um UXPW125 User manual

UXPW125 ENGINE SERVICE MANUAL
AND EFI DIAGNOSTIC

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
- 2 -
INDEX
1、MAIN TECHNICAL PARAMETERS
2、GENERAL MAINTENANCE
3、LUBRICATION SYSTEM
4、CYLINDER HEAD PARTS MAINTENANCE
5、CYLINDER BLOCK AND PISTON
6. RIGHT COVER/ CLUTCH/ BALANCING GEAR/ GEARSHFT
7. LEFT COVER/ STARTING MOTOR SYSTEM/ MAGNETO
8.CRANKCASE (EXTRACTION AND INSTALLATION)
9. EFI DIAGNOSTIC SYSTEM RENEGADE II 125 SERIES

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
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MAIN TECHNICAL PARAMETERS
Item
Specification
Engine
Model number
UXPI 125
Type
Single-cylinder, water-cooling,
four-stroke, SOHC
Bore X stroke
Φ52.4×57.8mm
Piston Displacement
124.6 C.C.
Compression ratio
11：1
Valve
Timing
In
Open
（ 5°BTDC）
Close
（37°ABDC）
Out
Open
（50°BBDC）
Close
（3°ATDC）
Max. power
9(1 ±5%)kW/9500(1 ±5%)rpm
Max. torque
10(1 ±5%)N.m. /8000(1 ±5%)rpm
Idle speed
1400±100 r /min
Transmission
System
Clutch
Manual wet multi-plate
Transmission
Constant mesh, two-stage transmission,
5-speed gearshift
Gearshift method
1-N-2-3-4-5
Primary reduction ratio
3.35（67/20）
Gear ratio
1st
3.077（40/13）
2nd
1.789(34/19)
3rd
1.304(30/23)
4th
1.091(24/22)
5th
0.929(26/28)

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
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1.1 Maintenance Parameters：
Item
S tandard
Service Limit
Engine oil
Specification
SJ 10W/40
1.2 L
Capacity
when filter is not
removed
1 L
when filter is removed
1.1 L
when engine is completely
dry
1.2 L
Valve
Clearance
Inlet
0.04-0.06mm
0.10mm
Exhaust
0.04-0.06mm
0.15mm
Spark Plug
Standard
CPR8EA-9(NGK)
Long hours at high RPM
CPR9EA-9(NGK)
Electrode clearance
(0.8-1.0) mm
Engine idle speed
1400±100rpm
1.2 Cylinder Head and Valves unit：mm
Item
Standard
Service Limit
Valve Clearance
Inlet
0.04-0.06
Exhaust
0.04-0.06
Valve Stem Diameter
Inlet
4.975-4.990
4.92
Exhaust
4.955-4.970
4.90
Valve Guide Internal Diameter
Inlet
Exhaust
5.000-5.012
5.04
Valve/Valve Guide Clearance
Inlet
0.010-0.037
0.07
Exhaust
0.030-0.057
0.09
Width of valve sealing strip
0.9-1.1
1.5
Valve Spring Free Length
In
38.5-39.5
37.8
Outer
41.5-42.5
40.8
Rocker arm hole diameter
10.000-10.012
10.1
Rocker shaft diameter
9.973-9.984
9.91
Clearance between Rocker arm and rocker shaft
clearance
0.016-0.039
0.10
Camshaft
Cam Height
Inlet
31.830-31.930
31.8
Exhaust
31.559-31.659
31.5

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
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1.3 Cylinder and Piston unit: mm
Item
S tandard
Service Limit
Cylinder
Inner diameter of cylinder
Φ52.400～φ52.410
Φ52.5
Cylindricity
0.004
0.10
Planeness of cylinder face
0.03
0.10
Piston, Piston
Rings and
Piston Pin
Outer diameter of piston
Φ52.38～φ52.39
Φ52.3
Inner diameter of piston pin hole
φ14.002～14.008
φ14.04
Closure clearance of
piston ring
Top
0.1～0.25
0.35
Second
0.15-0.30
0.4
Oil
0.2～0.7
0.85
Piston Ring/Groove
Clearance:
Top
0.02～0.06
0.10
Second
0.02～0.06
0.10
Piston/Cylinder Clearance
0.01～0.03
0.07
Outer diameter of piston pin
φ13.994～φ14
φ13.96
Clearance between piston pin and piston
pin hole
0.002～0.014
0.04
Small End of
Connecting
Rod
Inner diameter
φ14.015～14.028
φ14.06
Clearance between small end of
connecting rod and piston pin
0.015～0.03
0.10

