2008 Sportsman 500 Service Manual Chapter 3

ENGINE

CHAPTER 3

ENGINE

SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3

TORQUE SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3

SPECIAL TOOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3

ENGINE FASTENER TORQUE PATTERNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3

ENGINE SERVICE DATA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4

ENGINE SERVICE DATA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5

GENERAL ENGINE SERVICE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6

PISTON IDENTIFICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6

COOLING SYSTEM SPECIFICATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6

COOLING SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7

ACCESSIBLE COMPONENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8

ENGINE REMOVAL (TYPICAL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8

ENGINE INSTALLATION NOTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9

CYLINDER HONE SELECTION/ HONING PROCEDURE. . . . . . . . . . . . . . . . . . . . . . . . 3.9

HONING TO OVERSIZE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9

CLEANING THE CYLINDER AFTER HONING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.10

CRANKSHAFT STRAIGHTENING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.10

ENGINE LUBRICATION- EH 50PL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.11

OIL PRESSURE TEST - EH 50PL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.11

OIL PUMP PRIMING PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.11

OIL FLOW - EH50PL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.11

EH50PL OIL FLOW DIAGRAM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.12

EH50PL ENGINE EXPLODED VIEWS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.13

ENGINE DISASSEMBLY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.14

CAM CHAIN TENSIONER/ROCKER ARM/ CAMSHAFT REMOVAL . . . . . . . . . . . . . . 3.14

CAM CHAIN TENSIONER INSPECTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.14

ROCKER ARM/SHAFT INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.15

CAMSHAFT REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.16

AUTOMATIC COMPRESSION RELEASE REMOVAL/INSPECTION . . . . . . . . . . . . . . 3.17

AUTOMATIC COMPRESSION RELEASE INSTALLATION. . . . . . . . . . . . . . . . . . . . . . 3.18

CAMSHAFT INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.18

CYLINDER HEAD REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.19

CYLINDER HEAD EXPLODED VIEW, EH50PL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.20

CYLINDER HEAD INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.21

CYLINDER HEAD WARP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.21

CYLINDER HEAD DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.21

VALVE INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.22

COMBUSTION CHAMBER. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.23

VALVE SEAT RECONDITIONING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.23

CYLINDER HEAD ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.26

VALVE SEALING TEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.26

VALVE CLEARANCE ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.26

CYLINDER/PISTON REMOVAL AND INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.27

PISTON REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.28

CYLINDER INSPECTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.28

PISTON-TO-CYLINDER CLEARANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.29

PISTON/ROD INSPECTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.29

PISTON RING INSTALLED GAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.30

CRANKCASE DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.30

STARTER DRIVE REMOVAL/INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.31

FLYWHEEL/STATOR REMOVAL/INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.31

CAM CHAIN/TENSIONER BLADE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.32

ONE WAY VALVE REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.32

CRANKCASE SEPARATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.33

3

3.1

ENGINE

OIL PUMP REMOVAL/INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.33

OIL PUMP ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.34

COUNTER BALANCER SHAFT REMOVAL/INSPECTION . . . . . . . . . . . . . . . . . . . . . . 3.34

CRANKSHAFT REMOVAL/INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.35

CRANKCASE BEARING INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.36

PUMP SHAFT OIL SEAL/WATER PUMP MECHANICAL SEAL REMOVAL. . . . . . . . . 3.36

CRANKCASE INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.36

BEARING INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.37

END PLAY INSPECTION/ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.37

CRANKSHAFT END PLAY ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.37

COUNTER BALANCER SHAFT END PLAY ADJUSTMENT. . . . . . . . . . . . . . . . . . . . . 3.38

OIL PUMP SHAFT END PLAY ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.39

ENGINE REASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.40

PUMP SHAFT OIL SEAL INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.40

CRANKSHAFT/COUNTER BALANCE/OIL PUMP INSTALLATION . . . . . . . . . . . . . . . 3.40

CRANKCASE ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.41

WATER PUMP MECHANICAL SEAL INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . 3.41

WATER PUMP MECHANICAL SEAL REMOVAL - ENGINE INSTALLED . . . . . . . . . . 3.41

ONE WAY VALVE INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.42

CAM CHAIN DRIVE SPROCKET INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.43

TENSIONER BLADE INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.43

PISTON RING INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.43

PISTON INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.44

CYLINDER INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.44

CYLINDER HEAD INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.45

CAM CHAIN/CAMSHAFT INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.45

CAMSHAFT TIMING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.46

CAMSHAFT TIMING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.48

CAM CHAIN TENSIONER INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.49

STATOR, FLYWHEEL AND STARTER DRIVE INSTALLATION. . . . . . . . . . . . . . . . . . 3.49

ROCKER SHAFT/ROCKER ARM ASSEMBLY INSTALLATION . . . . . . . . . . . . . . . . . . 3.50

THERMOSTAT INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.50

OIL PIPES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.50

RECOIL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.51

RECOIL DISASSEMBLY/INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.51

RECOIL ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.52

TROUBLESHOOTING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.53

SPARK PLUG FOULING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.53

ENGINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.53

COOLING SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.54

3.2

SPECIFICATIONS

Torque Specifications

TORQUE SPECIFICATIONS

Fastener

Blind Plug (Oil

Pressure)

Camshaft Sprocket

Camshaft Chain

Tensioner Lever

Camshaft Chain

Tensioner

Camshaft Chain

Tensioner Cap

Carburetor Adaptor

Crankcase

Crankshaft Slotted Nut

(Cam Chain Drive

Sprocket)

Cylinder Base Bolts

Size

1/8 PT

(28tpi)

6mm

6mm

6mm

11mm

8mm

8mm

28mm

EH50PLE

Ft. Lbs. (Nm)

6.5-11 (9-15 Nm)

5-6.5 (7-9 Nm)

5-6.5 (7-9 Nm)

5-6.5 (7-9 Nm)

14-19 (20-25 Nm)

12-14 (16-20 Nm)

14-15 (19-21 Nm)

35-51 (47-69 Nm)

Cylinder Head Bolts

10mm

6mm

11mm

6mm

Drive Clutch Bolt

Flywheel

Oil Delivery Pipe

Oil Drain Bolt

(Crankcase)

Oil Filter Pipe Fitting

7/16 - 20

16mm

12mm

14mm

20mm

Oil Hose Fitting 1/8 Pipe

Thread

N/A Hard Metal Oil Line

Banjo Fitting

Oil Pump

Oil Pump Case Screw

One Way Valve

Recoil Housing

Rocker Cover

Rocker Support

6mm

5mm

11mm

6mm

Rocker Adjuster Screw 6mm

Water Pump Impeller

Nut

6mm

Water Pump Housing

Cover

Stator Plate

6mm

8mm

6mm

6mm

Starter Motor

Spark Plug

Thermistor

6mm

14mm

--

45-49 (61-67 Nm)

6-8 (9-11 Nm)

Refer to Engine

Assembly for torque procedure

40 (55 Nm)

58-72 (78-98 Nm)

11-15 (15-21 Nm)

14-17 (19-23 Nm)

36-43 (49-59 Nm)

6.5-11 (9-15 Nm)

11-16 ft.lbs. (15-21

Nm)

5-6.5 (7-9 Nm)

1.5-2 (2-3 Nm)

14-19 (20-25 Nm)

5-6.5 (7-9 Nm)

7-8 (9-11 Nm)

8-10 (11-13 Nm)

6-7 (8-10 Nm)

5-6.5 (7-9 Nm)

5-6.5 (7-9 Nm)

5-6.5 (7-9 Nm)

5-6.5 (7-9 Nm)

9-11 (12-15 Nm)

26 ± 2.1 (35 ± 3 Nm)

ENGINE

Special Tools

PART NUMBER

2200634

2870390

2871043

2871283

5131135

2870569

2870975

PV-43527

TOOL DESCRIPTION

Valve Seat Reconditioning

Kit

Piston Support Block

Flywheel Puller

Crankshaft/Water Pump

Seal Install Kit

Water Pump Install Kit

Crankshaft Truing Stand

Mity Vac™ Pressure Test

Tool

OIl Filter Wrench

Engine Fastener Torque Patterns

Tighten cylinder head, cylinder base, and crankcase fasteners in

3 steps following the sequence outlined.

6mm

3

2

5

3

1

4

Cylinder Head

Cylinder Base

Pattern

5

9

6

7

10

1

3

8

2

6

4

Crankcase

Pattern

3.3

ENGINE

Engine Service Data

Cylinder Head / Valve

EH50PLE

Rocker Arm

Camshaft

Rocker arm ID

Rocker shaft OD

Rocker shaft Oil Clearance Std

Cam lobe height In

Ex

.8669-.8678" (22.020-22.041 mm)

.8656-.8661" (21.987-22.0 mm)

.0008-.0021" (.020-.054 mm)

Limit .0039" (.10 mm)

Std 1.2884-1.2924” (32.726-32.826 mm)

Limit 1.2766" (32.426 mm)

Std 1.2884-1.2924” (32.726-32.826 mm)

Limit 1.2766" (32.426 mm)

Camshaft journal OD Mag 1.4935-1.4941” (37.935-37.950 mm)

PTO 1.4935-1.4941” (37.935-37.950 mm)

Camshaft journal bore ID Mag 1.4963-1.4970” (38.005-38.025 mm)

Camshaft Oil clearance

PTO 1.4963-1.4970” (38.005-38.025 mm)

Std .022-.0035”(.055-.090 mm)

Limit .0039" (.10 mm)

Cylinder Head Surface warpage limit

Standard Height

Valve Seat Contacting width In

Valve Guide

Valve

Inner diameter

Ex

Protrusion above head

Margin Thickness In

Ex

.0020" (.05 mm)

3.870" (98.3 mm)

.028" (.7 mm) Std

Limit .055" (1.4 mm)

Std .039" (1.0 mm)

Limit .071" (1.8 mm)

.2362-.2367" (6.0-6.012 mm)

.689-.709" (17.5-18.0 mm)

.039" (1.0 mm) Std

Limit .031" (.8 mm)

Std .047" (1.2 mm)

Limit .031" (.8 mm)

Valve

Valve Spring

Stem diameter

Stem Oil Clearance Std

Overall length

Overall Length

Squareness

Limit

In

Ex

In

Ex

.2343-.2348" (5.950-5.965 mm)

.2341-.2346" (5.945-5.960 mm)

.0014-.0024" (.035-.062 mm)

In

Ex

.0016-.0026" (.040-.067 mm)

.0059" (.15 mm)

3.976" (101.0 mm)

3.984" (101.2 mm)

Std 1.654" (42.0 mm)

Limit 1.575" (40.0 mm)

.075” (1.9 mm)

3.4

ENGINE

Engine Service Data

Cylinder / Piston / Connecting Rod

Cylinder

EH50PLE

Surface warpage limit (mating with cylinder head)

.0020” (0.05 mm)

Cylinder bore Std 3.6221-3.6228” (92.00-92.02 mm)

