tire type YAMAHA WR 250F 2015 Owners Manual

CHASSIS SPECIFICATIONS
2-8
EAS2GB2065
CHASSIS SPECIFICATIONS
Chassis
Frame type Semi double cradle
Caster angle 26.33 °
Trail 114 mm (4.5 in)
Front wheel
Wheel type Spoke wheel
Rim size 21  1.60
Rim material Aluminum
Wheel travel 310 mm (12.2 in)
Radial wheel runout limit 2.0 mm (0.08 in)
Lateral wheel runout limit 2.0 mm (0.08 in)
Wheel axle bending limit 0.50 mm (0.02 in)
Rear wheel
Wheel type Spoke wheel
Rim size 18  2.15
Rim material Aluminum
Wheel travel 318 mm (12.4 in)
Radial wheel runout limit 2.0 mm (0.08 in)
Lateral wheel runout limit 2.0 mm (0.08 in)
Wheel axle bending limit 0.50 mm (0.02 in)
Front tire
Type With tube
Size 80/100-21 51M (USA) (CAN)
90/90-21 M/C 54M M+S (EUR) (AUS) (NZL)
(ZAF)
Manufacturer/model DUNLOP/GEOMAX MX51FA (USA) (CAN)
PIRELLI/SIX DAYS EXTREME (EUR) (AUS)
(NZL) (ZAF)
Rear tire
Type With tube
Size 110/100-18 64M (USA) (CAN)
130/90-18 M/C 69M M+S (EUR) (AUS) (NZL)
(ZAF)
Manufacturer/model DUNLOP/GEOMAX MX51 (USA) (CAN)
PIRELLI/SIX DAYS EXTREME (EUR) (AUS)
(NZL) (ZAF)
Tire air pressure (measured on cold tires)
Front 100 kPa (1.00 kgf/cm2, 15 psi)
Rear 100 kPa (1.00 kgf/cm2, 15 psi)
Front brake
Type Single disc brake
Operation Right hand operation
Front disc brake
Disc outside diameter  thickness 250  3.0 mm (9.8  0.12 in)
Brake disc thickness limit 2.5 mm (0.10 in)
Brake disc runout limit (as measured on wheel) 0.15 mm (0.0059 in)
Brake pad lining thickness (inner) 4.4 mm (0.17 in)
Limit 1.0 mm (0.04 in)

CHASSIS
4-1
EAS2GB2138
CHASSIS
EAS2GB2139SELECTION OF THE SECONDARY REDUC-
TION RATIO (SPROCKET)
reduction ratio>
• It is generally said that the secondary gear ra-
tio should be reduced for a longer straight por-
tion of a speed course and should be
increased for a course with many corners. Ac-
tually, however, as the speed depends on the
ground condition of the day of the race, be
sure to run through the circuit to set the ma-
chine suitable for the entire course.
• In actuality, it is very difficult to achieve set-
tings suitable for the entire course and some
settings may be sacrificed. Thus, the settings
should be matched to the portion of the
course that has the greatest effect on the race
result. In such a case, run through the entire
course while making notes of lap times to find
the best balance; then, determine the second-
ary reduction ratio.
• If a course has a long straight portion where a
machine can run at maximum speed, the ma-
chine is generally set such that it can develop
its maximum revolutions toward the end of the
straight line, with care taken to avoid the en-
gine over-revving.
TIP
Riding technique varies from rider to rider and
the performance of a machine also vary from
machine to machine. Therefore, do not imitate
other rider’s settings from the beginning but
choose your own setting according to the level
of your riding technique.
EAS2GB2140
DRIVE AND REAR WHEEL SPROCKETS
SETTING PARTS
EAS2GB2141TIRE PRESSURE
Tire pressure should be adjusted to suit the
road surface condition of the circuit.
• Under a rainy, a muddy, a sandy, or a slippery
condition, the tire pressure should be lower
for a larger area of contact with the road sur-
face. Secondary reduction ratio = Number of
rear wheel sprocket teeth/Number of
drive sprocket teeth
Secondary reduction ratio
3.846 (50/13)
Part name Type Part number
Drive sprocket “1”
(STD) 13T 9383B-13218
Rear wheel sprock-
et “2”
48T 5GS-25448-50
(STD) 50T 5TJ-25450-80
52T 5TJ-25452-80
Standard tire pressure
100 kPa (1.0 kgf/cm
2,15 psi)
Extent of adjustment
60–80 kPa (0.6–0.8 kgf/cm
2, 9.0–
12 psi)

REAR BRAKE
5-30
EWA
WARNING
• Use only the designated brake fluid. Other
brake fluids may cause the rubber seals to
deteriorate, causing leakage and poor
brake performance.
• Refill with the same type of brake fluid that
is already in the system. Mixing brake flu-
ids may result in a harmful chemical reac-
tion, leading to poor brake performance.
• When refilling, be careful that water does
not enter the brake fluid reservoir. Water
will significantly lower the boiling point of
the brake fluid and could cause vapor
lock.
ECA
NOTICE
Brake fluid may damage painted surfaces
and plastic parts. Therefore, always clean
up any spilt brake fluid immediately.
5. Bleed:
• Brake system
Refer to “BLEEDING THE BRAKE SYS-
TEM” on page 3-24.
6. Check:
• Brake fluid level
The minimum level mark “a” or below 
Add.
Refer to “CHECKING THE BRAKE FLUID
LEVEL” on page 3-29.
7. Check:
• Brake pedal operation
A softy or spongy feeling  Bleed the brake
system.
Refer to “BLEEDING THE BRAKE SYS-
TEM” on page 3-24.
EAS2GB2191REMOVING THE REAR BRAKE MASTER
CYLINDER
TIP
Before removing the rear brake master cylin-
der, drain the brake fluid from the entire brake
system.1. Remove:
• Union bolt
• Copper washers
• Brake hose
TIP
To drain any remaining brake fluid, place a con-
tainer under the master cylinder and the end of
the brake hose.
EAS2GB2192CHECKING THE REAR BRAKE MASTER
CYLINDER
1. Check:
• Brake master cylinder “1”
Damage/scratches/wear  Replace.
• Brake fluid delivery passages “2”
(brake master cylinder body)
Obstruction  Blow out with compressed
air.
2. Check:
• Brake master cylinder kit
Damage/wear  Replace.
3. Check:
• Master cylinder reservoir cap
Crack/damage  Replace.
• Brake master cylinder reservoir diaphragm
holder
• Brake master cylinder reservoir diaphragm
Crack/damage  Replace.
4. Check:
• Brake hoses
Cracks/damage/wear  Replace.
EAS2GB2193ASSEMBLING THE REAR BRAKE MASTER
CYLINDER
EWA
WARNING
• Before installation, all internal brake com-
ponents should be cleaned and lubricated
with clean or new brake fluid.
• Never use solvents on internal brake com-
ponents.
a
1
2