light YAMAHA YFM90R 2021 User Guide

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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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abruptly, the vehicle may lurch forward or the front
wheels may lift off the ground, resulting in a loss of
directional control. Avoid higher speeds until you
are thoroughly familiar with the operation of your
ATV.
When slowing down or stopping, release the
throttle and apply the brakes smoothly and evenly.
Improper use of the brakes can cause the tires to
lose traction, reducing control and increasing the
possibility of an accident.
TURNING YOUR ATV
WARNING
EWB01772Always follow proper procedures for turning as
described in this Owner’s Manual. Practice
turning at low speeds before attempting to turn
at faster speeds. Do not turn at speeds too fast
for your skills or the conditions. ATV could go
out of control, causing a collision or overturn. To achieve maximum traction on unpaved surfac-
es, the two rear wheels turn together at the same
speed. Therefore, unless the wheel on the inside
of the turn is allowed to slip or lose some traction,
the ATV will resist turning. A special turning tech- nique must be used to allow the ATV to make
turns quickly and easily. It is essential that this skill
be learned first at low speed.
As you approach a curve, slow down and begin to
turn the handlebars in the desired direction. As
you do so, put your weight on the footboard to the
outside of the turn (opposite your desired direc-
tion) and lean your upper body into the turn. Use
the throttle to maintain an even speed through the
turn. This maneuver will let the wheel on the inside
of the turn slip slightly, allowing the ATV to make
the turn properly.UBD365E0.book Page 12 Monday, January 27, 2020 9:05 AM

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
Never attempt to turn the ATV around on any
hill until you have mastered the turning tech-
nique as described in the Owner’s Manual on
level ground. Be very careful when turning
on any hill.
Traversing a sloping surface on your ATV requires
you to properly position your weight to maintain
proper balance. Be sure that you have learned the
basic riding skills on flat ground before attempting
to cross a sloping surface. Avoid slopes with slip-
pery surfaces or rough terrain that may upset your
balance.
As you travel across a slope, lean your body in the
uphill direction. It may be necessary to correct the
steering when riding on loose surfaces by pointing
the front wheels slightly uphill. When riding on
slopes, be sure not to make sharp turns either up
or down hill.
If your ATV does begin to tip over, gradually steer
in the downhill direction if there are no obstacles
in your path. As you regain proper balance, grad-
ually steer again in the direction you wish to travel. CROSSING THROUGH SHALLOW WATER
WARNING
EWB01642Operating this vehicle through deep or fast-
flowing water can lead to loss of control or an
overturn. To reduce your risk of drowning or
other injuries, use care when crossing through
water. Never operate this ATV water deeper
than the depth specified in your Owner’s Man-
ual, as tires may float, increasing the risk of an
overturn.
OK
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EBU23216Checking the spark plugThe spark plug is an important engine component,
which is easy to check. Since heat and deposits
will cause any spark plug to slowly erode, the
spark plug should be removed and checked in ac-
cordance with the periodic maintenance chart. In
addition, the condition of the spark plug can reveal
the condition of the engine.
To remove the spark plug1. Remove the spark plug cap.
2. Remove the spark plug as shown, with the spark plug wrench included in the tool kit. To check the spark plug
1. Check that the porcelain insulator around the center electrode of the spark plug is a medi-
um-to-light tan (the ideal color when the ATV
is ridden normally).
TIPIf the spark plug shows a distinctly different color,
the engine could be operating improperly. Do not
attempt to diagnose such problems yourself. In-
stead, have a Yamaha dealer check the ATV.
1. Spark plug cap
1
1. Spark plug wrench
1
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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