Piston

Taper limit

Out of round limit

Piston clearance

Boring Limit

Outer diameter

.0020” (0.05 mm)

.0020” (0.05 mm)

.0006-.0018" (0.015-0.045 mm) Std

Limit .0024” (0.060 mm)

.020” (.5 mm)

Std 3.6204-3.6215” (91.970-91.985mm)

.0098" (.25 mm) OS 3.6304-3.6310” (92.21-92.23 mm)

.0197" (.50 mm) OS 3.6403-3.6407” (92.46-92.47 mm)

Standard inner diameter of piston pin bore .9055-.9057” (23.0-23.006 mm)

Piston Pin Outer diameter .9053-.9055” (22.994-23.0 mm)

Standard clearance-piston pin to pin bore .0002-.0003” (.004-.008 mm)

Degree of fit

Piston Ring Piston Ring Installed gap

Top ring Std

Limit

Piston Pin must be a push (by hand) fit at 68 o

F (20 o

.0079-.0138" (.20-.36 mm)

.039” (1.0 mm)

Second ring

Std

Limit

Oil ring Std

Limit

Piston Ring Standard clearance - piston ring to ring groove

Top ring Std

Limit

Second ring

Std

Limit

Connecting Connecting rod small end ID

Rod

Connecting rod small end radial clearance

Std

Limit

Connecting rod big end side clearance

Std

Limit

Connecting rod big end radial clearance

Std

Limit

Crankshaft Crankshaft runout limit

.0079-.0138" (.20-.36 mm)

.039” (1.0 mm)

.0079-.0276" (0.20-0.70 mm)

.059" (1.5 mm)

.0016-.0031" (0.040.-080 mm)

.0059" (.15 mm)

.0012-.0028" (0.030-0.070 mm)

.0059" (.15 mm)

.9058- .9063” (23.007 - 23.020 mm)

.0003-.0010” (.007-.026 mm)

.0020 (.05 mm)

.0039-.0256” (.1-.65 mm)

.0315” (.80 mm)

.0004-.0015” (.011-.038 mm)

.0020” (.05 mm)

.0024” (.06 mm)

KEY - Std: Standard; OS: Oversize; ID: Inner Diameter; OD: Outer Diameter; Mag: Magneto Side;

PTO: Power Take Off.

3

3.5

ENGINE

GENERAL ENGINE SERVICE

Piston Identification

The piston may have an identification mark or the piston may not have an identification mark for piston placement. If the piston has an identification mark, follow the directions for piston placement below. If the piston does not have an identification mark, the direction for placement of the piston does not matter.

Note the directional and identification marks when viewing the pistons from the top. The letter “F”, “

J

”,“

X

” or : must always be toward the flywheel side of the engine. The other numbers are used for identification as to diameter, length and design. Four stroke engine rings are rectangular profile. See text for oil control ring upper rail installation. Use the information below to identify pistons and rings.

Engine

Model No.

EH50PLE

EH42PLE

Oversize

Available* (mm)

Piston

Length

.25

.50

.25

.50

72 mm

66 mm

Standard

Piston

Identification

C

B

*Pistons and rings marked 25 equal .25mm (.010”) oversized

*Pistons and rings marked 50 equal .50mm (.020”) oversized

Cooling System Specifications

Sensor

18.5 + ft. lbs.

(25 Nm)

THERMISTOR READING DURING OPERATION

Condition

Temperature

System

Capacity

Radiator Cap

Relief

Pressure

Approx. Reading

(Min-Max)

37.3 - 39.2 k

Ω

Temperature

68° F (20° C)

2.25 Quarts

(2.13L)

13 PSI (89.6 kpa)

3.6

Cooling System

WARNING

Never remove radiator cap when engine is warm or hot.

The cooling system is under pressure and serious burns may result. Allow the engine and cooling system to cool before servicing.

FLOW

Radiator

ENGINE

System Pressure Test

1.

Remove radiator cap cover located in storage box.

2.

Remove recovery bottle hose from coolant filler.

3.

Connect a Mity Vac™ (PN 2870975) to radiator and pressurize system to 10 PSI (68.9 kpa). The system must retain 10 lbs of pressure for five minutes or longer. If pressure loss is evident within five minutes, check radiator, all cooling system hoses and clamps, or water pump seal.

Radiator Cap Pressure Test

1.

Remove radiator cap and test using a cap tester

(commercially available).

2.

The radiator cap relief pressure is 13 lbs (89.6 kpa).

3

Thermostat

Water Pump

Fan

Cylinder

Head

Cylinder

Upper Hose

Radiator

Lower Hose

Filler Neck

Overflow Bottle

Top

Bottom

Radiator

Left Side

View

Radiator

Front

View

3.7

ENGINE

RECOMMENDED COOLANT

Use only high quality antifreeze/coolant mixed with distilled water in a 50/50 or 60/40 ratio, depending on freeze protection required in your area..

CAUTION

Using tap water in the cooling system will lead to a buildup of deposits which may restrict coolant flow and reduce heat dissipation, resulting in possible engine damage. Polaris Premium 60/40 Antifreeze/

Coolant is recommended for use in all cooling systems, and comes pre-mixed, ready to use.

Accessible Components

The following components can be serviced or removed with the engine installed in the frame:

• Flywheel

• Alternator/Stator

• Starter Motor/Starter Drive

• Cylinder Head

• Cylinder

• Piston/RIngs

• Camshaft

• Rocker Arms

• Cam Chain and Sprockets

• Water Pump / Water Pump Mechanical Seal*

The following components require engine removal for service:

• Oil pump / Oil Pump Drive Gear

• Counterbalance Shaft or Bearing(s)

• Connecting Rod

• Crankshaft

• Crankshaft Main Bearings

• Crankcase

*It may be necessary to loosen engine mounts and move engine slightly to access water pump. Use the Water

Pump Mechanical Seal Puller (PN 2872105) to replace mechanical seal with engine in frame.

Engine Removal (TYPICAL)

1.

Clean work area.

2.

Thoroughly clean the ATV engine and chassis.

3.

Disconnect battery negative(-) cable.

4.

Remove the following parts as required.

• Seat

• Left and Right Side Covers (Refer to Chapter 5)

• Fuel Tank Cover / Front Cab (Refer to Chapter 5)

• Fuel Tank (Refer to Chapter 4)

5.

Disconnect spark plug high tension lead.

6.

Remove springs from exhaust pipe and remove pipe.

7.

Drain coolant and engine oil.

8.

Remove air pre-cleaner and duct.

9.

Remove airbox.

10. Remove carburetor. Insert a shop towel into the carburetor flange to prevent dirt from entering the intake port.

11. Remove center chain guard on chain drive AWD models.

12. Remove center drive and driven sprocket bolts and remove chain and sprockets as an assembly.

13. Refer to PVT System to remove outer clutch cover, drive belt, drive clutch, driven clutch, and inner cover.

14. Starter motor. Note ground cable location. Mark positive

(+) cable mounting angle and remove cable.

15. Remove transmission linkage rod(s) from gear selector and secure out of the way.

16. Disconnect coolant temperature sensor wire.

17. Remove engine to chassis ground cable.

18. Remove all engine mount nuts and / or engine mount plates.

19. Remove engine through right side of frame.

3.8

ENGINE

Engine Installation Notes

After the engine is installed in the frame, review this checklist and perform all steps that apply.

General Items

1.

Install previously removed components using new gaskets, seals, and fasteners where applicable.

2.

Perform regular checks on fluid levels, controls, and all important areas on the vehicle as outlined in the daily preride inspection checklist (refer to Chapter 2 or the Owner’s

Safety and Maintenance Manual).

PVT System

1.

Adjust center distance of drive and driven clutch. (Chapter

6)

2.

Adjust clutch offset, alignment, and belt deflection.

(Chapter 6)

3.

Clean clutch sheaves thoroughly and inspect inlet and outlet ducts for proper routing and sealing. (Chapter 6)

Transmission

1.

Inspect transmission operation and adjust linkage if necessary. Refer to Chapter 2 and Chapter 8.

Exhaust

1.

Replace exhaust gaskets. Seal connections with high temp silicone sealant if required.

2.

Check to be sure all springs are in good condition.

Bleed Cooling System

1.

Remove radiator cap and slowly add coolant to top of filler neck.

2.

Fill coolant reservoir tank to full mark.

3.

Install radiator cap and squeeze coolant lines to force air out of system.

4.

Again remove radiator cap and slowly add coolant to top of fill neck.

5.

Start engine and observe coolant level in the radiator. Allow air to purge and top off as necessary. Reinstall radiator cap and bring engine to operating temp. Check level in reservoir tank after engine is cool and add coolant if necessary.

Engine Break In Period

4 Cycle Engine Break-In Period is defined as the first 10 hours of engine operation or 2 full tanks of fuel.

1.

Use only Polaris Premium 4 All Season synthetic oil, or

API certified “SH” oil.Never substitute or mix oil brands.

Serious engine damage can result.

2.

Use fuel with a minimum octane of 87 (R+M)/2 method.

3.

Change break-in oil and filter at 20 hours or 500 miles, whichever comes first.

Cylinder Hone Selection/ Honing Procedure

CAUTION

Selecting a hone which will straighten as well as remove material from the cylinder is very important.

Using a common spring loaded finger type glaze breaker for honing is never advised. Polaris recommends using a rigid hone or arbor honing machine which also has the capability of oversizing.

Cylinders may be wet or dry honed depending upon the hone manufacturer’s recommendations. Wet honing removes more material faster and leaves a more distinct pattern in the bore.

NOTE: See next page for more information on honing.

Honing To Oversize

3

CAUTION

If cylinder wear or damage is excessive, it will be necessary to oversize the cylinder using a new oversize piston and rings. This may be accomplished by either boring the cylinder and then finish honing to the final bore size, or by rough honing followed by finish honing.

CAUTION

For oversize honing, always wet hone using honing oil and a coarse roughing stone. Measure the piston (see piston measurement) and rough hone to the size of the piston. Always leave .002 - .003" (.05 - .07 mm) for finish honing. Refer to piston-to-cylinder clearance specifications before honing. Complete the sizing with fine grit stones to provide the proper cross-hatch finish and required piston clearance.

EXAMPLE OF CROSS HATCH PATTERN

3.9

ENGINE

A finished cylinder should have a cross-hatch pattern to ensure piston ring seating and to aid in the retention of the fuel/oil mixture during initial break in. Hone cylinder according to hone manufacturer’s instructions, or these guidelines:

• Use a motor speed of approximately 300-500

RPM, run the hone in and out of the cylinder rapidly until cutting tension decreases. Remember to keep the hone drive shaft centered (or cylinder centered on arbor) and to bring the stones approximately 1/2” (1.3 cm) above and below the bore at the end of each stroke.

• Release the hone at regular intervals and inspect the bore to determine if it has been cleared, and to check piston fit. NOTE: Do not allow cylinder to heat up during honing. The thinner areas of the liner around the ports will expand causing uneven bore.

• After honing has been completed inspect all port opening areas for rough or sharp edges. Apply a slight chamfer to all ports to remove sharp edges or burrs, paying particular attention to the corners of the intake and exhaust ports.

