Page 1
9. DRIVE AND DRIVEN PULLEYS
9-0
Mongoose/KXR 90/50
9
DRIVE AND DRIVEN PULLEYS
SERVICE INFORMATION ...........................................................9-2
LEFT CRANKCASE COVER/KICK STARTER..............................9-4
DRIVE PULLEY ..........................................................................9-7
CLUTCH/DRIVEN PULLEY.........................................................9-9
9
Page 2
9. DRIVE AND DRIVEN PULLEYS
9-1
Mongoose/KXR 90/50
Page 3
9. DRIVE AND DRIVEN PULLEYS
9-2
Mongoose/KXR 90/50
SERVICE INFORMATION
GENERAL INSTRUCTIONS
• The drive pulley, clutch and driven pulley can be serviced with the engine installed in the frame.
• Avoid getting grease and oil on the drive belt and pulley faces. Remove any oil or grease from
them to minimize the slipping of drive belt and drive pulley.
SPECIFICATIONS (Mongoose/KXR 90)
Item
Standard (mm)
Service Limit (mm)
Movable drive face bushing I.D.
23.989_ 24.052
24.06
Drive face collar O.D.
23.96_ 23.974
23.94
Drive belt width
17.5
16.5
Clutch lining thickness
4.5
2.0
Clutch outer I.D.
112.0_ 112.2
112.5
Driven face spring free length
145.5
137.5
Driven face O.D.
33.965_ 33.985
33.94
Movable driven face I.D.
34.000_ 34.025
34.06
Weight roller O.D.
15.92_ 16.08
15.4
SPECIFICATIONS (Mongoose/KXR 50)
Item
Standard (mm)
Service Limit (mm)
Movable drive face bushing I.D.
20.036_ 20.085
20.6
Drive face collar O.D.
20.01_ 20.025
19.98
Drive belt width1817.5
Clutch lining thickness
3.5
1.0
Clutch outer I.D.
107_ 107.2
107.5
Driven face spring free length
98.1
92.8
Driven face O.D.
33.965_ 33.985
33.94
Movable driven face I.D.
34.0_ 34.025
34.06
Weight roller O.D.
15.92_ 16.08
15.4
Page 4
9. DRIVE AND DRIVEN PULLEYS
9-3
Mongoose/KXR 90/50
TORQUE VALUES
Drive face nut 5.5_ 6.5kgf-m (Mongoose/KXR 90)
3.5_ 4.5kgf-m (Mongoose/KXR 50)
Clutch outer nut 3.5_ 4.5kgf-m
Drive plat nut 5.0_ 6.0kgf-m
SPECIAL TOOLS
Universal holder E017 Clutch spring compressor E034
Bearing puller E037 Oil seal and bearing install E014
TROUBLESHOOTING
Engine starts but motorcycle won’t move Lack of power
• Worn drive belt • Worn drive belt
• Broken ramp plate • Weak driven face spring
• Worn or damaged clutch lining • Worn weight roller
• Broken driven face spring • Fouled drive face
Engine stalls or motorcycle creeps
• Broken clutch weight spring
Page 5
9. DRIVE AND DRIVEN PULLEYS
9-4
Mongoose/KXR 90/50
LEFT CRANKCASE COVER/KICK
STARTER
REMOVAL
Remove left foot board. (See page 2-7)
Remove the eight left crankcase cover bolts
and left crankcase cover.
Remove the gasket and dowel pins.
KICK STARTER
DISASSEMBLY
Remove the kick lever from the kick starter
spindle.
Remove the circlip and washer from the kick
starter spindle.
Remove three bolts at the kick starter spindle
cover, then remove kick starter spindle cover.
Gently turn the kick starter spindle to remove
the starter driven gear together with the
friction spring.
Remove the kick starter spindle and return
spring from the left crankcase cover.
Remove the kick starter spindle bushings.
Return Spring
Kick Starter Spindle
Friction Spring
Starter Driven Gear
Kick Starter Spindle
Circlip
Washer
Bolts
Left Crankcase Cover
Bolts
Kick Starter Spindle
Cover
Use specified genuine parts for
replacement.
＊
Page 6
9. DRIVE AND DRIVEN PULLEYS
9-5
Mongoose/KXR 90/50
INSPECTION
Inspect the kick starter spindle and gear for
wear or damage.
Inspect the return spring for weakness or
damage.
Inspect the kick starter spindle bushings for
wear or damage.
Inspect the starter driven gear for wear or
damage.
Inspect the friction spring for wear or
damage.
