compression ratio YAMAHA WR 250F 2012 Owners Manual

2-1
GENERAL SPECIFICATIONS
SPECIFICATIONS
GENERAL SPECIFICATIONS
Model name: WR250FB (USA, CDN, AUS, NZ)
WR250F (EUROPE, ZA)
Model code number: 1HC5 (USA)
1HC6 (CDN)
1HC7 (EUROPE)
1HC8 (AUS, NZ, ZA)
Dimensions: USA, CDN, ZA AUS, NZ EUROPE
Overall length 2,165 mm (85.24
in)2,175 mm (85.63
in)2,185 mm (86.02
in)
Overall width 825 mm (32.48 in)←←
Overall height 1,300 mm (51.18
in)1,305 mm (51.38
in)←
Seat height 980 mm (38.58 in) 990 mm (38.98 in)←
Wheelbase 1,480 mm (58.27
in)←1,485 mm (58.46
in)
Minimum ground clearance 365 mm (14.37 in)←←
Weight:
USA CDN, AUS, NZ,
ZAEUROPE
Curb weight
115 kg (254 lb)116 kg (256 lb) 117 kg (258 lb)
Engine:
Engine type Liquid cooled 4-stroke, DOHC
Cylinder arrangement Single cylinder
Displacement 250 cm
3 (8.80 Imp oz, 8.45 US oz)
Bore × stroke 77.0 × 53.6 mm (3.03 × 2.11 in)
Compression ratio 12.5 : 1
Starting system Kick and electric starter
Lubrication system: Dry sump
Oil type or grade:
Engine oil Recommended brand: YAMALUBE
SAE 10W-30, SAE 10W-40, SAE 10W-50,
SAE 15W-40, SAE 20W-40 or SAE 20W-50
API service SG type or higher,
JASO standard MA
Oil capacity:
Engine oil
Periodic oil change 1.1 L (0.97 Imp qt, 1.16 US qt)
With oil filter replacement 1.2 L (1.06 Imp qt, 1.27 US qt)
Total amount 1.4 L (1.23 Imp qt, 1.48 US qt)
Coolant capacity (including all routes): 0.99 L (0.87 Imp qt, 1.05 US qt)
Air filter: Wet type element

4-5
CHASSIS
CHASSIS
SELECTION OF THE SECONDARY
REDUCTION RATIO (SPROCKET)
ondary gear reduction ratio>
• It is generally said that the second-
ary gear ratio should be reduced for
a longer straight portion of a speed
course and should be increased for
a course with many corners. Actual-
ly, however, as the speed depends
on the ground condition of the day
of the ride, be sure to run through
the circuit to set the machine suit-
able for the entire course.
• In actuality, it is very difficult to
achieve settings suitable for the en-
tire course and some settings may
be sacrificed. Thus, the settings
should be matched to the portion of
the course that has the greatest ef-
fect on the ride result. In such a
case, run through the entire course
while making notes of lap times to
find the best balance; then, deter-
mine the secondary reduction ratio.
• If a course has a long straight por-
tion where a machine can run at
maximum speed, the machine is
generally set such that it can devel-
op its maximum revolutions toward
the end of the straight line, with care
taken to avoid the engine over-rev-
ving.
Riding technique varies from rider to
rider and the performance of a ma-
chine also vary from machine to ma-
chine. Therefore, do not imitate other
rider's settings from the beginning but
choose your own setting according to
the level of your riding technique.
DRIVE AND REAR WHEEL
SPROCKETS SETTING PARTS
TIRE PRESSURE
Tire pressure should be adjust to suit
the road surface condition of the cir-
cuit.
• Under a rainy, muddy, sandy, or
slippery condition, the tire pressure
should be lower for a larger area of
contact with the road surface.• Under a stony or hard road condi-
tion, the tire pressure should be
higher to prevent a flat tire.
FRONT FORK SETTING
The front fork setting should be made
depending on the rider's feeling of an
actual run and the circuit conditions.
The front fork setting includes the fol-
lowing three factors:
1. Setting of air spring characteris-
tics
• Change the fork oil level.
2. Setting of spring preload
• Change the spring.
• Install the adjustment washer.
3. Setting of damping force
• Change the compression damp-
ing.
• Change the rebound damping.
The spring acts on the load and
the damping force acts on the
cushion travel speed.
CHANGE IN LEVEL AND
CHARACTERISTICS OF FORK OIL
Damping characteristic near the final
stroke can be changed by changing
the fork oil amount.
Adjust the oil level in 5 mm (0.2 in)
increments or decrements. Too
low oil level causes the front fork
to produce a noise at full rebound
or the rider to feel some pressure
on his hands or body. Alternative-
ly, too high oil level will develop
unexpectedly early oil lock with
the consequent shorter front fork
travel and deteriorated perfor-
mance and characteristics. There-
fore, adjust the front fork within
the specified range.
Secondary reduction ratio =
Number of rear wheel sprocket
teeth/Number of drive sprocket
teeth
Standard secondary
reduction ratio50/13
(3.846)
* 47/14
(3.357)
* For EUROPE
Part
nameSize Part number
Drive
sprocket
"1"
(STD) 13T 9383B-13218
** (STD) * 14T 9383B-14222
Rear
wheel
sprocket
"2"
** (STD) ** 47T 1C3-25447-00
48T 5GS-25448-50
* 48T 1C3-25448-00
* 49T 1C3-25449-00
(STD) 50T 5TJ-25450-80
* (STD) * 50T 1C3-25450-00
* 51T 1C3-25451-00
52T 5TJ-25452-80
* 52T 1C3-25452-00
* For AUS and NZ
** For EUROPE
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)
Extent of adjustment:
100–120 kPa (1.0–1.2
kgf/cm
2, 15–18 psi)
Standard oil level:
132 mm (5.20 in)
Extent of adjustment:
95–150 mm (3.74–5.91
in)
From top of outer tube
with inner tube and
damper rod fully com-
pressed without
spring.