Cleaning the Cylinder After Honing

It is very important that the cylinder be thoroughly cleaned after honing to remove all grit material. Wash the cylinder in a solvent, then in hot, soapy water. Pay close attention to areas where the cylinder sleeve meets the aluminum casting (transfer port area). Use electrical contact cleaner if necessary to clean these areas. Rinse thoroughly, dry with compressed air, and oil the bore immediately with Polaris 4 Cycle Lubricant.

Crankshaft Straightening

Lubricate the bearings and clamp the crankshaft securely in the

Crankshaft Truing Stand (PN 2870569). Refer to the illustrations below.

Crankshaft Truing Stand

(PN 2870569)

NOTE: The rod pin position in relation to the dial indicator position tells you what action is required to straighten the shaft.

HIGH .004 (.1 mm)

B

SUPPORT CRANKSHAFT HERE

1.

To correct a situation like the one shown in the illustration, strike the shaft at point A with a brass hammer.

HIGH .002 (.05 mm)

HIGH .005 (.13 mm)

A A

2.

To correct a situation like the one shown in the illustration, squeeze the crankshaft at points A. (Use tool from alignment kit).

HIGH .002 (.05 mm)

A

A

HIGH .005 (.13 mm)

3.10

3.

If the crank rod pin location is 180 o

from the dial indicator

(opposite that shown above), it will be necessary to spread the crankshaft at position A as shown in the illustration at right. When rebuilding and straightening a crankshaft, runout must be as close to zero as possible.

NOTE: Maximum allowable runout is .0024”.

Engine Lubrication- EH 50PL

Oil Type:Polaris Premium 4 Synthetic or API certified “SH”

2W-50 oil

Capacity:. . . . . . . . Approximately 2 U.S. Quarts (1.9 l)

Filter Wrench . . . . (PV-43527)

*Drain Plug / Screen Fitting...14 ft. lbs. (19 Nm) (If fitting is removed, follow oil pump priming procedure).

*Oil Pressure Specification...20 PSI @ 5500 RPM, Polaris

2W-50 Synthetic (Engine Hot)

Oil Pressure Test - EH 50PL

1.

Remove blind plug on front left cylinder head.

2.

Insert a 1/8 NPT oil pressure gauge adaptor into the cylinder head and attach the gauge.

3.

Start engine and allow it to reach operating temperature, monitoring gauge indicator.

NOTE: Use only Polaris Premium 4 Synthetic Engine

Lubricant (PN 2871281).

Oil Pressure at 5500 RPM (Engine Hot):

Standard: 20 PSI

Minimum: 12 PSI

Oil Pump Priming Procedure

See “Oil Pump Priming Procedure” on page 2.25.

ENGINE

Oil Flow - EH50PL

The following chart describes the flow of oil through the

EH50PL engine. Beginning at the oil tank, the oil flows through a screen fitting in the bottom of the tank and into the oil supply hose. The feed side of the oil pump draws oil through the hose and into the crankcase oil gallery, and then pumps the oil through another passage to the one way valve. (When the engine is off, the one way valve closes to prevent oil in the tank from draining into the crankcase.) The oil is pumped through a delivery pipe to the oil filter. If the oil filter is obstructed, a bypass valve contained in the filter allows oil to bypass the filter element.

At this point, the oil is diverted in two directions. Oil is supplied to the camshaft through the left front cylinder stud, and an oil passage in the head. Oil enters the camshaft through the PTO (L) journal. The camshaft journals, cam lobes, and rocker arms are lubricated through holes in the camshaft. The oil lubricates the cam chain and sprocket and drains to the sump.

The other oil path from the filter leads through a delivery pipe to the crankcase main oil gallery, which leads to the stator plate oil passage. Here it passes through the slotted friction bearing

(located in the stator plate) into the crankshaft. An oil seal on the stator plate prevents oil from entering the stator/flywheel area.

Oil travels through the crankshaft to the crank pin, lubricating the connecting rod large end bearing directly. Oil also passes through an oil jet (drilled orifice) in the end of the crank pin to the PTO end main bearings and counterbalancer gears.

Residual oil from the lubrication of the crankshaft and connecting rod indirectly lubricates the cylinder wall, piston, rings, connecting rod small end bearing, piston pin, oil/water pump drive gears, cam chain and drive sprocket, and Magneto end crankshaft main bearing.

The one-way valve is located on the front left (PTO) side of the crankcase. The valve prevents oil in the tank from draining into the engine sump when the engine is off. The valve mechanism consists of a plunger, return spring, guide plug, and sealing washer. When the engine is running, oil pressure lifts the plunger off the seat, allowing oil flow. When the engine is off, spring pressure forces the plunger against the oil passage seat, preventing oil flow from the tank to the sump. The one-way valve requires very little maintenance. If engine oil drains into the sump when the engine is off, inspect the valve sealing surface for debris or damage. Inspect the return spring for distortion or damage.

3

3.11

ENGINE

EH50PL Oil Flow Diagram

Internal passage to camshaft (front left head bolt)

Vent Hose

Oil Filter

Oil feed to filter

From filter to crankshaft

Oil Tank

Bottom fitting is oil exhaust or return to tank

One way valve

Top fitting is oil feed or intake from bottom of tank

EH50PL Oil Flow Chart

Top of Oil Tank

Oil Tank

Union Fitting

(Upper)

Union Fitting (Lower)

Oil Hose

Crankcase

Oil Gallery

Screen Fitting

(Bottom of Tank)

Oil Hose

Oil Pump

(Scavenging)

Oil Strainer

Crankcase

Crankcase

Oil Gallery

Chain Room

Sprocket

Chain

Small End

Bearing

Oil Pump

(Feed)

Prevents oil from draining into crankcase with engine off

One Way Valve

Delivery Pipe

Bypass

Oil Filter

Cam Shaft

Journal

Rocker Arm

Rocker Shaft

Cylinder Sleeve

Cam Lobe

Cam Shaft

Journal

Through Cylinder

Stud Front Left

Delivery Pipe

Delivery Pipe

Crankcase

Oil Gallery

Metal

Indirect

Lubrication

Main Bearing

(PTO)

Large End

Bearing

Crank Pin

Crankshaft

Oil

Jet

3.12

EH50PL Engine Exploded Views

Crankcase

Cylinder/

Cylinder Head

ENGINE

3

Crankshaft and Piston

Valvetrain

3.13

ENGINE

ENGINE DISASSEMBLY

Cam Chain Tensioner/ROCKER ARM/

CAMSHAFT Removal

1.

Remove ignition timing inspection plug from recoil housing.

TDC “T” Mark

NOTE: The cam lobe should be pointing down and valves should have clearance at this point.

Rotation

Advance Marks

To position crankshaft at Top Dead Center (TDC) on compression stroke:

2.

Rotate engine slowly in the direction of rotation watching intake valves open and start to close.

3.

Continue to rotate engine slowly, watching camshaft sprocket marks and the mark in the timing inspection hole.

5.

Remove cam chain tensioner plug, sealing washer, and spring.

CAUTION

The plug is under spring tension. Maintain inward pressure while removing.

6.

Remove the two 6x25 mm cam chain tensioner flange bolts.

7.

Tap lightly on tensioner body with a soft face hammer to loosen and remove tensioner.

Cam Chain Tensioner Inspection

1.

Pull cam chain tensioner plunger outward to the end of its travel. Inspect teeth on ratchet pawl (A) and plunger teeth

(B) for wear or damage.

4.

Align single (TDC) mark on flywheel with projection in inspection hole, and the cam sprocket pin (facing upward) aligned with the camshaft to crankshaft center line.

A

B

3.14

ENGINE

2.

Push ratchet pawl and hold it. The plunger should move smoothly in and out of the tensioner body.

3.

Release ratchet pawl and push inward on plunger. It should remain locked in position and not move inward.

2.

Inspect each rocker arm cam follower surface. If there is any damage or uneven wear, replace the rocker arm.

NOTE: Always inspect camshaft lobe if rocker arms are worn or damaged.

Tensioner Spring Free Length:

2.02” (5.13 cm)

Limit 1.92 (4.88cm)

4.

Measure free length of tensioner spring. Replace spring if excessively worn. Compare to specifications.

5.

Replace entire tensioner assembly if any part is worn or damaged.

Rocker Arm/Shaft Inspection

3.

Measure O.D. of rocker shaft. Inspect it for wear or damage.

Compare to specifications.

Rocker Shaft O.D.:

.8656 - .8661 (21.987-22.0 mm)

3

Rocker Arm & Support I.D.:

.8669 - .8678 (22.020-22.041 mm)

1.

Mark or tag rocker arms to keep them in order for assembly.

3.15

ENGINE

4.

Measure I.D. of each rocker arm and compare to specifications.

3.

Loosen three camshaft sprocket bolts.

4.

Remove camshaft end cap and O-Ring.

Rocker Shaft Oil Clearance:

Std: .0008 - .0021 (.020-.054 mm)

Limit: .0039” (.10 mm)

5.

Measure I.D. of both rocker arm shaft supports and visually inspect surface. Compare to specifications.

6.

Subtract rocker shaft O.D. from rocker arm & shaft support

I.D. This is the oil clearance. Compare to specifications.

7.

Inspect rocker adjuster screws for wear, pitting, or damage to threads of the adjuster or locknut. Replace all worn or damaged parts. NOTE: The end of the adjuster screw is hardened and cannot be ground or re-faced.

Camshaft Removal

1.

Remove thermostat housing.

5.

Inspect camshaft end cap (thrust face) for wear. Replace if worn or damaged.

6.

Place a clean shop towel in the area below cam chain sprocket and remove sprocket retaining bolts.

2.

Remove camshaft sprocket inspection cover.

3.16

7.

Slide camshaft inward to allow removal of cam sprocket and remove sprocket from camshaft and chain.

ENGINE

8.

Secure cam chain with a wire to prevent it from falling into the crankcase.

Sprocket Teeth

Automatic Compression Release Removal/

Inspection

NOTE: The automatic compression release mechanism can be inspected and serviced without removing the camshaft from the cylinder head. The actuator ball (C) in the camshaft is not replaceable. Replace the camshaft as an assembly if the actuator ball is worn or damaged.

C

3

A

Inspect for Areas of Tooth

Wear or Damage

9.

Inspect cam sprocket teeth for wear or damage. Replace if necessary.

Decompressor Shaft

Decompressor Ball

Retainer Sleeve

B

1.

Check release lever shaft (A) for smooth operation throughout the entire range of rotation. The spring (B) should hold the shaft weight against the stop pin. In this position, the actuator ball (C) will be held outward in the compression release mode.

2.

Remove release lever shaft and return spring.

3.

Inspect shaft for wear or galling.

4.

Inspect lobe on end of release lever shaft and actuator ball for wear and replace if necessary.

10. Slide camshaft out the PTO side of the cylinder head.

3.17

ENGINE

Automatic Compression Release Installation

1.

Slide spring onto shaft.

2.

Apply engine oil to release lever shaft.

The actuator ball must be held outward to allow installation of the release lever shaft.

