engine YAMAHA WR 250F 2017 Owners Manual

KICKSTATER
6-53
3. Install:
• Spring guide “1”
TIP
Slide the spring guide into the kick shaft, make
sure the groove “a” in the spring guide fits on
the stopper of the torsion spring.
4. Install:
• Kick shaft assembly “1”
TIP
• Before installation, apply molybdenum disul-
fide grease to the contacting surfaces of the
kick shaft ratchet wheel guide “2” and the kick
shaft stopper “a”.
• Apply the engine oil on the kick shaft.
• Slide the kick shaft assembly into the crank-
case and make sure the kick shaft stopper “a”
fits into the kick shaft ratchet wheel guide.5. Install:
• Torsion spring “1”
TIP
Turn the torsion spring clockwise and hook into
the proper hole “a” in the crankcase.
EAS2GBB286INSTALLING THE KICK IDLE GEAR
1. Install:
• Kick idle gear “1”
• Washer “2”
• Circlip “3”
TIP
• Apply the engine oil on the kick idle gear inner
circumference.
• Install the kick idle gear with its depressed
side “a” toward you.
1 2a b
New

SHIFT SHAFT
6-57
EAS2GBB294INSTALLING THE SEGMENT
1. Install:
• Segment “1”
• Segment bolt
TIP
• Align the notch “a” on the segment with the
pin “b” on the shift cam.
• With the stopper lever pushed down, install
the segment.
ECA
NOTICE
If the segment gets an impact, the stopper
lever may be damaged. Take care not to
give an impact to it when tightening the bolt.
EAS2GBB295INSTALLING THE SHIFT GUIDE AND SHIFT
LEVER ASSEMBLY
1. Install:
• Spring “1”
• Pawl pin “2”
•Pawl “3”
(to the shift lever “4”)
TIP
Apply the engine oil on the spring, pawl pin and
pawl.
2. Install:
• Shift lever assembly “1”
(to the shift guide “2”)
3. Install:
• Shift lever assembly “1”
• Shift guide “2”
TIP
• The shift lever assembly is installed at the
same time as the shift guide.
• Apply the engine oil on the segment bolt shaft.
4. Tighten:
• Shift guide bolt “1” Bolt (stopper lever)
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
LOCTITE®
Segment bolt
30 Nm (3.0 m·kgf, 22 ft·lbf)
T R..
2 1
3
4
LT
T R..
Shift guide bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
LOCTITE®
1
2
1 2
T R..

SHIFT SHAFT
6-58
EAS2GBB296INSTALLING THE SHIFT SHAFT
1. Install:
• Roller “1”
• Shift shaft spring “2” (to shift shaft)
• Collar “3” (to shift shaft)
• Shift shaft “4”
TIP
Apply the engine oil on the roller, collar and
shift shaft.
2. Install:
• Oil seal
EAS2GBB297INSTALLING THE SHIFT PEDAL
1. Install:
• Shift pedal “1”
• Shift pedal bolt “2”
TIP
Align the punch mark “a” on the shift shaft with
the punch mark “b” in the shift pedal.Shift pedal bolt
12 Nm (1.2 m·kgf, 8.7 ft·lbf)
1 1
LT
E
E
1
23
4
New
T R..
a
12b

OIL PUMP AND BALANCER GEAR
6-63
3. Check:
• Oil pump operation
Rough movement  Repeat steps (1) and
(2) or replace the defective part(s).
EAS2GBB303ASSEMBLING THE OIL PUMP
1. Install:
• Oil pump drive shaft “1”
• Inner rotor “2”
• Dowel pin “3”
TIP
• Apply the engine oil on the oil pump drive
shaft and inner rotor.
• Fit the dowel pin into the groove in the inner
rotor.
2. Install:
• Outer rotor “1”
TIP
Apply the engine oil on the outer rotor.
3. Install:
• Oil pump cover “1”
• Oil pump cover screw “2”
EAS2GBB304INSTALLING THE OIL PUMP AND BALANC-
ER GEAR
1. Install:
• Oil pump assembly “1”
• Oil pump assembly bolt “2” Inner-rotor-to-outer-rotor-tip
clearance
0.000–0.150 mm (0.000–0.0059
in)
Limit
0.23 mm (0.0091 in)
Outer-rotor-to-oil-pump-housing
clearance
0.13–0.18 mm (0.0051–0.0071 in)
Limit
0.25 mm (0.0098 in)
Oil-pump-housing-to-inner-and-
outer-rotor clearance
0.06–0.11 mm (0.0024–0.0043 in)
Limit
0.18 mm (0.0071 in)
1. Inner rotor
2. Outer rotor
3. Oil pump housing
b
a 1
2
3
c
Oil pump cover screw
2.0 Nm (0.20 m·kgf, 1.4 ft·lbf)
21
3
1
E
T R..
2
1

