Polaris Scrambler 50 (2003), Predator 90 (2003), Scrambler 90 (2003), Sportsman 90 (2003) Service Manual (PN 9918068) – Chapter 2 Engine / Transmission / CVT
ENGINE
CVT System Exploded View
Secondary Spring Seat
Oil Seal
Bearing
Primary Drive
Cam Plate
Slider
Primary Sliding Sheave
Bolt
Circlip
Weight Roller
Compression Spring
Clip
Seal
Pin
Bushing
Clutch Spring Weight
Carrier Clutch
Clutch Cover
Nut
Nut
Secondary Fixed Sheave
OIl Seal
Claw Washer
Washer
Secondary Sliding Sheave
OIl Ring
O--ring
Bearing
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS
Fastener Torque
Carburetor
Adaptor
Crankcase 86 in.lbs (10 Nm)
Intake Manifold
Bolts
Cylinder Head
Nuts
Drive Clutch Nut 29 ft.lbs (39 Nm)
Driven Clutch Nut
Torque
Transmission
Cover Bolts
Flywheel 25 ft.lbs (34 Nm)
Oil Drain Bolt
(Transmission)
Oil Pump Bolts 43 in.lbs (5 Nm)
Primary Fixed Sheave
20 in.lbs (2.25 Nm)
108 in.lbs (12 Nm)
14 ft.lbs (19 Nm)
25 ft.lbs (34 Nm)
84 in.lbs (9.5 Nm)
14 ft.lbs (19 Nm)
Nut
One Way Clutch
Fan Housing 84 in.lbs (9.5 Nm)
Fan Bolts 84 in.lbs (9.5 Nm)
Stator Plate 84 in.lbs (9.5 Nm)
Starter Motor
Bolts
Spark Plug 11 ft.lbs (15 Nm)
84 in.lbs (9.5 Nm)
SPECIAL TOOLS
DESCRIPTION PART NUMBER
Crankshaft
Removal Tool
Flywheel Puller PA--45153
Oil Pump Drive
Gear Removal Tool
Crankcase
Separating Tool
NOTE:Special tools can be ordered by Polaris
Dealers only through SPX Corporation at (800)
328--6657.
0450697
0450699
0450700
2.2
ENGINE
ENGINE REMOVAL
REMOVE BODY PANELS
SCRAMBLER / PREDATOR
SPORTSMAN
2. Remove the air box and carburetor from the
chassis.
Air Box and Carburetor
3. Loosen and remove the drive chain from the drive
sprocket. Loosen the exhaust mounting bolts
from under the engine. Remove any other muffler
mountings from the engine.
1. To remove the engine from the chassis some body
panels have to be taken off the machine. Refer to
the Illustration above for removal of the proper
body panels. The Sportsman requires all of the
body panels to be removed. The Scrambler
requires the footrest and the muffler guard to be
removed.
Muffler Guard
REMOVE FOOTREST
Exhaust
4. Remove the fan cover.
2.3
ENGINE
5. Loosen the oil pump cable.
6. Remove the oil pump adjustment cable.
2. Perform checks on fluid levels, controls, and all
important areas on the vehicle as outlined in the
daily pre-ride inspection checklist.
Exhaust
1. Replace exhaust gaskets. Seal connections with
high temp silicone sealant.
2. Check to be sure all springs are in good condition.
Engine Break In Period
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 2 cycle engine 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.
ENGINE DISASSEMBLY
NOTE: It is not necessary to remove the kick drive
lever or components to remove the LH cover.
1. Remove cylinder air shroud and deflector. Remove
the kick arm assembly and the plastic case cover.
7. Loosen the engine mounting nuts. Carefully
support the engine and remove the engine
mounting bolts and spacer. Pull the engine from
the chassis.
Engine Mounting Bolts
ENGINE INSTALLATION
General Items
1. Install previously removed components in reverse
sequence using new gaskets, seals, and
fasteners where applicable.
2. Remove the air filter and the crankcase cover.
2.4
ENGINE
3. Remove the drive belt.
4. Remove the idle gear plate, two washers, and idle
gear from the pin shaft.
