Shift cam YAMAHA YZ250F 2007 Owners Manual

CHAPTER 4
ENGINE
SEAT, FUEL TANK
AND SIDE COVERS...................................4-1
EXHAUST PIPE AND SILENCER..............4-3
RADIATOR.................................................4-6
CARBURETOR...........................................4-9
CAMSHAFTS............................................4-22
CYLINDER HEAD.....................................4-31
VALVES AND VALVE SPRINGS.............4-34
CYLINDER AND PISTON.........................4-43
CLUTCH....................................................4-50
OIL FILTER ELEMENT, WATER PUMP
AND RIGHT CRANKCASE COVER........4-57
BALANCER..............................................4-64
OIL PUMP.................................................4-67
KICK SHAFT AND SHIFT SHAFT...........4-73
CDI MAGNETO.........................................4-80
ENGINE REMOVAL..................................4-84
CRANKCASE AND CRANKSHAFT.........4-89
TRANSMISSION, SHIFT CAM
AND SHIFT FORK....................................4-98
CHAPTER 5
CHASSIS
FRONT WHEEL AND REAR WHEEL........5-1
FRONT BRAKE AND REAR BRAKE......5-10
FRONT FORK...........................................5-26
HANDLEBAR............................................5-43
STEERING................................................5-49
SWINGARM..............................................5-54
REAR SHOCK ABSORBER.....................5-62

SPEC
2 - 8 Clutch plate thickness 1.1 ~ 1.3 mm (0.043 ~ 0.051 in) ----
Quantity 8 ----
Warp limit ---- 0.1 mm
(0.004 in)
Clutch spring free length 40.4 mm (1.59 in) 39.4 mm
(1.55 in)
Quantity 5 ----
Clutch housing thrust clearance 0.10 ~ 0.35 mm
(0.0039 ~ 0.0138 in)----
Clutch housing radial clearance 0.010 ~ 0.044 mm
(0.0004 ~ 0.0017 in)----
Clutch release method Inner push, cam push ----
Shifter:
Shifter type Cam drum and guide bar ----
Guide bar bending limit ---- 0.05 mm
(0.002 in)
Kickstarter:
Type Kick and ratchet type ----
Carburetor:
USA, CDNEUROPE, ZA,
AUS, NZ
Type/manufacturer FCR-MX37/
KEIHIN
←----
I. D. mark 5XCG G0 5XCH H0 ----
Main jet (M.J) #178
←----
Main air jet (M.A.J)ø2.0
←----
Jet needle – clip position (J.N) OBEPQ-4
←----
Cutaway (C.A) 1.5
←----
Pilot jet (P.J) #42
←----
Pilot air jet (P.A.J) #105
←----
Pilot outlet (P.O)ø0.9
←----
Pilot screw (example) (P.S) 1-7/8 2-1/8 ----
Bypass (B.P)ø1.0
←----
Valve seat size (V.S)ø3.8
←----
Starter jet (G.S) #72
←----
Leak jet (Acc.P) #80 #70 ----
Float height (F.H) 8 mm (0.31 in)
←----
Engine idle speed 1,900 ~
2,100 r/min
←----
Intake vacuum
29.3 ~ 34.7 kPa
(220 ~ 260 mmHg,
8.66 ~ 9.45 inHg)←----
Hot starter lever free play 3 ~ 6 mm
(0.12 ~ 0.24 in)
←---- Item Standard Limit
MAINTENANCE SPECIFICATIONS

3 - 2
INSP
ADJ
MAINTENANCE INTERVALS
SHIFT FORK, SHIFT CAM, GUIDE BAR
InspectInspect wear
ROTOR NUT
Retighten
EXHAUST PIPE, SILENCER, PRO-
TECTOR
Inspect and retighten
Clean
Replace * Whichever comes first
CRANK
Inspect and clean
CARBURETOR
Inspect, adjust and clean
SPARK PLUG
Inspect and clean
Replace
DRIVE CHAIN
Use chain lube
Chain slack: 48 ~ 58 mm
(1.9 ~ 2.3 in) Lubricate, slack, alignment
Replace
COOLING SYSTEM
Check coolant level and leakage
Check radiator cap operation
Replace coolant Every two years
Inspect hoses
OUTSIDE NUTS AND BOLTS Refer to “STARTING
AND BREAK-IN” section
in the CHAPTER 1. Retighten
AIR FILTER
Clean and lubricate
Use foam air-filter oil or
equivalent oil
Replace
OIL FILTER
Replace
OIL STRAINER
Clean
FRAME
Clean and inspect
FUEL TANK, COCK
Clean and inspect
BRAKES
Adjust lever position and pedal height
Lubricate pivot point
Check brake disc surface
Check fluid level and leakage
Retighten brake disc bolts, caliper
bolts, master cylinder bolts and union
bolts
Replace pads
Replace brake fluid Every one year
FRONT FORKS
Inspect and adjust
Replace oil Suspension oil “S1”
Replace oil sealItemAfter
break-inEvery
race
Every
third
(or
500 km)Every
fifth
(or
1,000 km)As re-
quiredRemarks


