tire size YAMAHA YFM90R 2009 Owners Manual

1-3
1
Avoid crossing the side of a steep hill if possible.Always use proper procedures if you stall or roll
backwards when climbing a hill. To avoid stall-
ing, use the proper gear and maintain a steady
speed when climbing a hill. If you stall or roll
backwards, follow the special procedure for
braking described in this manual. Dismount on
the uphill side or to a side if pointed straight up-
hill. Turn the ATV around and remount, following
the procedure described in this manual.Always check for obstacles before operating in a
new area.Never attempt to operate over large obstacles,
such as large rocks or fallen trees. Always follow
proper procedures when operating over obsta-
cles as described in this manual.Always be careful when skidding or sliding.
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 con-
trol.Never operate an ATV in fast flowing water or in
water deeper than that recommended in this
manual. Remember that wet brakes may havereduced stopping ability. Test your brakes after
leaving water. If necessary, apply them several
times to let friction dry out the linings.
Always use the size and type of tires specified in
this manual.Always maintain proper tire pressure as de-
scribed in this manual.Never modify an ATV through improper installa-
tion or use of accessories.Never exceed the stated load capacity for an
ATV. Cargo should be properly distributed and
securely attached. Reduce speed and follow in-
structions in this manual for carrying cargo or
pulling a trailer. Allow greater distance for brak-
ing.
WARNING
Always turn off the engine when refueling.Do not refuel right after the engine has been
running and is still very hot.Do not spill gasoline on the engine or ex-
haust pipe/muffler when refueling. Never re-
fuel while smoking, or in the vicinity of
sparks, open flames, or other sources of ig-
nition such as the pilot lights of water heat-
ers and clothes dryers. Gasoline can catch

5-4
Tires

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 brakes for wear. (See pages 8-22 and 8-25.)
5
WARNING
Throttle lever Check 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.
WARNING
Always check the brakes at the start of every
ride. Do not ride the ATV if you find any prob-
lem with the brakes or you could lose braking
ability, which could lead to an accident. If a
problem cannot be corrected by the adjust-
ment procedures provided in this manual, havea Yamaha dealer check for the cause.
WARNING
Use of improper tires on this ATV, or operation
of this ATV with improper or uneven tire pres-
sure, may cause loss of control, increasing
your risk of accident.
Pay attention to the following.The tires listed below have been approved
by Yamaha Motor Co., Ltd. for this model.
Other tire combinations are not recommend-
ed.Front: Manufacturer/model:MAXXIS/M939
Size: AT18 x 7-8
Type: Tubeless
Rear: Manufacturer/model:MAXXIS/M940

5-5
5
Measuring the tire pressure Use the low-pressure tire gauge.TIPThe 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 beincorrect.
Size:
AT18 x 9-8
Type: Tubeless
The tires should be set to the recommend-
ed pressure:Recommended tire pressure: Front:25 kPa (3.6 psi) (0.25 kgf/cm
2)
Rear: 25 kPa (3.6 psi) (0.25 kgf/cm2)
Check and adjust tire pressures when
the tires are cold.Tire pressures must be equal on both
sides.
2)2)
Tire pressure below the minimum speci-
fied could cause the tire to dislodge from
the rim under severe riding conditions.Minimum tire pressure: Front:22 kPa (3.2 psi) (0.22 kgf/cm
Rear: 22 kPa (3.2 psi) (0.22 kgf/cmUse no more than the following pressures
when seating the tire beads.
Maximum tire seating pressure: Front:250 kPa (36 psi) (2.5 kgf/cm
2)
Rear: 250 kPa (36 psi) (2.5 kgf/cm2)
Higher pressures and fast inflation may
cause a tire to burst. Inflate the tires very
slowly and carefully.

