2004 YAMAHA YZ85 clutch

CHAPTER 3
REGULAR INSPECTION
AND ADJUSTMENTS
MAINTENANCE INTERVALS................... 3-1
PRE-OPERATION INSPECTION
AND MAINTENANCE................................ 3-4
ENGINE...................................................... 3-5
CHASSIS................................................. 3-16
ELECTRICAL........................................... 3-36
CHAPTER 4
ENGINE
SEAT, FUEL TANK
AND SIDE COVERS.................................. 4-1
EXHAUST PIPE AND SILENCER............. 4-2
RADIATOR................................................ 4-3
CARBURETOR AND REED VALVE......... 4-6
CYLINDER HEAD, CYLINDER
AND PISTON........................................... 4-15
CLUTCH AND PRIMARY
DRIVEN GEAR........................................ 4-26
KICK SHAFT, SHIFT SHAFT
AND PRIMARY DRIVE GEAR................. 4-33
WATER PUMP......................................... 4-41
CDI MAGNETO........................................ 4-45
ENGINE REMOVAL................................. 4-49
CRANKCASE AND CRANKSHAFT........ 4-53
TRANSMISSION, SHIFT CAM
AND SHIFT FORK................................... 4-59

GEN
INFO
1 - 1
DESCRIPTION
EC100000
GENERAL INFORMATION
EC110000
DESCRIPTION
1Clutch lever
2Engine stop switch
3Front brake lever
4Throttle grip
5Fuel tank cap
6Radiator cap
7Kickstarter crank
8Fuel tank
9Coolant drain bolt
0Rear brake pedal
ARadiator
BValve joint
CFuel cock
DAir filter
EDrive chain
FShift pedal
GStarter knob
HFront forkNOTE:

The machine you have purchased may differ
slightly from those shown in the following.

Designs and specifications are subject to
change without notice.
5PA10020
5PA10010
5PAR0001

GEN
INFO
1 - 8
SPECIAL TOOLS
YU-33975, 90890-01403 Steering nut wrench
This tool is used when tighten the steering ring nut to
specification.YU-33975 90890-01403
YM-01434, 90890-01434 Rod holder
This tool is used to hold the fork spring.YM-01434 90890-01434
YM-01437, 90890-01437
90890-01436Rod puller
Rod puller attachment (M10)
These tools are used to pull up the fork damper rod.YM-01437 90890-01437
90890-01436
YM-01442, 90890-01442 Fork seal driver
This tool is used when install the fork oil seal.YM-01442 90890-01442
YM-01454, 90890-01454 Damper rod holder
Use this tool to remove and install the damper rod.YM-01454 90890-01454
YU-3112-C, 90890-03112 Pocket tester
Use this tool to inspect the coil resistance, output
voltage and amperage.YU-3112-C 90890-03112
YM-91042, 90890-04086 Clutch holding tool
This tool is used to hold the clutch when removing or
installing the clutch boss securing nut.YM-91042 90890-04086
YM-34487
90890-06754Dynamic spark tester
Ignition checker
This instrument is necessary for checking the ignition
system components.YM-34487 90890-06754
ACC-QUICK-GS-KT
90890-85505Quick gasket

YAMAHA Bond No. 1215
This sealant (Bond) is used for crankcase mating sur-
face, etc.ACC-QUICK-GS-KT 90890-85505
YM-01495, 90890-01495 Drive gear holder
This tool is used when removing or tightening the pri-
mary drive gear securing nut.YM-01495 90890-01495
Part number Tool name/How to use Illustration
5PA10360

1 - 9
GEN
INFO
CONTROL FUNCTIONS
EC150000
CONTROL FUNCTIONS
ENGINE STOP SWITCH
The engine stop switch 1 is located on the left
handlebar. Continue pushing the engine stop
switch till the engine comes to a stop.
5PA10420
EC152000
CLUTCH LEVER
The clutch lever 1 is located on the left han-
dlebar; it disengages or engages the clutch.
Pull the clutch lever to the handlebar to disen-
gage the clutch, and release the lever to
engage the clutch. The lever should be pulled
rapidly and released slowly for smooth starts.
5PA10430
EC153000
SHIFT PEDAL
The gear ratios of the constant-mesh 6 speed
transmission are ideally spaced. The gears
can be shifted by using the shift pedal 1 on
the left side of the engine.
5PA10440
KICKSTARTER CRANK
Rotate the kickstarter crank 1 away from the
engine. Push the starter down lightly with your
foot until the gears engage, then kick smoothly
and forcefully to start the engine. This model
has a primary kickstarter crank so the engine
can be started in any gear if the clutch is disen-
gaged. In normal practices, however, shift to
neutral before starting.
5PA10450
EC155001
THROTTLE GRIP
The throttle grip 1 is located on the right han-
dlebar; it accelerates or decelerates the
engine. For acceleration, turn the grip toward
you; for deceleration, turn it away from you.
5PA10460