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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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Electrical system:System voltage:12 V
Ignition system:
CDI
Charging system: AC magnetoBattery:Model:
GTX5L-BS
Voltage, capacity: 12 V, 4.0 AhLights:Neutral indicator light:
3.5 W
Reverse indicator light: 3.5 WFuses:Main fuse:
7.5 AEBU30403Noise and vibration levels statement (for Eu-
rope)
The figures quoted are emission levels and are not
necessarily safe working levels. Whilst there is a
correlation between the emission and exposure
levels, this cannot be used reliably to determine
whether or not further precautions are required. Factors that influence the actual level of exposure
of work-force include the characteristics of the
work room, the other sources of noise, etc. i.e. the
number of machines and other adjacent process-
es, and the length of time for which an operator is
exposed to the noise. Also the permissible expo-
sure level can vary from country. This information,
however, will enable the user of the machine to
make a better evaluation of the hazard and risk.
EBU38670CO2 emissions levels statement (for Europe)
This CO2 measurement results from testing over a
fixed test cycle under laboratory conditions a(n)
(parent) engine representative of the engine type
(engine family) and shall not imply or express any
guarantee of the performance of a particular en-
gine.
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INDEX
AAccessories and loading ................................................ 7-6
Air filter element, cleaning ............................................ 9-15BBattery .......................................................................... 9-31
Brake lever free play, adjusting the front ..................... 9-23
Brake lever free play (rear), adjusting ........................... 9-24
Brake lever, front ............................................................ 5-5
Brake lever, rear ............................................................. 5-5
Brake levers, checking and lubricating ........................ 9-28
Brakes .......................................................................... 9-21
Brakes, front and rear .................................................... 6-3CCables, checking and lubricating ................................. 9-28
Carburetor, adjusting ...................................................9-19
Chassis fasteners ........................................................... 6-6
Cleaning ....................................................................... 10-1DDrive chain ..................................................................... 6-3
Drive chain, lubricating ................................................ 9-27
Drive chain slack .......................................................... 9-25
Drive select lever ............................................................ 5-6
Drive select lever and driving in reverse ........................ 7-3EEngine break-in .............................................................. 7-4
Engine, cold start ........................................................... 7-1
Engine idling speed ...................................................... 9-19
Engine oil .............................................................. 6-3, 9-10
Engine, starting a warm ................................................. 7-3Engine stop switch ......................................................... 5-2
FFront and rear brake shoes, checking ......................... 9-21
Front arm pivots, lubricating ........................................ 9-29
Front knuckle pivots, lubricating .................................. 9-30
Fuel ........................................................................ 5-9, 6-3
Fuel cock ...................................................................... 5-10
Fuel tank cap ................................................................. 5-8
Fuse, replacing ............................................................. 9-34HHandlebar switches ....................................................... 5-2IIdentification numbers ................................................... 1-1
Indicator lights ............................................................... 5-1
Instruments and switches .............................................. 6-6KKickstarter ...................................................................... 5-7LLabel locations ............................................................... 2-1MMain switch .................................................................... 5-1
Maintenance and lubrication chart ................................ 9-5
Maintenance chart, emission control system ................ 9-3
Model label .................................................................... 1-1NNeutral indicator light ..................................................... 5-1OOwner’s Manual and tool kit .......................................... 9-2
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PParking ........................................................................... 7-5
Parking brake ................................................................. 5-5
Parking on a slope ......................................................... 7-5
Part locations ................................................................. 4-1RReverse indicator light ................................................... 5-1
Riding your ATV ............................................................. 8-1SSafety information .......................................................... 3-1
Seat .............................................................................. 5-13
Shock absorber, rear ................................................... 5-15
Shock absorbers, front ................................................ 5-13
Spark arrester, cleaning ............................................... 9-18
Spark plug, checking ..................................................... 9-9
Specifications .............................................................. 11-1
Speed limiter .................................................................. 5-3
Starter (choke) ............................................................. 5-12
Start switch .................................................................... 5-2
Steering shaft, lubricating ............................................ 9-30
Storage ........................................................................ 10-2TThrottle lever ...........................................................5-2, 6-3
Throttle lever free play, adjusting ................................ 9-20
Tires ............................................................................... 6-3
Transmission .................................................................. 6-3
Transmission oil ........................................................... 9-14
Troubleshooting ........................................................... 9-36
Troubleshooting chart .................................................. 9-37VValve clearance ............................................................ 9-21Vehicle identification number ........................................ 1-1
WWheel hub bearings, checking .................................... 9-29
Wheel, installing ........................................................... 9-35
Wheel, removing .......................................................... 9-34YYamalube ..................................................................... 9-13
UBD365E0.book Page 2 Monday, January 27, 2020 9:05 AM