Inspect the kick starter spindle and starter
driven gear forcing parts for wear or damage.
ASSEMBLY
Install the kick starter spindle bushing and
return spring onto the left crankcase cover.
Install the kick starter spindle.
Starter Driven Gear Shaft Forcing Part
Friction Spring
Starter Driven Gear
Spindle
Return Spring
Plastic Bushing
Spindle Bushing
Kick Starter Spindle Forcing Part
Kick Starter Spindle
Return Spring
Apply grease on to the bushing and
spindle teeth.
＊
Page 7
9. DRIVE AND DRIVEN PULLEYS
9-6
Mongoose/KXR 90/50
Install the starter driven gear and friction
spring onto the left crankcase cover as the
figure shown.
Install the kick starter spindle cover and
tighten three bolts.
First install the washer and then install the
circlip.
Install the kick lever.
LEFT CRANKCASE COVER
INSTALLATION
First install the dowel pins.
Install the gasket.
Install the left crankcase cover and tighten the
eight left crankcase cover bolts diagonally.
Washer
Left Crankcase Cover
Starter Driven Gear
Friction Spring
Circlip
Dowel Pins
Bolts
Kick Starter Spindle Cover
Apply grease on to the driven gear shaft.
＊
Page 8
9. DRIVE AND DRIVEN PULLEYS
9-7
Mongoose/KXR 90/50
DRIVE PULLEY
REMOVAL
Remove the left crankcase cover. (Refer to the
“LEFT CRANKCASE COVER
REMOVAL” section in the chapter 9)
Hold the drive pulley using a universal
holder and remove the drive face nut and
washer.
Remove the drive pulley.
Universal Holder E017
Remove the movable drive face assembly and
drive pulley collar.
DISASSEMBLY
Remove the ramp plate.
Remove the six weight rollers.
Drive Pulley Collar
Drive Face
Ramp Plate
Roller
Special
Drive Pulley
Nut
Starting Ratchet
Universal Holder
Page 9
9. DRIVE AND DRIVEN PULLEYS
9-8
Mongoose/KXR 90/50
INSPECTION
Check each weight roller for wear or damage.
Measure each weight roller O.D.
Service Limit: 15.4mm replace if below.
Measure the movable drive face bushing I.D.
Service Limit:
Mongoose/KXR 90: 24.06mm over
Mongoose/KXR 50: 20.06mm over
ASSEMBLY
Install the weight rollers into the movable
drive face.
Install the ramp plate.
Check the drive pulley collar for wear or
damage.
Measure the O.D. of the drive pulley collar
sliding surface.
Service Limit:
Mongoose/KXR 90: 23.94mm below
Mongoose/KXR 50: 19.98mm below
INSTALLATION
Install the drive pulley face assembly and
collar.
Install the drive pulley, starting ratchet and
nut.
Torque:
Mongoose/KXR 90: 5.5_ 6.5kgf-m
Mongoose/KXR 50: 3.5_ 4.5kgf-m
l When installing the drive pulley face,
compress it to let the drive belt move
downward to the lowest position so that
the drive pulley can be tightened.
l Do not get oil or grease on the drive belt
or pulley faces.
°Ø
Page 10
9. DRIVE AND DRIVEN PULLEYS
9-9
Mongoose/KXR 90/50
CLUTCH/DRIVEN PULLEY
REMOVAL
Remove the left crankcase cover. (Refer to the
“LEFT CRANKCASE COVER
REMOVAL” section in the chapter 9)
Remove the drive pulley. (Refer to the
“DRIVE PULLEY REMOVAL” section in
the chapter 9)
Hold the clutch outer with the universal
holder, then remove the clutch outer nut and
clutch outer.
Universal Holder E017
Remove the clutch/driven pulley and drive
belt.
DRIVE BELT INSPECTION
Check the drive belt for cracks, separation or
abnormal or excessive wear.
Measure the drive belt width.
Service Limit:
Mongoose/KXR 90: 16.5mm
Mongoose/KXR 50: 17.5mm
CLUTCH OUTER INSPECTION
Inspect the clutch outer for wear or damage.
Measure the clutch outer I.D.
Service Limit:
Mongoose/KXR 90: 112.5mm
Mongoose/KXR 50: 107.5mm
Nut
Universal Holder
Clutch/Driven Pulley
Drive Belt
Clutch Outer
Special
Use specified genuine parts for
replacement.