6. Remove the primary fixed sheave and washerclaw.
7. Remove the bushing, the primary sliding sheave,
and the cam plate assembly.
Primary Sheave
NOTE: There is one washer on the inside of the idle
gear and one washer on the outside of the idle gear.
5. Remove the nylon lock nut, the cone spring washer,
and the one way clutch from the crankshaft.
NOTE: When removing the primary sliding sheave
and the cam plate assembly, use two hands to hold
the cam plate and theprimary slidingsheave together.
This prevents the roller weights from falling out of the
assembly.
8. Carefully remove the starter one--way assembly.
2.5
ENGINE
9. Remove the washer and needle bearing.
Washer
Needle
Bearing
10. Remove the driven clutch assembly by removing
the O--ring and nut from the shaft. . Replace the
O-- ring as needed.
O--Ring
12. Remove the spring washer and nut from the shaft.
13. Remove the flywheel using flywheel puller.
Flywheel Puller
11. Remove the three phillips screws holding the fan
in place. Remove the fan.
Flywheel Puller
(PA--45153)
14. Scribe an alignment mark on the stator backing
plate and the crankcase for proper alignment
upon engine assembly. Remove stator assembly.
2.6
ENGINE
15. Remove the stator gasket, clean the area
thoroughly. Loosen and remove the oil pump.
The oil pump slides out in the forward direction.
OIl Pump
16. Use the oil pump drive gear removal tool to
remove the oil pump drive gear.
18. Remove the dowel pin from the crankshaft.
19. Remove the external circlip from the crankshaft.
Oil Pump Drive Gear Removal Tool:
(PN 0450699)
17. Remove the oil seal bracket.
NOTE: To ease disassembly, clean the grease out of
the oil pump chamber area and note the amount. That
same amount of grease is reinserted into the chamber
laterintheengineassembly.
20. Remove the circlip to disassemble the oil pump
gear.
OIl Pump
2.7
ENGINE
21. Remove the cylinder head nuts and remove the
cylinder head. Clean the cylinder head using
parts washer solvent.
NOTE: During reassembly use new gaskets.
22. Remove the cylinder and gaskets.
24. Remove the piston pin clip and the piston pin.
25. Remove the needle bearing from the piston pin
bore.
23. Make note of the orientation of the piston. There is
an arrow on the piston head pointing toward the
exhaust side.
Arrow
OIl Pump
26. Carefully remove the piston rings so no damage is
done to the ring lands. Discard the rings and
replace them with new rings.
2.8
ENGINE
27. Remove the intake manifold and reed valve
assembly. Replace all gaskets.
Crankcase Separation
28. Remove all of the bolts from the crankcase to split
the case.
30. Use the crankshaft removal tool to remove the
crankshaft.
Crankshaft Removal Tool:
(PN 0450697)
31. Remove the external snap ring on the output shaft
bearing and remove the oil seal. Replace the
seals or bearing as needed.
29. Use the crankcase separating tool to disassemble
the right and left crankcase halves.
Crankcase Separating Tool:
(PN 0450700)
32. Remove the external snap ring to remove the
crankshaft bearing.
2.9
ENGINE
TRANSMISSION SERVICE
NOTE: Engine removal is required to service
transmission components. Refer to beginning of
this chapter for removal instructions.
1. Drain the oil from the gear case.
Drain Plug
2. Remove the transmission cover and gasket.
3. Remove the washer and the driven clutch gear.
4. Remove the drive axle assembly. Inspect for signs
of wear.
Main Axle
Primary Drive Assy.
Primary Drive
Axle Assy.
5. Remove the bolt and washer to aid removal of the
bearing and the primary drive assembly.
Primary Drive Assy.
Bearing
Bolt
Washer
Transmission Cover
NUT
WASHER
DRIVE SPROCKET
CIRCLIP
BEARING
OIL SEAL
CIRCLIP
BEARING
DRIVE AXLE
ASSY.