OIL PUMP AND BALANCER GEAR
6-64
ECA
NOTICE
After tightening the bolts, make sure that
the oil pump turns smoothly.
2. Install:
• Collar “1”
• Balancer weight gear “2”
TIP
Install the balancer weight gear and balancer
shaft with their lower splines “a” aligning with
each other.
3. Install:
• Balancer drive gear “1”
• Collar “2”
TIP
• Align the punched mark “a” on the balancer
drive gear with the punched mark “b” on the
balancer weight gear.
• Install the balancer drive gear and crankshaft
with the lower splines “c” aligning with each
other.4. Install:
• Conical washer “1”
• Balancer weight gear nut “2”
• Primary drive gear “3”
• Conical washer “4”
• Primary drive gear nut “5”
•Balancer “6”
• Conical washer “7”
• Balancer nut “8”
TIP
• Apply engine oil to the contact surface and
threaded portion of the primary drive gear nut.
• Place an aluminum plate “a” between the
teeth of the balancer drive gear “9” and bal-
ancer weight gear “10”.
• Install the conical washer with its convex sur-
face “b” outward.
• Align the balancer flat portion “c” with the flat
portion “d”.
• Apply the engine oil to the contact surface and
threaded portion of the balancer nut. Oil pump assembly bolt
5 Nm (0.5 m·kgf, 3.6 ft·lbf)
LOCTITE®
T R..
1
2
LT
21
Balancer weight gear nut
50 Nm (5.0 m·kgf, 36 ft·lbf)
Primary drive gear nut
75 Nm (7.5 m·kgf, 54 ft·lbf)
Balancer nut
38 Nm (3.8 m·kgf, 27 ft·lbf)
1
2
New
T R..
New
T R..
New
T R..

GENERATOR AND STARTER CLUTCH
6-66
EAS2GBB305
GENERATOR AND STARTER CLUTCH
Removing the generator
Order Job/Parts to remove Q’ty Remarks
Drain the engine oil.Refer to “CHANGING THE ENGINE OIL” on
page 3-17.
Seat and fuel tankRefer to “GENERAL CHASSIS” on page 5-1
and “FUEL TANK” on page 8-1.
Disconnect the AC magneto lead.
Clutch cable
Shift pedal Refer to “SHIFT SHAFT” on page 6-54.
1 Cover (Damper assembly) 1
2 Damper assembly 1
3 Breather hose 1
4 Left crankcase cover 1
5Gasket 1
6 Dowel pin 2
7 Starter idle gear 1
8 Bearing 1
9 Starter idle gear shaft 1
10 Generator rotor 1
T R..
T R..
6
611
9
8
7
2
3
1
14
4 5
12
10
13
T R..
T R..
T R..LTT R..
T R..
15

GENERATOR AND STARTER CLUTCH
6-69
• Crankshaft position sensor “3”
• Holder “4”
• Crankshaft position sensor bolt “5”
TIP
• Pass the AC magneto lead “6” and crankshaft
position sensor lead “7” under the holder as
shown.
• Tighten the stator bolt using the T25 bit.
• Apply the sealant to the grommet of the AC
magneto lead.
2. Install
• Starter clutch drive gear “1”
TIP
Apply the engine oil on the starter clutch drive
gear inner circumference.3. Install:
• Starter clutch “1”
To generator rotor “2”.
EAS2GBB309INSTALLING THE GENERATOR
1. Install:
• Woodruff key “1”
• Generator rotor “2”
TIP
• Clean the contact surfaces of the tapered por-
tions of the crankshaft and generator rotor.
• When installing the woodruff key, make sure
that its flat surface “a” is in parallel with the
crankshaft center line “b”.
• When installing the generator rotor, align the
keyway “c” of the generator rotor with the
woodruff key. Stator bolt
7 Nm (0.7 m·kgf, 5.1 ft·lbf)
LOCTITE®
Crankshaft position sensor bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Yamaha bond No.1215
90890-85505
(Three bond No.1215®)
T R..
T R..
6
7
1
3
22
5
5
4LT
Starter clutch bolt
16 Nm (1.6 m·kgf, 12 ft·lbf)
LOCTITE®
21
LT
T R..
2 C1 1
1a b