3

4 - 76
ENGKICK SHAFT AND SHIFT SHAFT
EC4B4400
Shift shaft
1. Inspect:
Shift shaft 1
Bend/damage → Replace.
Spring 2
Broken → Replace.
EC4C4100
Shift guide and shift lever assembly
1. Inspect:
Shift guide 1
Shift lever 2
Pawl 3
Pawl pin 4
Spring 5
Wear/damage → Replace.
EC4B4500
Stopper lever
1. Inspect:
Stopper lever 1
Wear/damage → Replace.
Torsion spring 2
Broken → Replace.
ASSEMBLY AND INSTALLATION
Segment
1. Install:
Segment 1
Bolt (segment)
NOTE:
Align the notch a on the segment with the pin
b on the shift cam.
CAUTION:
If the segment gets an impact, it may be
damaged. Take care not to give an impact
to the segment when tightening the bolt.
T R..30 Nm (3.0 m · kg, 22 ft · lb)

4 - 84
ENGENGINE REMOVAL
EC4M0000
ENGINE REMOVAL
Extent of removal Order Part name Q’ty Remarks
ENGINE REMOVAL
Preparation for removal Hold the machine by placing the
suitable stand under the frame.
WARNING
Support the machine securely so
there is no danger of it falling over.
Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Carburetor Refer to “CARBURETOR” section.
Exhaust pipe and silencer Refer to “EXHAUST PIPE AND
SILENCER” section.
Clutch cable Disconnect at engine side.
Radiator Refer to “RADIATOR” section.
Shift pedal Refer to “KICK SHAFT AND SHIFT
SHAFT” section.
Cylinder head breather hose Refer to “CAMSHAFTS” section.
Drain the engine oil. Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.
Oil hose and oil tank breather
hoseRefer to “OIL PUMP” section.

4 - 91
ENGCRANKCASE AND CRANKSHAFT
CRANKCASE BEARING
Extent of removal:
1 Crankcase bearing removal
Extent of removal Order Part name Q’ty Remarks
CRANKCASE BEARING
REMOVAL
Preparation for removal Transmission Refer to “TRANSMISSION, SHIFT
CAM AND SHIFT FORK” section.
Shift cam and shift fork
1 Oil seal 2
2 Bearing 10 Refer to “REMOVAL POINTS”.
1

4 - 98
ENGTRANSMISSION, SHIFT CAM AND SHIFT FORK
EC4H0000
TRANSMISSION, SHIFT CAM AND SHIFT FORK
Extent of removal:
1 Shift fork, shift cam, main axle and drive axle removal
Extent of removal Order Part name Q’ty Remarks
TRANSMISSION, SHIFT CAM
AND SHIFT FORK REMOVAL
Preparation for removal Engine Refer to “ENGINE REMOVAL” section.
Separate the crankcase. Refer to “CRANKCASE AND CRANK-
SHAFT” section.
1 Main axle 1
Refer to “REMOVAL POINTS”. 2 Drive axle 1
3Shift cam 1
4 Shift fork 3 1
5 Shift fork 2 1
6 Shift fork 1 1
7 Collar 1
1

4 - 99
ENGTRANSMISSION, SHIFT CAM AND SHIFT FORK
EC4H3000
REMOVAL POINTS
EC4H3230
Transmission
1. Remove:
Main axle 1
Drive axle 2
Shift cam
Shift fork 3
Shift fork 2
Shift fork 1
NOTE:
Remove assembly with the collar 3 installed
to the crankcase.
Remove assembly carefully. Note the posi-
tion of each part. Pay particular attention to
the location and direction of shift forks.
Remove the main axle, drive axle, shift cam
and shift fork all together by tapping lightly on
the transmission drive axle with a soft ham-
mer.
EC4H4000
INSPECTION
EC4H4200
Gears
1. Inspect:
Matching dog a
Gear teeth b
Shift fork groove c
Wear/damage → Replace.
2. Inspect:
O-ring 1
Damage → Replace.
3. Check:
Gears movement
Unsmooth movement → Repair or
replace.
EC4H4600
Bearing
1. Inspect:
Bearing 1
Rotate inner race with a finger.
Rough spot/seizure → Replace.

4 - 100
ENGTRANSMISSION, SHIFT CAM AND SHIFT FORK
EC4H4810
Shift fork, shift cam and segment
1. Inspect:
Shift fork 1
Wear/damage/scratches → Replace.
2. Inspect:
Shift cam 1
Segment 2
Wear/damage → Replace.
3. Check:
Shift fork movement
Unsmooth operation → Replace shift
fork.
NOTE:
For a malfunctioning shift fork, replace not only
the shift fork itself but the two gears each adja-
cent to the shift fork.
EC4H5000
ASSEMBLY AND INSTALLATION
Transmission
1. Install:
5th pinion gear (24T) 1
3rd pinion gear (20T) 2
Collar 3
4th pinion gear (22T) 4
2nd pinion gear (16T) 5
To main axle 6.
NOTE:
Apply the molybdenum disulfide oil on the
inner and end surface of the idler gear and on
the inner surface of the sliding gear, then
install.

4 - 101
ENGTRANSMISSION, SHIFT CAM AND SHIFT FORK
2. Install:
2nd wheel gear (28T) 1
4th wheel gear (27T) 2
3rd wheel gear (29T) 3
5th wheel gear (25T) 4
1st wheel gear (30T) 5
O-ring 6
To drive axle 7.
NOTE:
Apply the molybdenum disulfide oil on the
inner and end surface of the idler gear and
on the inner surface of the sliding gear, then
install.
Apply the lithium soap base grease on the O-
ring.
3. Install:
Washer 1
Circlip 2
NOTE:
Be sure the circlip sharp-edged corner a is
positioned opposite side to the washer and
gear b.
Install the circlip with its ends c settled
evenly on the spline crests.
cc
4. Install:
Collar 1
NOTE:
Apply the lithium soap base grease on the oil
seal lip.
When installing the collar into the crankcase,
pay careful attention to the crankcase oil seal
lip.