BEARING
2.10
MAIN AXLE
WASHER
Drive Shaft (Transmission) Exploded View
ENGINE
Driveshaft (Transmission) Assembly
6. Install the drive axle assembly, washers, main axle
and primary axle. Refer to 2.10 for order of
assembly.
Main Axle Drive Axle Assy.
Primary Drive Assy.
7. Install the transmission cover gasket and install the
transmission cover while mating the splines
together.
Torque the bolts to specification.
excessive, resurfacing head or replacement is
needed.
Cylinder Head Warp
Service Limit:
.002
(0.05 mm)
Cylinder Inspection
1. Inspect the surface of the cylinder for warpage.
Clean all gasket residue completely from sealing
surface. Use a feeler gauge and straight edge.
Measure the gap six (6) different ways as shown
in illustration at left. Normal gap should be .002
(0.05 mm)or less. If gap isexcessive, resurfacing
cylinder or replacement is needed.
Transmission Cover Bolt Torque:
84 in.lbs. (9.5 Nm)
ENGINE COMPONENT
INSPECTION
Cylinder Head Inspection
1. Inspect the surface of the cylinder head for
warpage. Clean all gasket residue completely
from sealing surface. Use a feeler gauge and
straight edge. Measure the gap six (6) different
ways as shown in illustration at left. Normal gap
should be .002
(0.05 mm) or less. If gap is
Cylinder Warp
Service Limit:
.002
(0.05 mm)
2. Inspect the cylinder walls for damage or scoring.
The cylinder bore must be de-glazed whenever
new piston rings are installed. If cylinder wear or
damage is excessive, it will be necessary to
oversize the cylinder using a new oversize piston
2.11
and rings. See Honing to Oversize in this
chapter. Inspect cylinder for out of round.
Piston Inspection
1. Inspect the piston for scoring or cracks in piston
crown or pin area. Excessive carbon buildup below
the ring land is an indication of piston, ring, or
cylinder wear. If damage is excessive, replace
piston. Piston-to-cylinder clearance should not
exceed .0047
(15 mm) from bottom. Then measure inside
diameter of cylinder. The difference between these
measurements should not exceed .0047
mm).
(0.12 mm). Measure the piston 5/8
(0.12
ENGINE
Piston Ring Installed Gap
Service Limit:
.030
(0.75 mm)
Piston Pin Hole Inspection
1. Using a telescoping gauge or similar bore gauge,
measure the inside diameter of the piston pin hole
on both sides of the piston. Replace if diameter
exceeds .395
(10.03 mm)
Piston to Cylinder Clearance:
50 cc: .00138--.00177” (.035-- .045 mm).
90 cc: .00118--.00197” (0.03 -- .05 mm)
Piston Ring Installed Gap
2. Position piston ring 1/2
cylinder using the piston to push it squarely into
place. Measure installed gap with a feeler gauge
at both the top and bottom of the cylinder.
Replace rings if the installed end gap exceeds the
service limit.
5/8 (15 mm)
(1.3 cm) from the top of the
Piston Pin Hole
Service Limit:
.395
(10.03 mm)
HONING -- -- CYLINDER HONE
SELECTION &
Polaris recommends using only a rigid hone or arbor
honing machine which has the capability of
oversizing. Selecting a hone which will straighten as
well as remove material from the cylinder is very
important. Using a common spring loaded glaze
breaker for honing is never advised.
PROCEDURE
2.12
ENGINE
HONING TO OVERSIZE
CLEANING THE CYLINDER
AFTER
Piston Pin Inspection
HONING
NOTE:
Piston Pin
Service Limit:
.393
(9.980 mm)
Connecting Rod Inspection
2.13
Connecting Rod Small End
Service Limit
.553
(14.04 mm)
ENGINE
CRANKSHAFT RUNOUT
Reed Valve Inspection
Reed Valve Air Gap
Service Limit:
.015
(0.4 mm)
Crankshaft Alignment Fixture
(PN 2870710)
MAG Side
PTO Side
2.14
ENGINE
CVT SYSTEM DISASSEMBLY
1. Remove the drive belt.
2. Remove the nylon lock nut, the cone spring washer,
and the one way clutch from the crankshaft.
