2004 YAMAHA YZ85 engine removal

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

4 - 1
ENG
EC400000
ENGINE
SEAT, FUEL TANK AND SIDE COVERS
5PA40010
Extent of removal:
1 Seat removal
2 Fuel tank removal
3 Side covers removal
4 Number plate removal
Extent of removal Order Part name Q’ty Remarks
Preparation for removalSEAT, FUEL TANK AND SIDE
COVERS REMOVAL
Turn the fuel cock to “OFF”.
Disconnect the fuel hose.
1Seat 1
2 Air scoop 1
3 Bolt (fuel tank) 2
4 Fuel tank 1
5 Left side cover 1
6 Right side cover 1
7 Number plate 1
13
4
2
3
SEAT, FUEL TANK AND SIDE COVERS

4 - 26
ENGCLUTCH AND PRIMARY DRIVEN GEAR
EC490000
CLUTCH AND PRIMARY DRIVEN GEAR
EC498000
CLUTCH PLATE AND FRICTION PLATE
5PA40720
Extent of removal:
1 Clutch plate and friction plate removal
Extent of removal Order Part name Q’ty Remarks
CLUTCH PLATE AND FRIC-
TION PLATE REMOVAL
Preparation for removal Drain the transmission oil. Refer to “TRANSMISSION OIL
REPLACEMENT” section in the CHAP-
TER 3.
Clutch cable Disconnect at engine side.
1 Clutch cover 1
2 Bolt (clutch spring) 5
3 Clutch spring 5
4 Pressure plate 1
5 Friction plate 7
6 Clutch plate 6
1

4 - 49
ENG
EC4M0000
ENGINE REMOVAL
5PA41490
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.
Drain the coolant. Refer to “COOLANT REPLACEMENT”
section in the CHAPTER 3.
Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Carburetor Refer to “CARBURETOR AND REED
VALVE” section.
Exhaust pipe and silencer Refer to “EXHAUST PIPE AND
SILENCER” section.
Clutch cable Disconnect at engine side.
Radiator hose 1 Disconnect at cylinder head side.
Radiator hose 2 Disconnect at water pump side.
Spark plug cap
Disconnect the CDI magneto
lead.
ENGINE REMOVAL

4 - 50
ENG
5PA41490
Extent of removal:
1 Engine removal
Extent of removal Order Part name Q’ty Remarks
1 Left crankcase cover 1
2 Nut (drive sprocket) 1
Refer to “REMOVAL POINTS”. 3 Lock washer 1
4 Drive sprocket 1
5 Engine mounting bolt 2
6 Pivot shaft 1
Refer to “REMOVAL POINTS”.
7Engine 1
1
ENGINE REMOVAL

4 - 51
ENG
EC4M3000
REMOVAL POINTS
EC4F3100
Drive sprocket
1. Remove:

Nut (drive sprocket) 1

Lock washer 2
NOTE:

Straighten the lock washer tab.

Loosen the nut while applying the rear brake.5PA41510
2. Remove:

Drive sprocket 1

Drive chain 2
NOTE:
Remove the drive sprocket together with the
drive chain.
5PA41520
EC4M3301
Engine removal
1. Remove:

Pivot shaft 1
NOTE:
If the pivot shaft is pulled all the way out, the
swingarm will come loose. If possible, insert a
shaft of similar diameter into the other side of
the swingarm to support it.5PA41530
2. Remove:

Engine 1
From right side.
NOTE:
Make sure that the couplers, hoses and cables
are disconnected.
5PA41540
ENGINE REMOVAL

4 - 52
ENG
EC4M5000
ASSEMBLY AND INSTALLATION
Engine installation
1. Install:

Engine 1
Install the engine from right side.

Pivot shaft 2

Engine mounting bolt (front) 3

Engine mounting bolt (lower) 4
NOTE:
Apply the molybdenum disulfide grease on the
pivot shaft.
5PA41550
T R..63 Nm (6.3 m · kg, 45 ft · lb)
T R..69 Nm (6.9 m · kg, 50 ft · lb)
T R..69 Nm (6.9 m · kg, 50 ft · lb)
Drive sprocket
1. Install:

Drive sprocket 1

Drive chain 2
NOTE:
Install the drive sprocket together with the
drive chain.
5PA41560
2. Install:

Lock washer 1

Nut (drive sprocket) 2
NOTE:
Tighten the nut while applying the rear brake.
3. Bend the lock washer tab to lock the nut.
5PA41570
T R..60 Nm (6.0 m · kg, 43 ft · lb)
4. Install:

Gasket (left crankcase cover)

Left crankcase cover 1

Screw (left crankcase cover) 2
NOTE:
Tighten the screws in stage, using a crisscross
pattern.
5PA41580
T R..5 Nm (0.5 m · kg, 3.6 ft · lb)
ENGINE REMOVAL

4 - 53
ENG
CRANKCASE AND CRANKSHAFT
5PAR0009
Extent of removal:
1 Crankcase separation
2 Crankshaft removal
3 Crankshaft bearing removal
Extent of removal Order Part name Q’ty Remarks
CRANKCASE AND CRANK-
SHAFT REMOVAL
Preparation for removal Engine Refer to “ENGINE REMOVAL” section.
Piston Refer to “CYLINDER HEAD, CYLINDER
AND PISTON” section.
Primary drive gear
Refer to “KICK SHAFT, SHIFT SHAFT
AND PRIMARY DRIVE GEAR” section. Kick idle gear
Stopper lever assembly
Rotor and stator Refer to “CDI MAGNETO” section.
1 Screw (crankcase) 11
2 Crankcase oil seal holder 1
3 Right crankcase 1
Use special tool.
Refer to “REMOVAL POINTS”.
4 Left crankcase 1
5 Crankshaft 1 Use special tool.
Refer to “REMOVAL POINTS”.
6 Oil seal 2
7 Bearing 2 Refer to “REMOVAL POINTS”.
2
1
3
CRANKCASE AND CRANKSHAFT