Stop Pin

Camshaft Inspection

1.

Visually inspect each cam lobe for wear, chafing or damage.

2.

Thoroughly clean the cam shaft, making sure the oil feed holes are not obstructed.

Spring in relaxed position

Lubrication holes

Lobe Height

If Camshaft Is Removed From Engine:

3.

Turn the camshaft until the actuator ball is in the lowest position and install the release lever shaft.

If Camshaft Is Installed In The Engine:

4.

Use a small magnet to draw the actuator ball outward, or rotate the engine until the cam lobes face upward and install release lever shaft.

5.

Position camshaft as shown at bottom of illustration at right.

6.

Place arm of spring under stop pin as shown and push release lever inward until fully seated. Do not pre-wind the spring one full turn or the compression release will not disengage when the engine starts. Check operation of mechanism as outlined in Step 1 of Removal (above).

NOTE: When shaft is properly installed, actuator ball will be held in the “out” position. It is important to note that spring pressure is very light.

Cam Lobe Height (Intake & Exhaust)

Std: 1.2884-102924” (32.726-32.826 mm)

Limit: 1.2766” (32.426 mm)

3.18

ENGINE

3.

Measure height of each cam lobe using a micrometer.

Compare to specifications.

Journal O.D

Cylinder Head Removal

1.

Remove the two 6mm flange bolts (A) from cylinder head.

See next exploded view on next page.

2.

Loosen each of the four cylinder head bolts (B) evenly 1/8 turn each time in a criss-cross pattern until loose.

B

Journal

Camshaft Journal O.D.:

Mag & PTO End: 1.4935-1.4941”

(37.935- 37.950 mm)

4.

Measure camshaft journal outside diameter (O.D.)

5.

Measure ID of camshaft journal bore.

Camshaft Journal I.D.:

Mag & PTO End: 1.4963-1.4970”

(38.005- 38.025 mm)

Calculate oil clearance by subtracting journal OD from journal bore ID. Compare to specifications.

Camshaft Oil Clearance:

Std: .0022-.0035” (.055-.090 mm)

Limit: .0039” (.10 mm)

NOTE: Replace camshaft if damaged or if any part is worn past the service limit.

NOTE: Replace cylinder head if camshaft journal bore is damaged or worn excessively.

3.

Remove bolts (B) and tap cylinder head lightly with a plastic hammer until loose. CAUTION: Tap only in reinforced areas or on thick parts of cylinder head casting to avoid damaging the thread.

4.

Remove cylinder head and head gasket.

3

3.19

ENGINE

Cylinder Head Exploded View, EH50PL

EH50PL

A

3.20

Cylinder Head Inspection

(A)

1.

Thoroughly clean cylinder head (A) surface to remove all traces of gasket material and carbon.

CAUTION

Use care not to damage sealing surface.

Cylinder Head Warp

ENGINE

Cylinder Head Disassembly

WARNING

Wear eye protection or a face shield during cylinder head disassembly and reassembly.

NOTE: Keep all parts in order with respect to their location in the cylinder head.

3

A

1.

Using a valve spring compressor (A), compress the valve springs and remove the split keeper. NOTE: To prevent loss of tension, do not compress the valve spring more than necessary.

A

Cylinder Head Warp Limit:

.002” (.05 mm)

1.

Lay a straight edge across the surface of the cylinder head at several different points and measure warpage by inserting a feeler gauge between the straight edge and the cylinder head surface. If warpage exceeds the service limit, replace the cylinder head.

2.

Remove spring retainer and spring.

NOTE: The valve springs should be positioned with the tightly wound coils against the cylinder head on progressively wound springs (A).

3.

Push valve out, keeping it in order for reassembly in the same guide.

3.21

ENGINE

4.

Measure free length of spring with a Vernier caliper. Check spring for squareness. Compare to specifications. Replace spring if either measurement is out of specification seat area (B). NOTE: The valves cannot be re-faced or end ground. Valves must be replaced if worn, bent, or damaged.

Measure valve stem in several places

Valve Stem Diameter:

Intake: .2343-.2348” (5.950-5.965 mm)

Exhaust: .2341-.2346” (5.945-5.960 mm)

5.

Remove valve seals. CAUTION: Replace seals whenever the cylinder head is disassembled. Hardened, cracked or worn valve seals will cause excessive oil consumption and carbon buildup.

Valve Inspection

1.

Remove all carbon from valve with a soft wire wheel.

5.

Measure diameter of valve stem with a micrometer in three places and in two different directions (six measurements total). Compare to specifications.

Valve Guide I.D.:

.2362-.2367” (6.0-6.012 mm)

2.

Check valve face for runout, pitting, and burnt spots. To check for bent valve stems, mount valve in a drill or use “V” blocks and use a dial indicator.

A

6.

Measure valve guide inside diameter at the top middle and end of the guide using a small hole gauge and a micrometer.

Measure in two directions, front to back and side to side.

7.

Subtract valve stem measurement to obtain stem to guide clearance.

NOTE: Be sure to measure each guide and valve combination individually

8.

Replace valve and/or guide if clearance is excessive.Compare to specifications.

NOTE: If valve guides are replaced, valve seats must be reconditioned. Refer to Valve Seat Reconditioning for procedure.

B

3.

Check end of valve stem for flaring, pitting, wear or damage

(A).

4.

Inspect split keeper groove for wear or flaring of the keeper

3.22

Combustion Chamber

ENGINE

3.

Heat cylinder head in an oven or use a hot plate to bring cylinder head temperature to 212 o

F (100 o

C).

CAUTION

Do not use a torch to heat cylinder head or warpage may result from uneven heating. Head temperature can be checked with a pyrometer or a welding temperature stick. Wear the appropriate safety equipment for working with heated metal.

Follow the manufacturers instructions provided in the

Valve Seat Reconditioning Kit. Abrasive stone seat reconditioning equipment can also be used. Keep all valves in order with their respective seat.

3

Clean all accumulated carbon deposits from combustion chamber and valve seat area with a soft wire brush.

Valve Seat Reconditioning

Valve Seat Inspection

Inspect valve seat in cylinder head for pitting, burnt spots, roughness, and an uneven surface. If any of the above conditions exist, the valve seat must be reconditioned. If

the valve seat is cracked the cylinder head must be replaced.

Cylinder Head Reconditioning

NOTE: Servicing the valve guides and valve seats requires special tools and a thorough knowledge of reconditioning techniques. Follow the instructions provided in the cylinder head service tool kit. Only use

service kits designed specifically for ATV engines.

CAUTION

Wear eye protection when performing cylinder head service. Valve guide replacement will require heating of the cylinder head. Wear gloves to prevent burns.

Valve Guide Removal/Installation

1.

Remove all carbon deposits from the combustion chamber, valve seat and valve guide area before attempting to remove valve guides.

CAUTION

Carbon deposits are extremely abrasive and may damage the valve guide bore when guides are removed.

2.

Place new valve guides in a freezer for at least 15 minutes while heating cylinder head.

Too Uneven Good Too

Wide

Narrow

NOTE: Valve seat width and point of contact on the valve face is very important for proper sealing. The valve must contact the valve seat over the entire circumference of the seat, and the seat must be the proper width all the way around. If the seat is uneven, compression leakage will result. If the seat is too wide, seat pressure is reduced, causing carbon accumulation and possible compression loss. If the seat is too narrow, heat transfer from valve to seat is reduced and the valve may overheat and warp, resulting in burnt valves.

4.

When thoroughly heated, place cylinder head on blocks of wood which will allow the old guides to be removed.

5.

Using valve guide driver, drive guides out of the cylinder head from the combustion chamber side. Be careful not to damage guide bore or valve seat when removing guides.

3.23

ENGINE

6.

Place cylinder head on cylinder head table. NOTE: Be sure cylinder head is still at 212 o

F (100 o

C) before installing new guides.

11. Apply cutting oil to valve seat and cutter.

Valve Guide Installed Height

Valve Guide Height:

.689-.709” (17.5-18.0 mm)

7.

Place a new guide in the valve guide installation tool and press guide in to proper depth. Check height of each guide above the cylinder head (A). NOTE: The guide can also be driven in to the proper depth. Inspect the guide closely for cracks or damage if a driver is used.

Reaming The Valve Guide

12. Place 46 o

cutter on the pilot and make a light cut.

13. Inspect the cut area of the seat.

• If the contact area is less than 75% of the circumference of the seat, rotate the pilot 180 o

and make another light cut.

• If the cutter now contacts the uncut portion of the seat, check the pilot. Look for burrs, nicks, or runout. If the pilot is bent it must be replaced.

• If the contact area of the cutter is in the same place, the valve guide is distorted from improper installation and must be replaced. Be sure the cylinder head is at the proper temperature and replace the guide.

• If the contact area of the initial cut is greater than

75%, continue to cut the seat until all pits are removed and a new seat surface is evident.

NOTE: Remove only the amount of material necessary to repair the seat surface.

(A)

8.

Allow cylinder head to cool to room temperature. Apply cutting oil to the reamer. Guides should be reamed from the valve spring side of the cylinder head. Ream each guide to size by turning the reamer clockwise continually. Continue to rotate reamer clockwise during removal of the tool.

9.

Clean guides thoroughly with hot soapy water and a nylon brush. Rinse and dry with compressed air. Apply clean engine oil to guides.

10. Install pilot into valve guide.

14. To check the contact area of the seat on the valve face, apply a thin coating of Prussian Blue™ paste to the valve seat. If using an interference angle (46 o

) apply black permanent marker to the entire valve face (A).

15. Insert valve into guide and tap valve lightly into place a few times.

3.24

ENGINE

16. Remove valve and check where the Prussian Blue™ indicates seat contact on the valve face. The valve seat should contact the middle of the valve face or slightly above, and must be the proper width.

• If the indicated seat contact is at the top edge of the valve face and contacts the margin area(B) it is too high on the valve face. Use the 30 o lower the valve seat.

cutter to

• If too low use the 60 o

or 75 face, measure seat width.

o

cutter to raise the seat. When contact area is centered on the valve

• If the seat is too wide or uneven, use both top and bottom cutters to narrow the seat.

• If the seat is too narrow, widen using the 45 seat width after each cut.

o

cutter and re-check contact point on the valve face and

Valve Seat Width:

Intake Std: .028” (.7 mm)

Limit: .055” (1.4 mm)

Exhaust Std: .039” (1.0 mm)

Limit: .071” (1.8 mm)

NOTE: When using an interference angle, the seat contact point on the valve will be very narrow, and is a normal condition. Look for an even and continuous contact point on the black marker, all the way around the valve face.

17. Clean all filings from the area with hot soapy water, rinse, and dry with compressed air.

18. Lubricate the valve guides with clean engine oil, and apply oil or water based lapping compound to the face of the valve. Lapping is not required with an interference angle.

19. Insert the valve into its respective guide and lap using a lapping tool or a section of fuel line connected to the valve stem.

20. Rotate the valve rapidly back and forth until the cut sounds smooth. Lift the valve slightly off of the seat, rotate 1/4 turn, and repeat the lapping process. Do this four to five times until the valve is fully seated, and repeat process for the other valve(s).