7-7
Do not operate at speeds too fast for your
skills or the conditions.Speed limiters
For riders less experienced with this model, the
throttle lever housing is equipped with a vehicle
speed limiter. This speed limiter keeps the throttle
from fully opening, even when the throttle lever is
pushed to the maximum. Turning in the adjusting
screw limits the maximum engine power available
and decreases the maximum speed of the ATV.
Turning in the adjusting screw decreases top speed,
and turning it out increases top speed.
(See pages 4-3 and 4-4.)
7
This model also has an engine speed limiter plate
to limit the amount of engine power available.
WARNING

Always use the size and type tires specified in
the Owner’s Manual for this ATV on page 5-4.
Always maintain proper tire pressure as de-
scribed in the Owner’s Manual on page 5-5.
Use of improper tires on this ATV, or operation
of this ATV with improper or uneven tire pres-
sure, may cause loss of control, increasingyour risk of an accident.
WARNING
Always go at a speed that is proper for the ter-
rain, visibility and operating conditions, and
your experience. Operating this ATV at speeds
too fast for your skills or the conditions in-
creases your chances of losing control of theATV, which can result in an accident.
Yamaha recommends that all beginning riders start
off with the vehicle speed limiter turned in and the
engine speed limiter plate installed to limit the amount
of speed available while they learn. The vehicle speed
limiter may be gradually adjusted to increase maximum
speed as the beginner becomes more familiar with
operating the ATV. Parents should decide when to
adjust the ATV for more power as their youngster’s
riding skills improve. Once the ATV rider can operate
with skill at the top speed permitted by adjusting the
vehicle speed limiter alone, the engine speed limiter
plate can be removed. Since removal of this plate will

10
Engine oil quantity:Periodic oil change: 0.8 L (0.84 US qt) (0.70 Imp.qt)Final transmission oil:Type:SAE80 API GL-4 Hypoid gear oil
Quantity: 0.30 L (0.32 US qt) (0.27 Imp.qt)Air filter:Air filter element: Wet elementFuel:Recommended fuel: Regular unleaded gasoline only (EUR)
Unleaded gasoline only (AUS)(NZL)
Fuel tank capacity: 4.8 L (1.27 US gal) (1.06 lmp.gal)
Fuel reserve amount: 1.0 L (0.26 US gal) (0.22 Imp.gal)Carburetor:Manufacturer:TK
Type x quantity: SVR 22-1G x 1Spark plug (s):Manufacturer/model:NGK/CR7HSA
Spark plug gap: 0.6–0.7 mm (0.024–0.028 in)
Chassis:Frame type: Steel tube frame
Caster angle: 4.0 °
Trail: 16 mm (0.63 in)
Front tire:Type:Tubeless
Size: AT18 x 7-8
Manufacturer/model: MAXXIS/M939
Clutch:Clutch type: Dry, centrifugal automatic
Transmission:Primary reduction system: V-belt
Primary reduction ratio:
2.47-0.61:1
Secondary reduction system: Spur
Secondary reduction ratio: 41/15 × 45/13 (9.462)
Third reduction system:
Chain drive
Third reduction ratio: 28/13(2.154)
Transmission type: V-belt automatic
10
10-2

10-3
10
Rear tire:Type:Tubeless
Size: AT18 x 9-8
Manufacturer/model: MAXXIS/M940Loading:Maximum loading limit: 70.0 kg (154 lb)
(Total weight of rider, cargo, accessories, and tongue)Tire air pressure (measured on cold tires):Recommended:Front:25 kPa (3.6 psi) (0.25 kgf/cm
2)
Rear: 25 kPa (3.6 psi) (0.25 kgf/cm2)
Minimum: Front:22 kPa (3.2 psi) (0.22 kgf/cm2)
Rear: 22 kPa (3.2 psi) (0.22 kgf/cm2)
Front wheel:
Wheel type: Panel wheel
Rim size: 8 x 5.5AT
Rear wheel:Wheel type: Panel wheel
Rim size: 8 x 7ATFront brake:Type:Drum brake
Operation: Right hand operationRear brake:Type:Single disc brake
Operation: Left hand operation
Recommended fluid: DOT4Front suspension:Type:Double wishbone
Spring/shock absorber type: Coil spring/oil damper
Wheel travel:
111 mm (4.4 in)