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
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1.4 Clutch unit：mm
Item
Standard
Service Limit
Clutch
Clutch Spring Free Length
41.1-41.9
40
Friction Plates Thickness
2.92-3.08
2.6
flatness of clutch driven plate
0.20
Driven gear inner hole diameter
Φ23.000 ～φ23.021
φ23.08
Shaft sleeve
Collar diameter
Φ22.960～φ22.975
Φ22.93
Bushing aperture
Φ16.990～φ17.008
φ17.04
The spindle diameter
Φ16.966～φ16.984
Φ16.95
1.5 Driver Train unit：mm
Item
S tandard
Service Limit
Crankshaft,
Connecting Rods
Connecting Rod
Big End:
Radial Clearance
0～0.008
0.03
Side Clearance
0.1～0.35
0.5
Crankshaft Run out
0.03
0.08
Fork
Outer diameter of fork shaft
Φ9.966～φ9.984
Φ9.93
Inner diameter of fork
Φ10.000～φ10.018
φ10.05
Shift Fork Thickness
4.93～5.00
4.5
Transmission
Gears inner hole
diameter
M4
Φ20.000～φ20.021
Φ20.04
M5
Φ20.000～φ20.021
Φ20.04
C1
Φ20.500～φ20.521
Φ20.55
C2
Φ23.000～φ23.021
Φ23.04
C3
Φ23.025～φ23.046
Φ23.06
Bushing external
diameter
M4
Φ19.959～φ19.980
Φ19.93
M5
Φ19.959～φ19.980
Φ19.93
C1
Φ20.459～φ20.480
Φ20.41
C2
Φ22.984～φ23.005
Φ22.95
Bushing internal
diameter
M4
Φ17.000～φ17.018
φ17.04
C1
Φ17.000～φ17.018
φ17.04
C2
Φ20.000～φ20.021
Φ20.04
Shaft diameter
M4
φ16.966～φ16.984
φ16.93
C1
φ16.966～φ16.984
φ16.93
C2
φ19.974～φ19.987
φ19.94
C3
φ19.979～φ20.000
φ19.95

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
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GENERAL MAINTENANCE
2.1. ENGINE MAINTENANCE CYCLE .........................................................................................................- 8 -
2.2. ENGINE MAINTENANCE STANDARDS................................................................................................- 8 -
2.3. TORQUE STANDARS....................................................................................................................- 8 -
2.4. SPARK PLUG MAINTENANCE........................................................................................................- 9 -
2.5. VALVE CLEARANCE ADJUSTMEN-....................................................................................................- 10 -
2.6. OIL LEVEL INSPECTION....................................................................................................................- 12 -
2.7. OIL CHANGE ....................................................................................................................................- 13 -

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
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2.1 Engine Maintenance Cycle
Cycle
Maintenance
Travel
Inspection
T
Travel Kms（×1000 Km）
1
3
6
9
12
Spark Plug
I
I
R
I
Valve Clearance
I
I
I
I
I
Engine Oil
I
R
R
R
R
R
Fuel Filter
R
R
R
R
R
Oil Strainer
C
C
Oil Filter
R
R
R
R
R
Idle Speed
I
I
I
I
I
I: Inspect, clean, adjust, lubricate or replace if necessary. C: Clean R: Replace
IMPORTANT NOTE: to guaranty the perfect function of fuel injection system, the fuel filter must
be changed every 3000 Km, as is specified in the table; and the fuel pump filter changed every
10000 km.
2.2 Engine Maintenance Standards
Item
S tandard
Service Limit
Engine oil
Specification
SJ 10W/40
1.2L
Capacity
Filter is not removed
1
Oil filter removed
1.1L
Dry Engine
1.2
Valve Clearance
Inlet
（0.04-0.06）mm
0.10mm
Exhaust
（0.04-0.06）mm
0.15mm
Spark Plug
Standard
CPR8EA-9(NGK)
High RPM extreme use
CPR9EA-9(NGK)
Electrode clearance
(0.8-1.0) mm
Engine Idle Speed
1400±100rpm
2.3. Torque Standards
Spark Plug：16 N.m.
Oil Discharge Bolt：24 N.m.
Engine Oil Cap Bolt：10 N.m.
Head Cap (cylinder head) Bolts：10 N.m.
Valve Clearance Nuts：14 N.m.