Primary Sheave
NOTE: When removing the primary sliding sheave
and the cam plate assembly, use two hands to hold
the cam plate and theprimary slidingsheave together.
This prevents the roller weights from falling out of the
assembly.
5. Remove the roller weights from the primary sliding
sheave. Check the rollers for wear and scoring.
3. Remove the primary fixed sheave and washerclaw.
Weight Rollers
6. Remove the driven clutch assembly by removing
the O--ring and nut from the shaft. Replace the
O-- ring as needed.
O--Ring
4. Remove the bushing, the primary sliding sheave,
and the cam plate assembly. Inspect the sheaves
for scoring, grooving, or abnormal wear.
2.15
ENGINE
CVT Driven Clutch Cover and Lining
1. Inspect the condition of the clutch cover. Measure
the inside diameter of the cover using a caliper.
The inner diameter service limit is 4.43
mm). Inspect the condition and diameter of the
lining. The service limit of the lining is .039
mm). If either of these measurements exceeds
the limit, replace the clutch cover.
.039 (1.0 mm)
Driven Clutch Cover Inner Diameter
Service Limit: 4.43
(112.5 mm)
(112.5
(1.0
the belt is .626
is less than the service limit, or if the belt is worn,
glazed or hourglassed, replace.
(15.9 mm). If the width of the belt
CVT Drive Belt Width
Service Limit
.626
(15.9 mm)
CVT REASSEMBLY
Driven Inner Lining
Service Limit: .039
Driven Compression Spring
2. Use a vernier caliper to check the length of the
compression spring. At full extension, the
measurement should be no less than 2.74
mm). If out of specification, replace the spring.
Driven Compression Spring
Service Limit:
2.74
1. Install the washer and needle bearing.
(1.0 mm)
Washer
(69.7
Needle
Bearing
2. Carefully install the starter wheel onto the
crankshaft.
Washer
(69.7 mm)
CVT Belt Inspection
1. Inspect the surface of the drive belt for uneven wear
or grease deposits. Using a vernier caliper,
measure the width of the belt. The service limit of
2.16
Needle
Bearing
ENGINE
3. Install the bushing, the primary sliding sheave, and
the cam plate assembly.
Primary Sheave
NOTE: When installing the primary sliding sheave
and the cam plate assembly, use two hands to hold
the cam plate and the primary sliding sheave together.
The weight rollers will fall out if the assembly is not
installed properly.
4. Install the primary fixed sheave and washer claw.
6. Install the inside washer, the idle gear, and the
outside washer onto the pin shaft.
7. Install the idle gear plate. Torque the bolts to
specification.
5. Install the nylon lock nut, the cone spring washer,
and the one way clutch onto the crankshaft.
Torque the drive clutch nut to specification.
Drive Clutch Nut Torque:
29 ft.lbs. (39 Nm)
Idle Gear Bolt Torque:
84 in.lbs. (9.5 Nm)
8. Install the driven clutch assembly,driven clutch nut,
and the O--ring
O--Ring
Driven Clutch Nut Torque:
24 ft.lbs. (34 Nm)
2.17
ENGINE
9. Install the drive belt.
ENGINE REASSEMBLY
NOTE: Be sure to reinstall all of the bearings, seals, and
retaining rings before the crankcase is reassembled.
Crankcase
1. Install a new output shaft oil seal and replace the
snap ring.
Oil Pump Installation
3. Install the dowel pin into the crankshaft.
4. Install the oil seal bracket.
2. Install the crankshaft in one of the crankcase
halves. Install a new crankcase gasket andinstall
the other side of the crankcase. Torque the
crankcase bolts to the specification and pattern.
Torque pattern
4
1
Crankcase Bolt Torque:
86 in.lbs. (10 Nm)
5. Carefully install the oil pump drive gear on the
inside of the MAG side of the crankcase.