GENERATOR AND STARTER CLUTCH
6-70
2. Install:
• Washer
• Generator rotor nut “1”
3. Install:
• Starter idle gear shaft “1”
• Bearing “2”
• Starter idle gear 2 “3”
TIP
Apply the engine oil on the starter idle gear
shaft, bearing and idle gear inner circumfer-
ence.
4. Install:
• Dowel pin
• Crankcase cover gasket
• Left crankcase cover “1”
• Lead holder “2”
• Crankcase cover bolt
• Neutral switch lead “3”
TIP
• Pass the AC magneto lead “4” under the left
crankcase cover “a” as shown.
• Tighten the bolts in stage, using a crisscross
pattern.5. Install:
• Washer “1”
• Damper assembly “2”
• Washer “3”
TIP
Apply the engine oil to the shaft and washers.
6. Install:
• Cover (damper assembly) “1”
• Bracket “2”
•Bolt “3”
• Breather hose 2 “4”
TIP
Install the cover (damper assembly) with its
mark “a” facing upward. Generator rotor nut
65 Nm (6.5 m·kgf, 47 ft·lbf)
Crankcase cover bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
T R..
1
1
21
2
3
New
T R..Bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
4
1a
1
2
3
21
2
3
T R..

CRANKCASE
6-72
EAS2GBB310
CRANKCASE
Separating the crankcase
Order Part name Q’ty Remarks
Engine Refer to “ENGINE REMOVAL” on page 6-1.
PistonRefer to “CYLINDER AND PISTON” on page
6-32.
BalancerRefer to “OIL PUMP AND BALANCER
GEAR” on page 6-59.
Kick shaft assembly Refer to “KICKSTATER” on page 6-51.
Segment Refer to “SHIFT SHAFT” on page 6-54.
Generator rotorRefer to “GENERATOR AND STARTER
CLUTCH” on page 6-66.
1 Timing chain guide (exhaust side) 1
2 Timing chain guide stopper plate 1
3 Timing chain 1
4 Bolt [L = 45 mm (1.77 in)] 7
5 Bolt [L = 60 mm (2.36 in)] 2
6 Bolt [L = 75 mm (2.95 in)] 3
7 Right crankcase 1
8 Left crankcase 1
9 Dowel pin 2
3
1 5
2
6410 56
4
4
446
9117
8
9
LT
12
LT
10 Nm (1.0 m kgf, 7.2 ft Ibf)T.R.
12 Nm (1.2 m kgf, 8.7 ft Ibf)T.R.
12 Nm (1.2 m kgf, 8.7 ft Ibf)T.R.
12 Nm (1.2 m kgf, 8.7 ft Ibf)T.R.
5 Nm (0.5 m kgf, 3.6 ft Ibf)T.R.

CRANKCASE
6-75
EAS2GBB311DISASSEMBLING THE CRANKCASE
1. Separate:
• Right crankcase
• Left crankcase
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Remove the crankcase bolts.
TIP
Loosen each bolt 1/4 of a turn at a time and af-
ter all the bolts are loosened, remove them.
b. Remove the right crankcase “1”.
TIP
• Place the crankcase with its left side down-
ward and split it by inserting a screwdriver tip
into the splitting slit “a” in the crankcase.
• Lift the right crankcase horizontally while light-
ly patting the crankcase splitting slit and the
engine mounting boss using a soft hammer,
and leave the crankshaft and the transmission
with the left crankcase.
ECA
NOTICE
Use soft hammer to tap on the case half.
Tap only on reinforced portions of case. Do
not tap on gasket mating surface. Work
slowly and carefully. Make sure the case
halves separate evenly. If the cases do not
separate, check for a remaining case bolt or
fitting. Do not force.c. Remove the dowel pins and O-ring.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS2GBB312REMOVING THE CRANKCASE BEARING
1. Remove:
• Bearing “1”
TIP
• Remove the bearing from the crankcase by
pressing its inner race.
• Do not use the removed bearing.
EAS2GBB313CHECKING THE TIMING CHAIN, TIMING
CHAIN GUIDE, OIL STRAINER
1. Check:
• Timing chain
Stiffness  Replace the camshaft sprocket,
timing chain and crankshaft sprocket as a
set.
2. Check:
• Timing chain guide
Damage/wear  Replace
EAS2GBB314CHECKING THE CRANKCASE
1. Wash:
• Crankcase
TIP
• Wash the crankcase in a mild solvent.
• Remove any remaining gasket from the
crankcase mating surface.
1
a