°Ø
Page 11
9. DRIVE AND DRIVEN PULLEYS
9-10
Mongoose/KXR 90/50
CLUTCH/DRIVEN PULLEY
DISASSEMBLY
Hold the clutch/driven pulley assembly with
the clutch spring compressor.
Clutch Spring Compressor E034
Set the clutch spring compressor in a vise and
remove the clutch drive plate nut.
Loosen the clutch spring compressor and
disassemble the clutch/driven pulley assembly.
Remove the seal collar.
Pull out the three guide roller pins and guide
rollers. Remove the movable driven face from
the driven face.
Clutch Spring Compressor
Lock Nut Wrench, 39mm
Movable Driven Face
Guide Roller Pins
Dust Seal
Special
Be sure to use a clutch spring
compressor to avoid spring damage.
°Ø
Seal Collar
Page 12
9. DRIVE AND DRIVEN PULLEYS
9-11
Mongoose/KXR 90/50
Measure the clutch lining thickness.
Service Limit:
Mongoose/KXR 90: 1.5mm replace if below
Mongoose/KXR 50: 1.0mm replace if below
INSPECTION
Measure the driven face spring free length.
Service Limit:
Mongoose/KXR 90: 137.5mm below
Mongoose/KXR 50: 92.8mm below
Check the driven face for wear or damage.
Measure the driven face O.D.
Service Limit: 33.94mm below
Page 13
9. DRIVE AND DRIVEN PULLEYS
9-12
Mongoose/KXR 90/50
Check the movable driven face for wear or
damage.
Measure the movable driven face I.D.
Service Limit: 34.06mm over
DRIVEN PULLEY FACE BEARING
REPLACEMENT
Drive the inner needle bearing out of the
driven pulley face.
Remove the snap ring and drive the outer
bearing out of the driven face.
Bearing Puller E037
Apply grease to the outer bearing.
Drive a new outer bearing into the driven face
with the sealed end facing up.
Seat the snap ring in its groove.
Apply grease to the driven face bore areas.
Press a new needle bearing into the driven
face.
Oil Seal And Bearing Install E014
Inner Needle Bearing
Outer Bearing
Discard the removed bearing and replace
with a new one.
°Ø
Discard the removed bearing and replace
with a new one.
°Ø
Snap Ring
Snap Ring
Outer Bearing
Inner Needle Bearing
Special
Pack all bearing cavities with proper
grease.
Specified grease: Heat resistance 230°C
°Ø
Special
Page 14
9. DRIVE AND DRIVEN PULLEYS
9-13
Mongoose/KXR 90/50
CLUTCH DISASSEMBLY
Remove the circlips to disassemble the clutch.
CLUTCH / DRIVEN PULLEY ASS EMBLY
Circlip
Clutch Lining
Keep grease off the clutch linings.
°Ø
Page 15
9. DRIVE AND DRIVEN PULLEYS
9-14
Mongoose/KXR 90/50
Install the damper rubbers on the drive plate
pins.
Install the clutch weights/shoes and clutch
springs.
Set the circlips in the groove.
Clean the driven pulley faces and remove any
grease from them.
Install the oil seal onto the moveable driven
face.
Apply grease onto the Oil seal and install
them onto the moveable driven face.
Install the movable driven face onto the
driven face.
Apply grease to the guide rollers and guide
roller pins and then install them into the holes
of the driven face.
Install the seal collar.
Remove any excessive grease.
Set the driven pulley assembly, collar (OFF
ROAD), driven face spring and clutch
assembly onto the clutch spring compressor.
Compress the clutch spring compressor and
install the drive plate nut.
Set the clutch spring compressor in a vise and
tighten the drive plate nut to the specified
torque.
Torque: 5.0_ 6.0kgf-m
Clutch Spring Compressor E027
Be sure to clean the driven face off any
grease.
°Ø
Align the flat surface of the driven face
with the flat on the clutch drive plate.
°Ø
Be sure to use a clutch spring
compressor to avoid spring damage.
°Ø
Special
Clutch Spring Compressor
Lock Nut Wrench, 39mm
Driven Pulley
Collar (OFF ROAD)
Spring
Clutch
Nut
Page 16
9. DRIVE AND DRIVEN PULLEYS
9-15
Mongoose/KXR 90/50
INSTALLATION
Install the clutch/driven pulley and driven belt
onto the drive shaft.
Install the clutch outer.
Hold the clutch outer with the universal
holder.
Install and tighten the clutch outer nut.
Torque: 3.5_ 4.5kg-m
Universal Holder E017
Keep grease off the drive shaft.
°Ø
Special
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