A

3

Seat

Width

Bottom - 60 o

or 75 o

Seat - 45 o

or 46 o

Top - 30 o

21. Clean cylinder head, valves, and camshaft oil supply passage (A) thoroughly.

22. If oil passage blind plug was removed, apply Crankcase

Sealant (PN 2871557) or equivalent sealer to the threads and install, torquing to 8 ft. lbs. (11 Nm).

CAUTION

Do not allow sealant to enter oil passage.

23. Spray electrical contact cleaner into oil passage and dry using compressed air.

3.25

ENGINE

Cylinder Head Assembly

CAUTION

Wear eye protection during assembly.

NOTE: Assemble the valves one at a time to maintain proper order.

Valve Sealing Test

1.

Clean and dry the combustion chamber area.

2.

Pour a small amount of clean, high flash point solvent into the intake port and check for leakage around each intake valve. The valve seats should hold fluid with no seepage.

3.

Repeat for exhaust valves by pouring fluid into exhaust port.

Valve Clearance Adjustment

1.

Install new valve seals on valve guides.

2.

Apply engine oil to valve guides and seats.

3.

Coat valve stem with molybdenum disulfide grease.

4.

Install valve carefully with a rotating motion to avoid damaging valve seal.

5.

Dip valve spring and retainer in clean engine oil and install spring with closely spaced coils toward the cylinder head.

Feeler gauge for both valves

NOTE: The valves share a common rocker arm, and must be adjusted using two feeler gauges.

1.

Insert .006 feeler gauge(s) between end of exhaust valve stem and adjuster screw(s).

2.

Loosen locknut(s) and turn adjuster screw(s) until there is a slight drag on feeler gauge(s). The Valve/Clutch Adjuster

Tool (PA-44689) can be used to adjust the 500 engines valves.

NOTE: Both feeler gauges should remain inserted during adjustment of each valve

VALVE CLEARANCE

.006” (.15 mm)

6.

Place retainer on springs and install valve spring compressor. Compress spring only enough to allow split keeper installation and prevent loss of spring tension.

Install split keepers with the gap even on both sides.

7.

Repeat procedure for remaining valve.

8.

When all valves are installed, tap lightly with soft faced hammer on the end of the valves to seat the split keepers.

3.

When clearance is correct, hold adjuster screw and tighten locknut securely

4.

Re-check the valve clearance.

5.

Repeat adjustment procedure if necessary until clearance is correct with locknut secured.

3.26

Cylinder/Piston Removal and Inspection

NOTE: Follow engine disassembly procedures to remove valve cover, camshaft and rocker arms, and cylinder head.

4.

Remove the two 6 mm cylinder base bolts.

ENGINE

1.

Remove cam chain guide at front of cylinder.

5.

Loosen each of the four large cylinder base bolts 1/4 turn at a time in a criss-cross pattern until loose and remove bolts.

NOTE: The bolts are inside the water jacket.

3

2.

Loosen all four oil pipe banjo bolts and then remove the bolts and eight sealing washers. Remove the pipes.

6.

Tap cylinder lightly with a plastic hammer in the reinforced areas only until loose.

7.

Rock cylinder forward and backward and lift it from the crankcase, supporting piston and connecting rod. Support piston with Piston Support Block (PN 2870390).

8.

Remove dowel pins from crankcase.

3.

Loosen hose clamps and remove coolant inlet hose.

3.27

ENGINE

Piston Removal

*By hand: Placing both thumbs as shown, spread the ring open and push up on the opposite side. Do not scratch the ring lands.

A

1.

Remove circlip. Note piston directional arrow pointing toward the right (Mag) side of engine.

1.

Remove piston circlip and push piston pin out of piston. If necessary, heat the crown of the piston slightly with a propane torch.

2.

Remove top compression ring.

3.

Repeat procedure for second ring.

The oil control ring is a three piece design consisting of a top and bottom steel rail and a center expander section. The top rail has a locating tab on the end which fits into a notch (A) in the upper oil ring land of the piston.

4.

Remove the top rail first followed by the bottom rail.

5.

Remove the expander.

Cylinder Inspection

1.

Remove all gasket material from the cylinder sealing surfaces.

CAUTION

Do not apply heat to the piston rings. The ring may lose radial tension

*Using a piston ring pliers: Carefully expand ring and lift it off the piston.

CAUTION

Do not expand the ring more than necessary to remove it from the piston or the ring may break

2.

Inspect the top of the cylinder for warpage using a straight edge and feeler gauge.

Cylinder Warp Limit:

.002” (.05 mm)

3.28

3.

Inspect cylinder for wear, scratches, or damage.

1/2” Down From Top of Cylinder

X

Y

X

Y

ENGINE

2.

Subtract this measurement from the maximum cylinder measurement obtained in Step 5 above.

Piston to Cylinder Clearance

Std: .0006- .0018” (.015- .045 mm)

Piston O.D.:

Std: 3.6204- 3.6215” (91.970-91.985 mm)

Piston/Rod Inspection

3

X

Y

1/2” Up From Bottom

4.

Inspect cylinder for taper and out of round with a telescoping gauge or a dial bore gauge. Measure in two different directions, front to back and side to side, on three different levels (1/2” down from top, in the middle, and 1/

2” up from bottom).

5.

Record measurements. If cylinder is tapered or out of round beyond .002, the cylinder must be re-bored oversize or replaced.

Cylinder Taper

Limit: .002 Max.

Cylinder Out of Round

Limit: .002 Max.

Piston Pin Bore

Piston Pin Bore:

.9055-.9057” (23.0-23.006 mm)

1.

Measure piston pin bore.

Standard Bore Size:

3.6221-3.6228” (92.00 - 92.012 mm)

Piston-to-Cylinder Clearance

Piston

Piston Pin Measurement Locations

Piston Pin O.D.

.9053-.9055” (22.994-23.0 mm)

40 mm

Piston Pin

1.

Measure piston outside diameter at a point 40 mm down from the top of the piston at a right angle to the direction of the piston pin.

3.29

ENGINE

Piston Ring Installed Gap

1.

Place each piston ring inside cylinder using piston to push ring squarely into place as shown at right.

Feeler Gauge

Cylinder

25-50 mm

2.

Measure piston pin O.D. Replace piston and/or piston pin if out of tolerance.

3.

Measure connecting rod small end ID.

Piston

Ring

Feeler Gauge

Piston Ring

Piston Ring Installed Gap

Top Ring

Std: .0079- .0138” (.20- .36 mm)

Limit: .039” (1.0 mm)

Second Ring

Std: .0079- .0138” (.20- .36 mm)

Limit: .039” (1.0 mm)

Oil Ring

Std: .0079- .0276” (.20- .70 mm)

Limit: .059” (1.5 mm)

Piston Ring-to-Groove Clearance

Top Ring Std: .0016-.0031” (.040-.080 mm)

Limit: .0059” (15 mm)

Second Ring Std: .0012-.0028” (.030-.070 mm)

Limit: .0059” (15 mm)

4.

Measure piston ring to groove clearance by placing the ring in the ring land and measuring with a thickness gauge.

Replace piston and rings if ring-to-groove clearance exceeds service limits

2.

Measure installed gap with a feeler gauge at both the top and bottom of the cylinder.

NOTE: A difference in end gap indicates cylinder taper.

The cylinder should be measured for excessive taper and out of round

3.

If the bottom installed gap measurement exceeds the service limit, replace the rings. If ring gap is below specified limit, file ring ends until gap is within specified range.

NOTE: Always check piston ring installed gap after reboring a cylinder or when installing new rings. A re-bored cylinder should always be scrubbed thoroughly with hot soapy water, rinsed, and dried completely. Wipe cylinder bore with an oil rag immediately to remove residue and prevent rust.

Crankcase Disassembly

NOTE: The recoil starter, starter motor, starter drive, flywheel, stator, cam chain and sprockets can be serviced with the engine in the frame.

3.30

Starter Drive Removal/Inspection

1.

Remove recoil housing bolts and remove housing.

2.

Remove starter drive assembly. Note the thrust washer located at the rear of the drive mechanism.

3.

Inspect the thrust washer for wear or damage and replace if necessary.

ENGINE

5.

Measure the ID of the bushing in the recoil housing (A) and in the crankcase and record. Measure in two directions 90 o apart to determine if bushing is out of round. Calculate bushing clearance. Replace bushing if clearance exceeds the service limit.

6.

Inspect gear teeth on starter drive. Replace starter drive if gear teeth are cracked, worn, or broken.

Flywheel/Stator Removal/Inspection

1.

Remove flywheel nut and washer.

2.

Install Flywheel Puller (PN 2871043) and remove flywheel.

CAUTION

3

Do not thread the puller bolts into the flywheel more than 1/4" or stator coils may be damaged

3.

Mark or note position of stator plate on crankcase.

4.

Remove bolts and carefully remove stator assembly, being careful not to damage crankshaft bushing on stator plate.

5.

Replace crankshaft seal (A).

A

A

Std. Bushing ID:

.4735”-.4740” (11.11-12.04 mm)

Std. Shaft OD:

.470”-.472” (11.93-11.99 mm)

Starter Drive Bushing Clearance:

Std: .0015-.004” (.038-.102 mm)

Service Limit:

.008” (.203 mm)

4.

Measure the OD of the starter drive shaft on both ends and record.

6.

Remove oil passage O-Ring (B).

B

3.31

ENGINE

7.

Remove large sealing O-Ring from outer edge of stator plate.

section of chain. Replace if worn past service limit.

Chain Service Limit: 5.407” (13.7 cm)

4.

Using the special socket, remove the crankshaft slotted nut.

NOTE: The crankshaft slotted nut is a left-hand thread.

5.

Remove cam chain drive sprocket and woodruff key from crankshaft.

6.

Inspect sprocket teeth for wear or damage.

7.

Inspect woodruff key for wear.

8.

Replace any worn or damaged parts.

One Way Valve Removal

The one way valve prevents oil from draining out of the oil tank and into the crankcase when the engine is off. It must be clean and have adequate spring pressure in order to seal properly.

Cam Chain/Tensioner Blade

1.

Remove bolt securing tensioner blade to crankcase (A).

A

D

C

B

A

2.

Remove blade and inspect for cracks, wear, or damage.

B

1.

Remove cap bolt (A), sealing washer (B), spring (C), and one way valve (D) from PTO side crankcase.

2.

Inspect free length of spring and check coils for distortion.

One Way Valve Spring Free Length:

Std: 1.450” (3.68 cm)

3.

Inspect valve for wear.

4.

Check seat area for nicks or foreign material that may prevent proper sealing of valve.

20 Pitch Section

3.

Remove cam chain (B). Inspect chain for worn or missing rollers or damage. Stretch chain tight on a flat surface and apply a 10 lb. (4.53 kg) load. Measure length of a 20 pitch

3.32

Crankcase Separation

ENGINE

3.

Inspect drive gear teeth for cracks, damage or excessive wear.

1.

Remove flange bolts (10) from magneto side crankcase evenly in a criss-cross pattern.

