CHASSIS
10-1
EAM20119
CHASSIS
EAM30168
SELECTION OF THE SECONDARY
REDUCTION RATIO (SPROCKET)
<Requirement for selection of secondary gear
reduction ratio>
•
It is generally said that the secondary gear ratio
should be reduced for a longer straight portion
of a speed course and should be increased for
a course with many corners. Actually, howev-
er, as the speed depends on the ground condi-
tion of the day of the race, be sure to run
through the circuit to set the machine suitable
for the entire course.
•
In actuality, it is very difficult to achieve settings
suitable for the entire course and some set-
tings 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 secondary reduc-
tion 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.
EAM30169
DRIVE AND REAR WHEEL SPROCKETS
SETTING PARTS
EAM30170
TIRE 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 surface.
•
Under a stony or a hard road condition, the tire
pressure should be higher to prevent a flat tire.
EAM30171
FRONT FORK SETTING
The front fork setting should be made depending
Secondary reduction ratio = Number of
rear wheel sprocket teeth/Number of
drive sprocket teeth
Secondary reduction ratio
3.923 (51/13)
Part name
Type
Part number
Drive
sprocket “1”
(STD)
13T
9383B-13218
Rear wheel
sprocket “2”
48T
5GS-25448-50
50T
5TJ-25450-80
(STD)
51T
BAK-25451-00
52T
5TJ-25452-80
Standard tire pressure
100 kPa (1.00 kgf/cm², 15 psi)
Extent of adjustment
60–80 kPa (0.60–0.80 kgf/cm², 9–
12 psi)
Extent of adjustment
100–120 kPa (1.00–1.20 kgf/cm²,
15–18 psi)
Part name
Type
Part number
Summary of Contents for WR250FM 2021
Page 5: ...EAM20093 YAMAHA MOTOR CORPORATION U S A WR MOTORCYCLE LIMITED WARRANTY...
Page 8: ......
Page 10: ......
Page 52: ...MOTORCYCLE CARE AND STORAGE 1 40...
Page 62: ...ELECTRICAL SPECIFICATIONS 2 9 Radiator fan motor fuse 5 0 A Spare fuse 15 0 A...
Page 70: ...CABLE ROUTING DIAGRAM 2 17 EAM20152 CABLE ROUTING DIAGRAM Frame and engine left side view...
Page 72: ...CABLE ROUTING DIAGRAM 2 19 Frame and engine right side view...
Page 74: ...CABLE ROUTING DIAGRAM 2 21 Handlebar front view...
Page 76: ...CABLE ROUTING DIAGRAM 2 23 Frame and engine top view...
Page 78: ...CABLE ROUTING DIAGRAM 2 25 Frame and battery top view...
Page 80: ...CABLE ROUTING DIAGRAM 2 27 Rear brake right side view...
Page 82: ...CABLE ROUTING DIAGRAM 2 29 Front brake front view and right side view...
Page 84: ...CABLE ROUTING DIAGRAM 2 31 Taillight top view and right side view...
Page 86: ...CABLE ROUTING DIAGRAM 2 33...
Page 203: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 5 3 1 Oil filter element 2 Oil pump...
Page 204: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 5 4 1 Intake camshaft 2 Exhaust camshaft...
Page 278: ...TRANSMISSION 5 78...
Page 288: ...WATER PUMP 6 9...
Page 298: ...THROTTLE BODY 7 9...
Page 301: ......
Page 302: ...IGNITION SYSTEM 8 1 EAM20142 IGNITION SYSTEM EAM30277 CIRCUIT DIAGRAM...
Page 306: ...ELECTRIC STARTING SYSTEM 8 5 EAM20143 ELECTRIC STARTING SYSTEM EAM30279 CIRCUIT DIAGRAM...
Page 312: ...CHARGING SYSTEM 8 11 EAM20144 CHARGING SYSTEM EAM30282 CIRCUIT DIAGRAM...
Page 315: ...CHARGING SYSTEM 8 14...
Page 316: ...SIGNALING SYSTEM 8 15 EAM20154 SIGNALING SYSTEM EAM30348 CIRCUIT DIAGRAM...
Page 320: ...LIGHTING SYSTEM 8 19 EAM20153 LIGHTING SYSTEM EAM30346 CIRCUIT DIAGRAM...
Page 323: ...LIGHTING SYSTEM 8 22...
Page 324: ...COOLING SYSTEM 8 23 EAM20155 COOLING SYSTEM EAM30350 CIRCUIT DIAGRAM...
Page 327: ...COOLING SYSTEM 8 26...
Page 328: ...FUEL INJECTION SYSTEM 8 27 EAM20145 FUEL INJECTION SYSTEM EAM30284 CIRCUIT DIAGRAM...
Page 353: ...FUEL INJECTION SYSTEM 8 52...
Page 354: ...FUEL PUMP SYSTEM 8 53 EAM20146 FUEL PUMP SYSTEM EAM30287 CIRCUIT DIAGRAM...
Page 388: ...SELF DIAGNOSTIC FUNCTION AND DIAGNOSTIC CODE TABLE 9 15...
Page 398: ...CHASSIS 10 9...
Page 400: ......
Page 402: ......
Page 403: ...WR250FM 2021 WIRING DIAGRAM BAK 2819U 11_W D indd 1 2020 07 01 12 01 28...
Page 404: ...WR250FM 2021 WIRING DIAGRAM BAK 2819U 11_W D indd 2 2020 07 01 12 01 28...