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
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2.4 Spark Plug Maintenance
Suggested Spark Plug Reference
Standard Use
CPR8EA-9(NGK)
High RPM Extreme Use
CPR9EA-9(NGK)
Note:
Using wrong spark plug specification
can damage the engine.
If the lateral and center electrode have erosion or
covered with accumulation of carbon, the spark plug
shall be cleaned or replaced.
The clearance of spark plugs shall be: (0.8-1.0）mm
Assembly torque of spark plug: 16 N.m.
Note:
A spark plug that does not is properly tighten
may cause damage to the engine. If the spark
plug is too loose, it may cause damage to the
piston. If the spark plug is too tight, it may
cause damage of the thread.

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
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2.5. Valve Clearance Adjustment
Too large valve clearance will result in noise and
ultimately in damage of engine. Too small valve
clearance or no clearance will result in that valves are
not closed tightly, thus causing valve damage and
power loss of the engine.
Remove caps with big and small view hole,
respectively, from engine.
Turn crankshaft until the engine is at timing position
(Mark line “T” on rotor of magneto is aligned with
center of view hole.)
Remove upper cover of cylinder head
(refer to 4.2 section)
Check Valve Clearance
Note:
The inspection and adjustment of the valve
clearance shall be checked and adjusted under
the “cold machine” condition of the engine.
Clearance will change as the engine
temperature rises.
Adjust Valve Clearance
Inlet and exhaust valve clearance: (0.04-0.06) mm
Tightening torque of adjusting nut: 14N.m
Inspect for distortion or damage at the O-ring View
hole cover, if exist any, the O-ring needs to be
replaced; after the new O-ring is replaced, apply a
proper amount of lubricant on the new O-ring before
assembling.

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
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Tighten caps of large and small view holes, respectively.
Install upper cover of cylinder head, and check the
engine for leakage.

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
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2.6. Oil level inspection
2.6.1 Check engine oil before driving every day.
2.6.2 Oil level must be between the upper and
lower lines of the oil level gauge.
2.6.3 Start the engine and let it idle for
3-5minutes.
2.6.4 2-3minutes after, stopping the engine,
support the vehicle using the main stand
on firm level ground, remove oil level
gauge, wipe it up and reinsert it. Then put
it out again to check oil level, which must
be kept between the upper and lower
limits on the gauge. Make sure there are
no oil leaks.
2.6.5 If is necessary, please add oil until the
level reaches upper limit on the gauge.
Never exceed the upper limit.
Reload the oil ruler and inspect the oil leakage

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
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2.7 Oil change
Engine oil quality is the main factor, affecting engine
service life. Change the engine oil as specified in the
maintenance schedule (refer to 2.1 section).
when running in very dusty conditions, oil changes should
be performed more frequently than specified in the
maintenance schedule.
Please dispose the used engine oil in conditions that
doesn’t contaminate the environment, we suggest you
take it in a sealed container to your local recycling center
or service station for reclamation. Please do not throw it
in the trash or pour it on the ground or down a drain.
Prolonged used oil exposure on the skin can lead to skin
cancer. Although this is unlikely, unless you handle used
oil at daily, is still advisable to wash your hands with soap
and water as soon as possible after handling used oil.
Changing the oil filter requires a torque wrench. If you do
not have it or the necessary skill to do the task, we
recommend you visit your UM dealer to perform this
service.
Change the engine oil with the engine at normal
operating temperature and the vehicle stand on its side
stand to assure complete and fast draining.
2.7.1 Place a drain pan under the crankcase.
2.7.2 To drain off the oil, remove the oil level gauge, oil
drain bolt and sealing washer.
2.7.3 Remove bolt from filter cover to remove the filter
cover, sealing washer and filter.
2.7.4 Check if oil path on the filter cover is clear, sealing
washer is in good condition; otherwise, replace the
washer with a new one
2.7.5 Install the new oil filter with the “DL” mark facing
out.
Note
Use only the UM genuine oil filter or a filter of
equivalent quality specified for your model.