2.

Separate crankcase by tapping with a soft faced hammer in reinforced areas.

3.

Tap lightly on balancer gear with a brass drift through the hole in the crankcase if necessary, to ensure the balancer shaft stays in the PTO side crankcase. Watch the gap along the crankcase mating surface and separate the crankcase evenly. It may also be necessary to tap the oil pump shaft lightly to separate the crankcase.

CAUTION

Do not strike the oil pump shaft at an angle or the shaft may bend, causing irreparable damage. Tap only lightly on the pump shaft if necessary.

4.

Remove the Mag (RH) crankcase from the PTO case.

Oil Pump Removal/Inspection

4.

Remove three oil pump retaining bolts and pump.

5.

Inspect mating surface of crankcase and oil pump. Check for nicks, burrs, or surface irregularities.

6.

Remove the three screws and strainer screen from pump.

7.

Clean screen thoroughly.

8.

Remove pump body screw and feed chamber cover.

3

C

A

B

1.

Remove pump shaft bearing (A) and thrust washer (B) from pump shaft.

2.

Remove (2) bolts holding pump drive gear (C).

3.33

ENGINE

9.

Measure pump end clearance using a feeler gauge and straight edge.

Oil Pump Assembly

1.

Clean and dry all parts thoroughly. Apply clean engine oil to all parts. Do not use gasket sealer on the pump body mating surfaces or oil passages will become plugged.

2.

Install pump shaft and scavenge rotor drive pin.

3.

Install outer scavenge rotor, inner scavenge rotor, and scavenge casing.

4.

Install outer feed rotor and inner feed rotor drive pin.

5.

Install inner feed rotor and feed chamber cover with screw.

6.

Tighten screw securely.

7.

Install screen on pump body.

8.

Install oil pump on crankcase and torque bolts to 6 ft. lbs.

(8 Nm).

Oil Pump Attaching Bolt Torque:

6 ft. lbs. (8 Nm)

Pump End Clearance:

Std: .001 -.003 (.0254-.0762 mm)

Wear Limit: .004 (.1016 mm)

10. Measure clearance between outer feed rotor and pump body with a feeler gauge.

Counter Balancer Shaft Removal/Inspection

1.

Remove the shim washer (A) from the counter balancer shaft.

A

Rotor Tip Clearance:

Std: .005 (.127 mm)

Wear Limit: .008 (.2032 mm)

11. Measure rotor tip clearance with a feeler gauge.

12. Remove inner and outer feed rotor and pump chamber body.

13. Repeat measurements for scavenge rotor.

14. Remove inner and outer scavenge rotor and inspect pump shaft for wear.

2.

Note the alignment dots on the balancer and crankshaft gears, the marks must be aligned during reassembly.

3.34

ENGINE

3.

Turn the shaft until balancer counter weights clear the crankshaft and remove the balancer shaft from the crankcase.

8.

Support the PTO side crankcase and crankshaft; press the crankshaft out. Be careful not to damage the crankcase mating surface or connecting rod.

4.

Inspect the balancer drive gear and pump shaft drive gear.

5.

Replace the shaft if gear teeth are abnormally worn or damaged.

6.

Inspect the balancer shaft bearings.

NOTE: Due to extremely close tolerances and minimal wear, the balancer shaft ball bearings must be inspected visually and by feel. Look for signs of discoloration, scoring or galling. Turn the inner race of each bearing.

The bearings should turn smoothly and quietly. The outer race of each bearing should fit tightly in the crankcase.

The inner race should be firm with minimal side to side movement and no detectable up and down movement.

Crankshaft Removal/Inspection

A

9.

Use a feeler gauge to measure the connecting rod big end side clearance.

Connecting Rod Big End Side Clearance:

Std: .0039-.0256” (.1-.65 mm)

Limit: .0315” (.80 mm)

10. Place the crankshaft in a truing stand or V-blocks and measure the runout on both ends with a dial indicator.

Max Runout: .0024” (.06 mm)

11. Measure the connecting rod big end radial clearance.

Big End Radial Clearance:

Std: .0004-.0015” (.011-.038 mm)

Limit: .0020” (.05 mm)

12. Inspect the crankshaft main bearing journals for scoring and abnormal wear.

3

7.

Remove the shim washer (A) from the crankshaft.

3.35

ENGINE

Crankcase Bearing Inspection Pump Shaft Oil Seal/Water Pump Mechanical

Seal Removal (Engine Disassembled)

NOTE: The water pump mechanical seal can be removed without removing the engine. Refer to Water

Pump Mechanical Seal Installation.

Replace the pump shaft seal and water pump mechanical seal whenever the crankcase is disassembled.

1.

Remove the seal from the PTO side crankcase.

2.

Inspect the crankshaft main bearings, balancer shaft bearings, and pump shaft bearing.

NOTE: Due to extremely close tolerances and minimal wear, the bearings must be inspected visually, and by feel. Look for signs of discoloration, scoring or galling.

Turn the inner race of each bearing. The bearings should turn smoothly and quietly. The outer race of each bearing should fit tightly in the crankcase. The inner race should be firm with minimal side to side movement and no detectable up and down movement.

3.

Support the crankcase and drive or press the main bearings out of each crankcase.

4.

To remove balancer shaft bearings and pump shaft bearing use a blind hole bearing puller.

NOTE: Bearings are stressed during the removal process and should not be re-used!

1.

Remove the pump shaft bearing from the Magneto (right hand) side crankcase.

2.

Pry out the oil seal, noting the direction of installation with the spring side facing IN (toward inside of case).

3.

Drive the water pump mechanical seal out of the crankcase from inside to outside. Note: The new mechanical seal must be installed after the crankcases are assembled, using a special tool. See Mechanical Seal Installation.

Crankcase Inspection

1.

Remove all traces of gasket sealer from the crankcase mating surfaces. Inspect the surfaces closely for nicks, burrs or damage.

2.

Check the oil pump and oil passage mating surfaces to be sure they are clean and not damaged.

3.36

ENGINE

Bearing Installation

NOTE: To ease bearing installation, warm the crankcase until hot to the touch. Place the bearings in a freezer.

1.

Install the bearings so the numbers are visible.

2.

Drive or press new bearings into the crankcases, using the proper driver.

CAUTION

Press only on outer race of bearing to prevent bearing damage

• 70 mm (2.755") driver- For crankshaft main bearings.

• 46 mm (1.810") For counter balancer bearings.

• 28 mm (1.100") For pump shaft bearing.

End Play Inspection/Adjustment

Before reassembling the crankcase,the following steps should be performed to determine the amount of crankshaft, counter balancer shaft, and pump shaft end play. Excessive end play may cause engine noise at idle and slow speeds. Too little play will side load the bearings which may lead to premature bearing failure.

Crankshaft End Play Adjustment

3.

Make sure all bearings are firmly seated in the both Mag and PTO crankcase.

4.

Measure the distance from the PTO crankcase mating surface to the main bearing using a dial caliper and a straight edge.

5.

Subtract the thickness of the straightedge from the measurement obtained in Step 2 and record.

3

PTO Case Depth_________________________

3.37

ENGINE

6.

Measure the distance from the Magneto crankcase mating surface to the main bearing using the same method and record.

10. Subtract the Crankshaft Width measured in Step 7 from the

Total Case Width recorded in Step 6, and record below.

Total End Play_____________

11. Subtract the thickness of the existing shim from the result of Step 8 to determine if a different shim is required. The result must be within the specified range listed.

Crankshaft End Play: .008-.016” (.02-.04 cm)

Counter Balancer Shaft End Play

Adjustment.

7.

Subtract the thickness of the straightedge from the measurement obtained in Step 4 and record.

Mag Case Depth_______________

8.

Add the readings recorded in Step 3 and Step 5 and record below.

Total Case Width_________________

12. Make sure all bearings are firmly seated in the crankcase.

13. Measure the width of the counter balancer shaft at the bearing seats with a dial caliper or micrometer, and record reading.

9.

Measure the width of the crankshaft at the bearing seats with a micrometer or dial caliper and record.

Crankshaft Width____________

3.38

ENGINE

14. Measure the distance from the Mag crankcase mating surface to the balance shaft bearing using a dial caliper and a straight edge. Subtract the thickness of the straightedge and record.

15. Measure the distance from the PTO crankcase mating surface to the bearing using the same method outlined in

Step 1, 2, and-3.

16. Add the readings obtained in Step 3 and Step 4.

17. Subtract the counter balancer shaft width measured in Step

2 from the figure obtained in Step 5.

18. Subtract the thickness of the existing shim from the result of Step 6 to determine if a different shim is needed. The result must be within the specified range listed at below.

Counter Balance Shaft End Play:

.008”-.016” (.02-.04 cm)

3.

Install the gear on the oil pump and measure the width of the pump and gear. Subtract this measurement from the measurement recorded in Step 2.

4.

Subtract the thickness of the existing shim from the result of Step 3 to determine if a different shim is needed. See

Shaft End Play Spec.

Oil Pump Shaft End Play:

.008”-.016” (.02-.04 cm)

3

Oil Pump Shaft End Play Adjustment

1.

Make sure the pump shaft bearing is firmly seated in the

Magneto side crankcase.

2.

Measure the distance from the magneto crankcase mating surface to the bearing using a dial caliper and a straight edge. Subtract the thickness of the straightedge and record.

3.39

ENGINE

ENGINE REASSEMBLY

Pump Shaft Oil Seal Installation

1.

Install the seal from the outside of the crankcase (water pump side) with the spring facing inward, toward the pump shaft bearing.

2.

Drive or press the seal into place using a 25 mm (.985") seal driver, until flush with the outer edge of the seal bore.

3.

Lubricate the seal lip with grease.

Crankshaft/Counter Balance/Oil Pump

Installation

Lubricate all bearings with clean engine oil before assembly.

Use the Crankshaft/Water Pump Installation Kit (PN

2871283) to prevent damage to the crankshaft and main bearings during installation.

1.

Install the crankshaft into the PTO side crankcase. Screw the threaded rod into the crankshaft until the threads are engaged a minimum of one inch (25.4mm).

2.

Install the collar, washer, and nut onto the threaded rod.

Hold the crankshaft and tighten the nut to draw the crankshaft into the main bearings until fully seated. Loosen the nut and remove the threaded rod from the crankshaft.

If removal is difficult, install two nuts on the end of the threaded rod and tighten against each other.

3.

Install the proper shim on the magneto end of the crankshaft.

4.

Place the balancer shaft in the PTO crankcase aligning the timing marks on the crankshaft and balancer gears. Install the proper shim washer on the shaft.

5.

Inspect the oil pump sealing surface on the crankcase.

Apply a light film of engine oil to the surface and install the oil pump.

NOTE: Do not use gasket sealer on the pump mating surfaces.

NOTE: After engine is assembled and machine is readied for field operation, oil pump MUST be primed.

Follow oil pump priming procedure.

Oil Pump Bolt Torque:

6 ft. lbs. (8 Nm)

6.

Align the drive gear with the drive pin on the pump shaft and install the gear. Be sure the gear is fully seated and properly engaged.

