if necessary.
Recommended lubricant: Yamaha cable lubricant or other suitable cable lubricantRecommended lubricant: Lithium-soap-based grease
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9-31
9
TIPFor parts equipped with a grease nipple, use a
grease gun. EBU34022BatteryThis model is equipped with a 12-volt VRLA
(valve-regulated lead-acid) battery. There is no
need to check the electrolyte or to add distilled
water. However, the battery lead connections
need to be checked and tightened, and the bat-
tery terminals cleaned if corroded. If the battery
seems to have discharged, recharge it as soon as
possible.TIPWear gloves and eye protection in a ventilated
area away from sparks and open flames. Wash
hands after handling.
 It is recommended to have the battery serviced
by a Yamaha dealer.
WARNING
EWB02161Battery electrolyte is poisonous and danger-
ous, as it contains sulfuric acid, which can
cause severe burns. Avoid contact with skin,
eyes or clothing. Always shield your eyes when
working near batteries.
Antidote:
EXTERNAL: Flush with water.
INTERNAL: Drink large quantities of water or
milk. Follow with milk of magnesia, beaten egg
or vegetable oil. Call a physician immediately.
EYES: Flush with water for 15 minutes and get
prompt medical attention.
Batteries produce explosive gases. Keep
sparks, flame, cigarettes or other sources of
ignition away. Ventilate when charging or using
in an enclosed space.
KEEP OUT OF REACH OF CHILDREN. To remove the battery
1. Remove the seat. (See page 5-13.)
2. Unhook the battery band.
UBD366E0.book Page 31 Thursday, June 10, 2021 2:39 PM