SPEC
2 - 2
GENERAL SPECIFICATIONS
Fuel:
Type Premium unleaded gasoline only with a
research octane number of 95 or higher.
(Except for ZA)
Premium gasoline (For ZA)
Tank capacity 5.0 L (1.10 Imp gal, 1.32 US gal)
Carburetor:
Type/manufacturer PWK28/KEIHIN
Spark plug:
Type/manufacturer BR10EG/NGK (resistance type)
Gap 0.5 ~ 0.6 mm (0.020 ~ 0.024 in)
Clutch type: Wet, multiple-disc
Transmission: YZ85 YZ85LW
Primary reduction system Gear←
Primary reduction ratio 65/18 (3.611)←
Secondary reduction system Chain drive←
Secondary reduction ratio 47/14 (3.357) 52/14 (3.714)
(USA, S, NZ, ZA)
48/14 (3.429)
(F, D, I, GB, E, CDN,
AUS)
Transmission type Constant mesh,
6-speed←
Operation Left foot operation←
Gear ratio: 1st 27/11 (2.454)←
2nd 32/17 (1.882)←
3rd 26/17 (1.529)←
4th 22/17 (1.294)←
5th 26/23 (1.130)←
6th 25/25 (1.000)←
Chassis: YZ85 YZ85LW
Frame type Semi double cradle←
Caster angle 26.3°26.9°
Trail 88 mm (3.46 in) 105.5 mm (4.15 in)
Tire: YZ85 YZ85LW
Type With tube←
Size (front) 70/100-17 40M 70/100-19 42M
Size (rear) 90/100-14 49M 90/100-16 52M
Tire pressure (front and rear) 100 kPa
(1.0 kgf/cm
2, 15 psi)←
Brake:
Front brake type Single disc brake
Operation Right hand operation
Rear brake type Single disc brake
Operation Right foot operation

2

SPEC
2 - 5
MAINTENANCE SPECIFICATIONS
Crankshaft:
Crank width “A”44.90 ~ 44.95 mm
(1.768 ~ 1.770 in)----
Runout limit “C”0.03 mm (0.0012 in) 0.08 mm
(0.003 in)
Big end side clearance “D”0.20 ~ 0.70 mm
(0.008 ~ 0.028 in)----
Small end free play “F”0.5 ~ 1.2 mm
(0.020 ~ 0.047 in)2.0 mm
(0.08 in)
Clutch:
Friction plate thickness 2.9 ~ 3.1 mm
(0.114 ~ 0.122 in)2.7 mm
(0.106 in)
Quantity 7 ----
Clutch plate thickness 1.8 ~ 2.2 mm (0.071 ~ 0.087 in) ----
Quantity 6 ----
Warp limit ---- 0.1 mm
(0.004 in)
Clutch spring free length 34.0 mm (1.34 in) 32.0 mm
(1.26 in)
Quantity 5 ----
Clutch housing thrust clearance 0.10 ~ 0.35 mm
(0.0039 ~ 0.0138 in)----
Clutch housing radial clearance 0.022 ~ 0.051 mm
(0.0009 ~ 0.0020 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 mesh type ----
Carburetor:
Type/manufacturer PWK28/KEIHIN ----
I. D. mark 5PA1 00 ----
Main jet (M.J) #138 ----
Jet needle-clip position (J.N) NBKF-2 ----
Main nozzle (N.J)ø3.4 ----
Cutaway (C.A) 3.0 ----
Pilot jet (P.J) #45 ----
Pilot air screw (example) (P.A.S) 2 ----
Starter jet (G.S) #62 ----
Float height (F.H) 18 ~ 20 mm (0.71 ~ 0.79 in) ----Item Standard Limit