6
2
3
5
2.18
ENGINE
6. Install the wave washer and then install the external
circlips. Install the dowel pin into the crankshaft.
Wave Washer
External Circlip
Crankshaft
7. Install the oil pump assembly. Install the oil pump
and torque to specification.
Oil Pump
Drive Gear
Pin
Stator Installation
9. Install a new stator gasket.
10. Install the stator. Use the alignment marks
previously made during the disassembly of the
stator. Torque the bolts to specification.
Oil Pump Bolt Torque
43 in.lbs. (5 Nm)
8. Refill the oil pump gear chamber with the same
amount of grease that was removed from the
chamber during disassembly.
Polaris All Season Grease (14 oz)
(PN 2871423)
Refill with grease.
Stator Mounting Bolt Torque:
84 in.lbs. (9.5 Nm)
Stator Trigger / Flywheel Gap:
.020-- .040” (.5--1.0 mm)
2.19
ENGINE
11. Install the flywheel and flywheel nut. Torque to
specification.
Flywheel Nut Torque:
25 ft.lbs. (34 Nm)
12. Install the new intake manifold gasket, reed valve
assembly, and intake manifold. Torque the intake
manifold to specifications.
13. Carefully install the new piston rings, so no
damage is done to the piston or ring lands.
Piston Installation
14. Install the needle bearing into the piston pin bore.
Intake Manifold Bolt Torque:
108 in.lbs. (12 Nm)
15. Install the piston pin and the piston pin clip.
NOTE: The piston pin clip gap should face up or down.
(3 o’clock or 9 o’clock position, see illustration)
Properly lubricate the rings and connecting parts
before installation.
NOTE: Make sure the arrow on the top of the piston
faces the same direction ( to exhaust side) during the
piston disassembly. Refer to Page 2.8.
2.20
ENGINE
16. Make sure cylinder surfaces are clean and free
from debris. Install the cylinder gasket, cylinder,
cylinder head gasket, and cylinder head. Torque
the cylinder head nuts to specification.
Cylinder Head Nut Torque:
14 ft.lbs. (19 Nm)
17. Install new spark plug. The spark plug gap should
be .024--.028” (.6--.7 mm).
19. Install the fan. Torque the fan bolts to specification.
Fan Bolt Torque:
84 in.lbs. (9.5 Nm)
20. Install a new crankcase cover gasket, grommets,
and crankcase breather tube. Install the air filter
and the crankcase cover. Torque the crankcase
bolts to specifications.
Starter Wheel Installation
18. Install the washer and needle bearing. Carefully
install the starter wheel onto the crankshaft.
Washer
Needle
Bearing
Crankcase Cover Bolt Torque:
84 in.lbs. (9.5 Nm)
21. Install the cylinder air shroud and deflector. Install
the plastic crankcase cover.
2.21
ENGINE
22. Install the kick crank assembly onto the kick shaft.
23. Carefully install the engine into the chassis. Secure
the engine with the engine mounting bolts.
Engine Mounting Bolts
25. Install the fan cover.
26. Connect the exhaust pipe to the engine and frame
mounting areas.
24. Connect the oil cable to the oil pump. Tighten the
cable.
27. Install the air box and carburetor.
Air Box and Carburetor
28. Install the body panels.
2.22
ENGINE
KICK START ASSEMBLY
NOTE: This procedure is used to re--wind the kick
start spring if the spring or any related components
are disassembled for service. It is not necessary to
remove the kick start lever or kick drive
components to remove the engine cover.
1. Secure cover lightly in a vise as shown. Protect the
surface of the cover with a shop towel.
3. Grease and install the bushing in the kick shaft
boss.
4. Install the kick shaft as shown, with the edge of the
gear resting on the spring hook post (A). Grasp
the spring firmly with duckbill orneedle nose pliers
between the inner and outer spring coils. Wind
the spring approximately 225 degrees
counter--clockwise, while also rotating the gear
counter--clockwise into final position.
2. Install the spring as shown with the hook (A)
positioned on post. Note the spring tab (B). The
tab must be pre--wound approximately 5/8 turn
(about 225 degrees) to point C in order to install
the kick shaft/gear assembly.