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
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using the wrong UM filter or a non-UM filter which is
not of equivalent quality may cause engine damage.
2.7.6 Install locating pin. Fix a new sealing washer on
the filter cover, then install the cover on the right
cover.
2.7.7 Install and tighten the filter cover bolt
Oil filter cover bolts torque: 12N.m
2.7.8 If necessary, clean the oil screen, Remove the
right cover. (refer to 6.5 section for extraction of right
cover). Take out oil screen to clean strange elements
from it. Then reinstall it according to direction shown
in the figure.
Note
Strange elements on the oil screen can be
used to determine preliminarily if there is
abnormal damage on the engine. If too
much metallic dust is detected, the
engine shall be subject to inspection.
The oil screen shall not be cleaned with
gasoline or other solvents that may
damage rubber.
Reinstall the right cover (refer to 6.5 section).
2.7.9. Check if drain bolt and sealing washer are in
good condition. Replace the drain bolt and sealing
washer, then tighten the bolt. Always replace the
sealing washer whenever renewing the engine oil.
Tightening torque of engine oil drain bolt: 24N.m
2.7.10. Fill the engine with oil of equivalent grade
according to requirements of maintenance
(SJ/10W-40); Reinstall the oil level gauge.
2.7.11. Start the engine and let it idle for 3-5minutes.
2-3minutes after stopping the engine, check that oil
level is at the upper level mark in the inspection
window with the vehicle upright on firm level ground.
2.7.12. Confirm the engine is free of any leakage.

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
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LUBRICATION SYSTEM
3.1 Lubrication system (schematic diagram)..........................................................................................- 16 -
3.2 Lubrication system (technical specifications)...................................................................................- 17 -
3.3 Troubleshooting: ..............................................................................................................................- 17 -
3.4 Oil pump (extraction and installation) .............................................................................................- 18 -

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
- 16 -
3.1 Lubrication system (schematic diagram)

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
- 17 -
3.2 Lubrication system (technical specifications)
Unit: mm
Item
Standard
Service Limit
Engine oil
Specification
SJ 10W/40
Capacity
when filter is not removed
1L
when filter is removed
1.1L
when engine is completely dry
1.2L
Oil pump
Backlash between outer rotor and pump body
0.28
Backlash between inner and outer rotors
0.20
Axial clearance between rotor and pump body
0.15
Requirements of tightening torque
Fastening bolt of oil pump: 10N.m
Screw on cover plate of oil pump: 3N.m
3.3 Troubleshooting
Name of
component
Type of damage
Symptom of
component
Symptom of
engine
Remedy
Oil pump
Excessive wear of inner and
outer rotors of oil pump
Oil is not
pumped freely
or no oil is
pumped.
Engine overheats
and is
insufficient in
power.
Replace the oil
pump.
Oil screen
Too much foreign matters on
it or clogged.
Clean the
screen
Oil filter
Too much foreign matters on
it or clogged.
Replace the oil
filter.
Lubrication
system
Clogged passage
Clean and
unblock the oil
path.

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
- 18 -
3.4 Oil pump (extraction and installation)
3.4.1. Oil pump dismantle
3.4.1.1 Dismantle right cover (refer to 6.5 section),
then remove circlip and take out gears of oil
pump.
3.4.1.2 Take out the pin and remove fastening bolt
of oil pump. Take out oil pump.
3.4.1.3 Remove the two location pins.
3.4.2. Oil pump disassembly
3.4.2.1. Remove set screw from cover plate.

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
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3.4.2.2. Remove the inner rotor, pin and pin shaft from oil
pump.
3.4.2.3. Take out outer rotor of oil pump and clean the
components disassembled thoroughly.
3.4.3. Check of oil pump
Note:
When checking oil pump, turn the rotor to
measure it at multiple points, so as judge it if
its wear is beyond service limit.
If wear measured at any point is beyond the
service limit, the oil pump shall be replaced
with a new one.
3.4.3.1. Assemble inner and outer rotors, pin shaft, pin
of the oil pump.
Check side clearance between outer rotor and casing
Service limit
0.28mm

UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
- 20 -
3.4.3.2. Check fit clearance between outer and inner rotors
of oil pump;
Service limit
0.20mm
3.4.3.3. Take out the shaft and pin from the oil pump;
Use knife straight edge and feeler gauge to measure
axial clearance between rotor and casing of the oil
pump.
Service limit
0.15mm
3.4.4. Oil pump installation