2017 YAMAHA YFM90 engine

8-21
8
4. Tighten the locknut.
5. Slide the rubber covers to their original posi-
tions.
EBU24061Valve 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 and lu-
brication 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. EBU34511Checking the front and rear brake
shoesThe front and rear brake shoes must be checked
for wear at the intervals specified in the periodic
maintenance and lubrication chart. Without disas-
sembling the brake, this can be performed by
checking the position 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.
1. Rubber cover
2. Throttle lever free play adjusting nut
3. Locknut
4. Throttle lever free play
1
3
2
1
4
(b)
(a)
UBD361E0.book Page 21 Monday, January 25, 2016 10:53 AM

8-27
8
4. To tighten the drive chain, turn the drive chain
slack adjusting nut in direction (a). To loosen
the drive chain, turn the adjusting nut in direc-
tion (b) and push the rear wheels forward.
NOTICE: Improper drive chain slack will
overload the engine as well as other vital
parts of the ATV and can lead to drive
chain slippage or breakage. To prevent
this from occurring, keep the drive chain
slack within the specified limits.
[ECB00543]
5. Tighten the locknut, and then the bolts and nuts to their specified torques. 6. Adjust the rear brake lever free play. (See
page 8-24.)
EBU24883Lubricating the drive chainThe drive chain must be cleaned and lubricated at
the intervals specified in the periodic maintenance
and lubrication chart, otherwise it will quickly wear
out, especially when riding in dusty or wet areas.
Service the drive chain as follows.NOTICEECB00562The drive chain must be lubricated after wash-
ing the ATV or riding in the rain or wet areas.
1. Drive chain slack adjusting nut
2. Locknut
1
2
(a)
(b)
Tightening torques:Locknut:22 Nm (2.2 m·kgf, 16 ft·lbf)
Bolt: 45 Nm (4.5 m·kgf, 33 ft·lbf)
Nut: 54 Nm (5.4 m·kgf, 39 ft·lbf)
UBD361E0.book Page 27 Monday, January 25, 2016 10:53 AM

8-28
81. Clean the drive chain with kerosene and a
small soft brush. NOTICE: To prevent dam-
aging the O-rings, do not clean the drive
chain with steam cleaners, high-pressure
washers or inappropriate solvents.
[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
1. O-ring
1
1
Recommended lubricant:
Yamaha cable lubricant or other suitable cable lubricant
UBD361E0.book Page 28 Monday, January 25, 2016 10:53 AM

8-36
8
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.
UBD361E0.book Page 36 Monday, January 25, 2016 10:53 AM

9-1
9
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
UBD361E0.book Page 1 Monday, January 25, 2016 10:53 AM

9-2
9abrasives which may mar the paint or protec-
tive finish. When finished cleaning, start the
engine and let it idle for several minutes.
EBU30361StorageShort-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. Follow all the instructions in the “Cleaning” section of this chapter.
2. Turn the fuel cock lever to “OFF”.
3. Drain the carburetor float chamber by loosen- ing the drain bolt; this will prevent fuel depos-
its from building up. Pour the drained fuel into
the fuel tank. 4. Fill up the fuel tank and add fuel stabilizer (if
available) to prevent the fuel from deteriorat-
ing.
5. Perform the following steps to protect the cyl- inder, piston rings, etc. from 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.)
e. Remove the spark plug cap from the spark plug, and then install the spark plug and
the spark plug cap.
6. Lubricate all control cables and the pivoting points of all levers.
Specified amount:
7.5 ml of stabilizer to each liter of fuel (or 1
oz of stabilizer to each gallon of fuel)UBD361E0.book Page 2 Monday, January 25, 2016 10:53 AM

10-1
10
EBU25962
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:
100 mm (3.9 in)
Minimum turning radius: 3000 mm (118 in)Weight:Curb weight:
126.5 kg (279 lb)Noise and vibration level:Noise level (77/311/EEC):73.0 dB(A) (EUR, FRA, GBR)
Uncertainty of measurement:
3.0 dB(A) (EUR, FRA, GBR)
Vibration on seat (EN1032, ISO5008): 0.6 m/s² (EUR, FRA, GBR)
Uncertainty of measurement: 0.3 m/s² (EUR, FRA, GBR) Vibration on handle (EN1032, ISO5008):
6.3 m/s² (EUR, FRA, GBR)
Uncertainty of measurement: 1.3 m/s² (EUR, FRA, GBR)
Engine:Engine type:
Air cooled 4-stroke, SOHC
Cylinder arrangement: Single cylinder
Displacement: 89 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 sumpEngine oil:Recommended brand:YAMALUBE
Type:
SAE 10W-30 or 20W-40
Recommended engine oil grade: API service SG type or higher, JASO standard MA
Engine oil quantity: Periodic oil change: 0.90 L (0.95 US qt, 0.79 Imp.qt)
UBD361E0.book Page 1 Monday, January 25, 2016 10:53 AM

12-1
12
INDEX
AAccessories and loading ................................................ 6-6
Air filter element, cleaning ............................................ 8-15BBattery .......................................................................... 8-31
Brake lever free play, adjusting the front ..................... 8-22
Brake lever free play (rear), adjusting ........................... 8-24
Brake lever, front ............................................................ 4-4
Brake lever, rear ............................................................. 4-5
Brake levers, checking and lubricating ........................ 8-29
Brakes .......................................................................... 8-21
Brakes, front and rear .................................................... 5-3CCables, checking and lubricating ................................. 8-28
Carburetor, adjusting ...................................................8-19
Chassis fasteners ........................................................... 5-6
Cleaning ......................................................................... 9-1DDrive chain ..................................................................... 5-3
Drive chain, lubricating ................................................ 8-27
Drive chain slack .......................................................... 8-25
Drive select lever ............................................................ 4-6
Drive select lever and driving in reverse ........................ 6-3EEngine break-in .............................................................. 6-4
Engine, cold start ........................................................... 6-1
Engine idling speed ...................................................... 8-19
Engine oil .............................................................. 5-3, 8-11
Engine, starting a warm ................................................. 6-3Engine stop switch ......................................................... 4-2
FFront and rear brake shoes, checking ......................... 8-21
Front knuckle pivots, lubricating .................................. 8-30
Fuel ........................................................................ 4-8, 5-3
Fuel cock ...................................................................... 4-10
Fuel tank cap ................................................................. 4-8
Fuse, replacing ............................................................. 8-33HHandlebar switches ....................................................... 4-2IIdentification numbers ................................................. 11-1
Indicator lights ............................................................... 4-1
Instruments and switches .............................................. 5-6KKickstarter ...................................................................... 4-7LLabel locations ............................................................... 1-1MMain switch .................................................................... 4-1
Maintenance and lubrication chart ................................ 8-5
Maintenance chart, emission control system ................ 8-3
Model label .................................................................. 11-1NNeutral indicator light ..................................................... 4-1OOwner’s manual and tool kit .......................................... 8-2PParking ........................................................................... 6-5
UBD361E0.book Page 1 Monday, January 25, 2016 10:53 AM