7.

Install the proper shim washer on the pump shaft.

3.40

ENGINE

Crankcase Assembly

1.

Apply Crankcase Sealant (PN 2871557) to the crankcase mating surfaces. Be sure the alignment pins are in place.

2.

Set the crankcase in position carefully to avoid damaging the pump shaft seal, and install the magneto end crankshaft installation tool (follow instructions provided with the

Crankshaft/Water Pump Installation Kit (PN 2871283).

Draw the crankcase halves together by tightening the nut on the tool and tapping lightly in the pump shaft area with a soft faced hammer to maintain alignment. Continually check alignment of the cases during installation, closing the gap equally until the surfaces are tightly seated.

3.

Remove the tool.

4.

Install the crankcase flange bolts and tighten in 3 steps following the pattern to specified torque.

Crankcase Bolt Torque:

14 ft. lbs. (19 Nm)

Crankcase Sealant:

(PN 2871557)

Water Pump Mechanical Seal Removal -

Engine Installed

Water Pump Mechanical Seal

Puller: (PN 2872105)

Replacement T-Handle:

(PN 2872106)

This tool allows a technician to replace the mechanical water pump seal on EH50PL engines without removing the engine and splitting the cases.

CAUTION

Improper or careless use of this tool or procedure can result in a bent water pump shaft.Pump shaft replacement requires engine removal and crankcase separation. Use caution while performing this procedure. Make sure that the puller is parallel to the shaft at all times. Do not place side loads on the water pump shaft or strike the puller or shaft in any way.

1.

After the coolant has been drained, remove the water pump cover, impeller and the sealing washer. (Ill. 1).

Sealing Washer

3

Water Pump Mechanical Seal Installation

5.

Clean the seal cavity to remove all traces of old sealer.

6.

Place a new mechanical seal in the seal drive collar, and install on the pump shaft.

7.

Screw the guide onto the end of the pump shaft.

8.

Install the washer and nut and tighten to draw seal into place until fully seated.

9.

Remove the guide adaptor using the additional nut as a jam nut if necessary.

Sealing Washer

(Copper or Aluminium)

Coolant Drain

Bolt

Oil

Seal

Impeller

Mechanical Seal

III. 1

3.41

ENGINE

2.

Slide the main puller body over the outer portion of the mechanical seal as shown in Ill. 2 and turn T-Handle clockwise until it contacts water pump shaft. Continue rotating until outer portion of mechanical seal is separated from the metal seal body.

5.

Tighten the hex socket screws on the puller legs sufficiently so the lip of the puller legs will grasp the mechanical seal.

Ill. 5.

T-Handle

T-Handle

Main Puller Body

III. 2

3.

Insert the puller legs between the water pump drive shaft and the remaining portion of the mechanical seal. Attach the puller legs to the main puller body. Ill. 3

Main puller body

Position the split

90 o

to opening on main puller body

III.3

4.

Ensure that the split between the puller legs are fully supported by the main body of the tool (Ill 4).

Hex Socket Screws

Main Puller Body

III. 5

6.

Turn the puller T-Handle clockwise until it contacts the water pump shaft. Continue rotating until the remaining portion of mechanical seal has been removed from the cases. Ill. 6 Pump shaft oil seal can also be replaced at this time if necessary.

7.

The Water Pump Install Kit (PN 5131135) is required to install the new mechanical seal. This tool is available separately and it is also included in the Crankshaft/Water

Pump Seal Installation Kit (PN 2871283).

One Way Valve Installation

Install the one way valve plunger, spring, and plug using a new sealing washer.

One Way Valve Plug Torque:

16 ft. lbs. (22 Nm)

Puller Legs

III. 4

3.42

Lip must grasp inside of mechanical seal

ENGINE

Cam Chain Drive Sprocket Installation

1.

Install the Woodruff key, drive sprocket, and slotted nut.

Tighten the nut to the specified torque.

B

NOTE: The top rail has a locating tab to prevent rotation. The tab must be positioned in the notch on the side of the piston as shown (A).

A

3

Tighten

Slotted Nut Torque:

35-51 ft. lbs. (47-69 Nm)

Tensioner Blade Installation

1.

Install the tensioner blade and tighten the mounting bolt to specified torque.

Tensioner Blade Mounting Bolt Torque:

6 ft. lbs. (8 Nm)

3.

Install the bottom rail with the gap at least 30 o

from the end of the expander on the side opposite the top rail gap.(See

ILL. 1).

4.

Install the second ring with the “R” mark facing up.

Position the end gap toward the rear (intake) side of the piston.

5.

Install the top ring (chrome faced) with the “R” mark facing up and the end gap facing forward (toward the exhaust).

(See ILL. 1).

6.

Check to make sure the rings rotate freely in the groove when compressed.

Ring Profile

Piston Ring Installation

NOTE: Apply clean engine oil to all ring surfaces and ring lands. Always check piston ring installed gap before rings are installed on piston. If the piston has been in service clean any accumulated carbon from the ring grooves and oil control ring holes.

1.

Place the oil control ring expander in oil ring groove with the end gap facing forward. The expander has no up or down marking and can be installed either way. The ends should butt squarely together and must not overlap.

2.

Install the oil ring top rail.

Mark- up

Top

Second

ILL. 1

Mark- up

3.43

ENGINE

Piston Installation

1.

Clean the gasket surfaces on the cylinder and crankcase.

Remove all traces of old gasket material.

2.

Make sure the cylinder mounting bolt holes are clean and free of debris.

Tang Outward

Cylinder Installation

7.

Place the dowel pins in the crankcase and install a new cylinder base gasket.

8.

Position the Piston Support Block (PN 2870390) (A) beneath the piston skirt to support the piston during cylinder installation.

A

3.

Install a new circlip on one side of the piston with the end gap facing up or down, and tang outward.

CAUTION

Circlips become deformed during the removal process.

Do not re-use old circlips. Do not compress the new clip more than necessary upon installation to prevent loss of radial tension. Severe engine damage may result if circlips are re-used or deformed during installation.

4.

Apply clean engine oil to the piston rings, ring lands, piston pin bore, piston pin, and piston skirt. Lubricate the connecting rod (both ends), balancer drive gear, and crankshaft main bearing area.

9.

Apply clean engine oil to a ring compressor and install the compressor following manufacturers instructions.

CAUTION

Make sure the oil control ring upper rail tab is positioned properly in the notch of the piston. Verify all ring end gaps are correctly located.

or :

Mag

5.

Install the piston on the connecting rod with the arrow or : mark facing the magneto (RH) end of the crankshaft. The piston pin should be a push fit in the piston.

6.

Install the other circlip with the gap facing up or down and tang outward. (See Caution with Step 3 above). Push the piston pin in both directions to make sure the clips are properly seated in the groove.

3.44

10. Apply clean engine oil liberally to the cylinder bore and tapered area of the sleeve. Install the cylinder with a slight rocking motion until the rings are captive in the sleeve.

ENGINE

The following procedure must be used to torque the cylinder head properly:

Torque all bolts evenly in a criss- cross pattern

*Torque bolts to 22 ft. lbs. (30 Nm)

*Torque bolts to 51 ft. lbs. (70 Nm)

*Loosen bolts evenly 180 o

(1/2 turn)

*Loosen bolts again another 180 o

(1/2 turn)

*Torque bolts to 11 ft. lbs. (15 Nm)

*From this point, tighten bolts evenly 90 o

(1/4 turn)

*Finally, tighten another 90 o

(1/4 turn)

*Install two 6 mm bolts and torque to 6 ft. lbs. (8 Nm)

3

11. Remove the ring compressor and support block.

12. Push the cylinder downward until fully seated on the base gasket.

13. Apply a light film of oil to the threads and flange surface of the cylinder mounting bolts.

14. Install all four bolts finger tight. Rotate the engine and position the piston at BDC.

NOTE: If cam chain is installed, hold it up while rotating the engine to avoid damage to the chain, drive sprocket teeth, or tensioner blade.

15. Tighten the cylinder bolts in three steps in a criss cross pattern and torque to specifications.

16. Install the two 6 mm bolts and torque to specifications.

Cylinder Bolt Torque:

10 mm - 46 ft. lbs. (62 Nm)

6 mm - 6 ft. lbs. (8 Nm)

Guide in recess

Cylinder Head Installation

Clean the gasket surfaces on the cylinder head and cylinder. Remove all traces of old gasket material.

Refer to disassembly photos.

1.

Install the cam chain tensioner guide. Be sure bottom end of guide is located properly in crankcase.

2.

Install the two dowel pins and a new cylinder head gasket.

3.

Place the cylinder head on the cylinder. Apply a film of engine oil to the cylinder head bolt threads and washers, and hand tighten the bolts.

Cam Chain/Camshaft Installation

Install the cam chain over the crankshaft.

CAUTION

Serious engine damage may result if the camshaft is not properly timed to the crankshaft.

3.45

ENGINE

IMPORTANT CAMSHAFT TIMING NOTE: In order to time the camshaft to the crankshaft, the piston must be precisely located at Top Dead Center (TDC).

Camshaft Timing

4.

Loop the cam chain on the cam sprocket with the dots on the sprocket facing outward and the alignment pin notch facing directly upward.

A

1.

Apply Polaris Premium Starter Drive Grease (PN

2871460) to the camshaft main journals and cam lobes.

Lubricate automatic compression release mechanism with clean engine oil.

2.

Install the camshaft with the lobes facing downward and the sprocket alignment pin facing upward.

3.

Disconnect the wire from the cam chain and rotate the engine to align the single (TDC ) timing mark (Top Dead

Center) on the flywheel with the notch in the timing inspection window. Be sure to use the single TDC mark when installing the cam. Do not use the advance marks. See illustration.

Single (TDC)

Mark Aligned

5.

Before positioning the sprocket on the camshaft, check the position of the cam sprocket alignment pin. When the cam is positioned properly, the cam sprocket alignment pin (A) is directly in line with the crankshaft/camshaft centerline

(B).

B

A

3.46

6.

Install the sprocket on the camshaft. Apply Loctite™ 242

(PN 2871949) to the cam sprocket bolts and torque to specification.

Cam Sprocket Bolt Torque:

6 ft. lbs. (8 Nm)

Single (TDC)

Mark Aligned

7.

Verify TDC mark in timing inspection hole and alignment pin is directly in line with crankshaft to camshaft centerline.

Refer to illustration.

8.

Apply Crankcase Sealant (PN 2871557) to the camshaft end cap and install using a new O-Ring.

9.

Check all cam timing marks to verify proper cam timing, and install the cam chain tensioner body with a new gasket.

10. After tensioner installation, rotate engine at least two revolutions and re-check marks/timing.

ENGINE

3

3.47

ENGINE

CAMSHAFT TIMING

Dots

Crankshaft to Camshaft Centreline

Sprocket Alignment Pin

3.48

Single TDC Mark Aligned

TDC Mark

Rotation

Do Not Use

Advance Marks

ENGINE

Cam Chain Tensioner Installation

1.