SPEC
2 - 7
MAINTENANCE SPECIFICATIONS
Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb
Spark plug M14 × 1.25 1 20 2.0 14
Cylinder head (nut) M8 × 1.25 4 30 3.0 22
(stud bolt) M8 × 1.25 4 13 1.3 9.4
Cylinder (nut) M8 × 1.25 4 28 2.8 20
(stud bolt) M8 × 1.25 4 13 1.3 9.4
Impeller M8 × 1.25 1 14 1.4 10
Coolant drain bolt M6 × 1.0 1 10 1.0 7.2
Water pump housing M6 × 1.0 2 10 1.0 7.2
Air filter element M6 × 1.0 1 2 0.2 1.4
Carburetor joint M6 × 1.0 4 8 0.8 5.8
Reed valve M3 × 0.5 4 1 0.1 0.7
Exhaust pipe M6 × 1.0 2 12 1.2 8.7
Exhaust pipe stay M6 × 1.0 1 12 1.2 8.7
Silencer M6 × 1.0 1 12 1.2 8.7
Fiber (silencer) M6 × 1.0 2 12 1.2 8.7
Crankcase M6 × 1.0 11 8 0.8 5.8
Left crankcase cover M6 × 1.0 4 5 0.5 3.6
Right crankcase cover M6 × 1.0 4 10 1.0 7.2
Right crankcase cover M6 × 1.0 1 10 1.0 7.2
Clutch cover M6 × 1.0 6 10 1.0 7.2
Transmission oil drain bolt M8 × 1.25 1 10 1.0 7.2
Kickstarter crank M6 × 1.0 1 10 1.0 7.2
Primary drive gear M12 × 1.0 1 79 7.9 57
Clutch boss M12 × 1.0 1 70 7.0 50
Clutch spring M5 × 0.8 5 6 0.6 4.3
Drive sprocket M16 × 1.0 1 60 6.0 43
Crankcase bearing stopper M6 × 1.0 2 8 0.8 5.8
Crankcase oil seal holder M8 × 1.25 1 20 2.0 14
Shift pedal M6 × 1.0 1 10 1.0 7.2

SPEC
2 - 9
MAINTENANCE SPECIFICATIONS
Wheel:
Front wheel type Spoke wheel ----
Rear wheel type Spoke wheel ----
Front rim size/material 17 × 1.40/Aluminum ----
Rear rim size/material 14 × 1.60/Aluminum ----
Rim runout limit:
Radial ---- 2.0 mm (0.08 in)
Lateral ---- 2.0 mm (0.08 in)
Drive chain:
Type/manufacturer DID428DS/DAIDO ----
Number of links 117 links + joint ----
Chain slack 35 ~ 45 mm (1.4 ~ 1.8 in) ----
Chain length (10 links) ---- 122.1 mm (4.81 in)
Front disc brake:
Disc outside dia. × Thickness 220 × 3.0 mm (8.66 × 0.12 in) 220 × 2.5 mm
(8.66 × 0.10 in)
Deflection limit ---- 0.15 mm (0.006 in)
Pad thickness 4.0 mm (0.16 in) 0.8 mm (0.03 in)
Master cylinder inside dia. 11.0 mm (0.433 in) ----
Caliper cylinder inside dia. 22.22 mm (0.875 in) × 2 ----
Brake fluid type DOT #4 ----
Rear disc brake:
Disc outside dia. × Thickness 190 × 3.0 mm (7.84 × 0.12 in) 190 × 2.5 mm
(7.84 × 0.12 in)
Deflection limit ---- 0.15 mm (0.006 in)
Pad thickness 3.7 mm (0.15 in) 1.0 mm (0.04 in)
Master cylinder inside dia. 12.7 mm (0.500 in) ----
Caliper cylinder inside dia. 27.0 mm (1.063 in) × 1 ----
Brake fluid type DOT #4 ----
Brake lever and brake pedal:
Brake lever position 95 mm (3.74 in) ----
Brake pedal height
(vertical height above footrest top)4 ~ 10 mm (0.16 ~ 0.39 in) ----
Clutch lever free play (lever end) 10 ~ 15 mm (0.39 ~ 0.59 in) ----
Throttle grip free play 3 ~ 5 mm (0.12 ~ 0.20 in) ----Item Standard Limit