A
A
5. Push the shaft/gear assembly in and release the
spring. The tab should be located against the
edge of the gear as shown (A).
B
C
A
2.23
ENGINE
6. Release the cover from the vise. Turn the cover
over while holding the spring and shaft assembly
in place, and install the washer.
7. Install the snap ring.
2. Remove the idle gear plate, two washers, and idle
gear from the pin shaft.
NOTE: There is one washer on the inside of the idle
gear and one washer on the outside of the idle gear.
3. Remove the washer and needle bearing. Carefully
remove the starter wheel from the crankshaft.
Washer
8. Install the kick pinion with the end of the drag spring
(A) engaged in the slot (B).
A
B
STARTER DRIVE ONE--WAY
INSPECTION
1. Remove the CVT cover, belt and drive clutch
components to gain access to the one--way drive.
Needle
Bearing
4. To disassemble the one--way assembly, remove
the three phillips screws from the starter wheel.
Inspect components for signs of wear or sticking.
Replace any components that interfere with
correct operation.
Weight Rollers
NOTE: Use caution when disassembling the starter
wheel, the starter wheel contains springs and pins
2.24
ENGINE
that easily come out of place. Uponassembly, do not
lubricate the one way rollers with heavy grease,
this will cause the one--way drive to
5. Inpect the washer and needle bearing. Replace if
any roughness or wear is present.
Washer
Needle
Bearing
6. To reinstall the starter drive one--way, reverse the
procedures.
TROUBLESHOOTING
Spark Plug Fouling
Spark plug cap loose or faulty
Choke plunger sticking or
inoperative
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
clips)
Loose jets in carburetor or calibration
incorrect for altitude/temperature
Incorrect float level setting
CVT system calibrated incorrectly/
components worn or mis-adjusted
Fuel quality poor (old) or octane too
high
Low compression
Plugged exhaust
Weak ignition (loose coil ground,
faulty coil, stator, or ETC switch)
ETC switch mis-adjusted
malfunction.
as
Restricted air filter (main or
pre-cleaner) or breather system
Improperly assembled air intake
system
Restricted air breather system
Oil contaminated
Engine Turns Over But Fails to Start
No fuel
Dirt in fuel line or filter
Fuel will not pass through fuel valve
Tank vent plugged or pinched
Carb starter circuit plugged
Engine flooded
Low compression (high cylinder
leakage)
No spark (Spark plug fouled)
ignition component failure
Safety switches malfunctioning
(Ignition, Kill, Brake--to--start)
Electrical malfunction
Engine Does Not Turn Over
Dead battery
Starter motor does not turn
Engine seized, rusted, or
mechanical failure
Safety switches malfunctioning
(Ignition, Kill, Brake--to--start)
Engine Runs But Will Not Idle
Restricted carburetor pilot system
Carburetor misadjusted
Low compression
Airbreatherrestricted
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
Carburetor slide sticking, damaged
Incorrect ignition timing
Restricted exhaust system
Engine Has Low Power
2.25
ENGINE
Spark plug fouled
Cylinder, piston, ring, or reed wear or
damage (check compression)
CVT not operating properly
Restricted exhaust muffler
Carburetor slide sticking or 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
Worn rings, piston, or cylinder
Restricted breather
Air filter dirty or contaminated
Oil pump misadjusted or faulty
Low Compression
Cylinder head gasket leak
Cylinder or piston worn
Piston rings worn, leaking, broken,
or sticking
Reeds broken or bent
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
Reeds broken or bent
Air leaks in intake or crankcase
Lean condition
2.26
Overheating
Restricted air flow (mud or debris in
cooling fins causing restriction to air
flow, accident damage)
Lean mixture (restricted jets, vents,
fuel pump or fuel valve)
Fuel pump output weak causing
lean condition
Electrical malfunction
Internal Mag--side fan damaged or
plugged with debris.
Ignition timing misadjusted
Spark plug incorrect heat range
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