Release the ratchet pawl (A) and push the tensioner plunger (B) all the way into the tensioner body.

3.

Apply 3 Bond 1215 (PN 2871557) or an equivalent sealer to the stator plate outer surface and install a new O-Ring.

B

A

2.

Install the tensioner body with a new gasket and tighten the bolts.

Tensioner Bolt Torque:

6 ft. lbs. (8 Nm)

3.

Install the spring, new sealing washer, and tensioner plug.

Tensioner Plug Torque:

17 ft. lbs. (23 Nm)

4.

Install the stator plate being careful not to damage the seal.

Align timing reference marks on the plate and crankcase.

Be sure the plate is fully seated.

NOTE: This is a static timing mark. Strobe timing should be performed after start up.

5.

Torque bolts evenly to specification.

Stator Plate Bolt Torque:

5-6.5 ft. lbs. (7-9 Nm)

4.

Slowly rotate engine two to three revolutions and re-check cam timing.

Stator, Flywheel and Starter Drive

Installation

NOTE: The stator, flywheel, starter drive, and recoil can be assembled with the engine in the frame.

Stator

1.

Apply a light film of grease to the crankshaft seal. Apply molybdenum disulfide grease or assembly lubricant to the crankshaft bushing.

2.

Install a new O-Ring in the oil passage recess in the crankcase.

6.

Seal stator wire grommet with Crankcase Sealant (PN

2871557) or equivalent sealer.

Flywheel

1.

Install flywheel, washer, and nut. Torque flywheel to specification.

Flywheel Nut Torque:

58-72 ft. lbs. (78-98 Nm)

Starter Drive

3

1.

Be sure the washer is positioned on the back of the drive

3.49

ENGINE

gear.

Apply Starter Drive

Grease to Bushing install the cover and bolts.

Rocker Cover Bolt Torque:

6 ft. lbs. (8 Nm)

Thermostat Installation

2.

Apply starter drive grease to the drive bushing in the crankcase and all moving surfaces of the starter drive mechanism. Install the starter drive.

3.

Install recoil housing gasket and recoil housing.

Starter Drive Grease:

(PN 2871460)

Install the thermostat with one of the air bleed holes positioned next to the upper thermostat cover bolt hole as shown.

Oil Pipes

Install the oil pipes with new sealing washers. Tighten all bolts evenly to specified torque.

Rocker Shaft/Rocker Arm Assembly

Installation

1.

Assemble rocker arms, rocker shaft, and shaft supports.

2.

Install and tighten rocker arm shaft locating bolt.

3.

Apply starter drive grease to the cam lobes and cam follower surfaces.

4.

Rotate the engine until the cam lobes are pointing downward.

5.

Be sure the dowel pins are in place and install the rocker shaft assembly.

6.

Apply a light film of engine oil to the threads of the bolts and tighten evenly.

Rocker Shaft Support Tower Bolt Torque:

9 ft. lbs. (12 Nm)

Oil Pipe Bolt Torque:

20 ft. lbs. (27 Nm)

Rocker Shaft Locating Bolt Torque:

6 ft. lbs. (8 Nm)

7.

Adjust valves according to the valve adjustment procedure found in Chapter 2, Maintenance.

8.

Apply clean engine oil liberally to the valve springs, cam chain, rocker arms, and camshaft.

9.

Place a new rocker cover gasket on the cylinder head and

3.50

RECOIL

Recoil Disassembly/Inspection

CAUTION

The recoil is under spring tension. A face shield and eye protection is required during this procedure.

Replace any parts found to be worn or damaged.

A

ENGINE

5.

Inspect plate for wear or damage. Inspect plate friction spring for wear, damage, and proper tension. The spring should fit tightly on friction plate.

3

1.

Remove bolts and recoil from the engine.

2.

Pull recoil rope (if applicable) so it is extended approximately 12-18" (30-46cm). Check handle c-ring for proper tension, and the handle for cracks or damage which may allow water or dirt to enter the recoil housing through the rope.

3.

Remove handle from the rope and allow spring tension on recoil to relax.

NOTE: The handle must seal tightly on the recoil housing to prevent water from entering.

4.

Remove center bolt from recoil friction plate (A).

6.

Remove ratchet pawl with spring and inspect. Replace spring or ratchet pawl if worn, broken, or damaged.

NOTE: Long arm of spring engages reel. Short end against pawl.

7.

Hold reel firmly in housing. Pull rope handle until 12-18"

(30-46cm) of rope is exposed, and hold reel in place.

8.

Place rope in notch on outer edge of reel. Release tension on hub and allow reel to unwind approximately 6-7 turns until spring tension is released.

A

9.

Slowly and carefully remove reel from recoil housing making sure the spring remains in the housing. Inspect the reel hub and bushing (A) for wear.

10. Unwind rope and inspect for cuts or abrasions.

11. Inspect drive tab on hub return spring for damage. To remove hub return spring, hold outer coils in place with one hand and slowly remove spring one coil at a time from the inside out.

12. Pull knot out of recoil reel. Untie knot. Remove rope from reel.

3.51

ENGINE

Recoil Assembly

CAUTION

Be sure to wear a face shield and eye protection when performing this procedure.

post of the housing and the bushing.

To install a new spring:

1.

Place spring in housing with the end positioned so the spring spirals inward in a counterclockwise direction. See photo at right.

2.

Hold spring in place and cut retaining wire.

To reinstall an old spring:

1.

Hook outer tab in place in recoil housing and wind spring in a counterclockwise direction one coil at a time while holding the installed coils in place.

2.

Lubricate the spring with light lubricant such as Premium

All Season Grease (PN 2871423).

To complete recoil assembly:

1.

Route rope through guide bushing in recoil housing and into reel. Tie a secure knot in end of the rope.

2.

Wind rope counterclockwise onto the reel, as viewed from ratchet side of reel.

3.

Lock rope into notch on outer edge of reel.

4.

Apply a small amount of grease or equivalent to the center

5.

Install reel into housing making sure the spring drive tab on the reel engages the spring and the reel is fully seated in the housing.

6.

Apply downward pressure on the reel and rotate counterclockwise approximately 6-7 turns to pre-wind the spring. Continue rotating counterclockwise until rope on outer edge aligns with rope guide bushing.

7.

Release rope from notch and allow reel to rewind completely. If more pre-wind is required, place rope in notch and add additional turns of pre-wind.

8.

Install ratchet pawl and return spring, with long leg of spring engaged in reel.

9.

Reinstall friction plate.

NOTE: The friction plate must be positioned with both end tabs of the friction spring opposite the ratchet pawl.

10. Torque friction plate retaining bolt to 5-6 ft. lbs. (7-9 Nm).

11. Reinstall recoil housing using a new gasket. Seal stator wire harness grommet with RTV silicone.

3.52

TROUBLESHOOTING

Spark Plug Fouling

• Spark plug cap loose or faulty

• Choke cable adjustment or plunger/cable sticking

• Foreign material on choke plunger seat or plunger

• Incorrect spark plug heat range or gap

• Carburetor inlet needle and seat worn

• Jet needle and/or needle jet worn or improperly adjusted

• Excessive carburetor vibration (loose or missing needle jet locating pins)

• Loose jets in carburetor or calibration incorrect for altitude/temperature

• Incorrect float level setting

• PVT system calibrated incorrectly or components worn or mis-adjusted

• Fuel quality poor (old) or octane too high

• Low compression

• Restricted exhaust

• Weak ignition (loose coil ground, faulty coil, stator, or ETC switch)

• ETC switch mis-adjusted

• Restricted air filter (main or pre-cleaner) or breather system

• Improperly assembled air intake system

• Restricted engine breather system

• Oil contaminated with fuel

• Restricted oil tank vent

Engine

Engine Turns Over But Fails to Start

• No fuel

• Dirt in fuel line or filter

• Fuel will not pass through fuel valve

• Fuel pump inoperative/restricted

• Tank vent plugged

• Carb starter circuit

• Engine flooded

• Low compression (high cylinder leakage)

• No spark (Spark plug fouled)

ENGINE

Engine Does Not Turn Over

• Dead battery

• Starter motor does not turn

• Engine seized, rusted, or mechanical failure

Engine Runs But Will Not Idle

• Restricted carburetor pilot system

• Carburetor misadjusted

• Choke not adjusted properly

• Low compression

• Crankcase breather restricted

Engine Idles But Will Not Rev Up

• Spark plug fouled/weak spark

• Broken throttle cable

• Obstruction in air intake

• Air box removed (reinstall all intake components)

• Incorrect or restricted carburetor jetting

• ETC switch limiting speed

• Reverse speed limiter limiting speed

• Carburetor vacuum slide sticking/diaphragm damaged

• Incorrect ignition timing

• Restricted exhaust system

3

3.53

ENGINE

Engine Has Low Power

• Spark plug fouled

• Cylinder, piston, ring, or valve wear or damage

(check compression)

• PVT not operating properly

• Restricted exhaust muffler

• Carburetor vacuum slide sticking/diaphragm damaged

• Dirty carburetor

Piston Failure - Scoring

• Lack of lubrication

• Dirt entering engine through cracks in air filter or ducts

• Engine oil dirty or contaminated

Excessive Smoke and Carbon Buildup

• Excessive piston-to-cylinder clearance

• Wet sumping

• Worn rings, piston, or cylinder

• Worn valve guides or seals

• Restricted breather

• Air filter dirty or contaminated

Low Compression

• Decompressor stuck

• Cylinder head gasket leak

• No valve clearance or incorrectly adjusted

• Cylinder or piston worn

• Piston rings worn, leaking, broken, or sticking

• Bent valve or stuck valve

• Valve spring broken or weak

• Valve not seating properly (bent or carbon accumulated on sealing surface)

• Rocker arm sticking

Backfiring

• ETC or speed limiter system malfunction

• Fouled spark plug or incorrect plug or plug gap

• Carburetion faulty - lean condition

• Exhaust system air leaks

• Ignition system faulty:

Spark plug cap cracked/broken

Ignition coil faulty

Ignition or kill switch circuit faulty

Ignition timing incorrect

Sheared flywheel key

• Poor connections in ignition system

• System wiring wet

• Valve sticking

• Air leaks in intake

• Lean condition

Cooling System

Overheating

• Low coolant level

• Air in cooling system

• Wrong type of coolant

• Faulty pressure cap or system leaks

• Restricted system (mud or debris in radiator fins or restriction to air flow, passages blocked in radiator, lines, pump, or water jacket)

• Lean mixture (restricted jets, vents, fuel pump or fuel valve)

• Fuel pump output weak

• Restricted radiator (internally or cooling fins)

• Water pump failure

• Cooling system restriction

• Cooling fan inoperative or turning too slowly

(perform current draw test)

• Ignition timing misadjusted

• Low oil level

• Spark plug incorrect heat range

• Faulty hot light circuit

• Thermostat stuck closed or not opening completely

• Possible loose or missing diverter inside radiator

Temperature Too Low

• Thermostat stuck open

Leak at Water Pump Weep Hole

• Faulty water pump mechanical seal (coolant leak)

• Faulty pump shaft oil seal (oil leak)

3.54