KYMCO MXU 400 User manual

FOREWORD
This KYMCO Service Manual contains service, maintenance, and troubleshoo tin g information for th e 2008
KYMCO MXU400 ATV. The compl ete manual is des i gned to aid service personnel in service-oriented
applicat ions.
This manual is divided into sections. Each section covers a specific ATV component or system and,
in addition to the standard service procedures, includes disassembling, inspecting, and assembling
instructions. When using this manual as a guide, the technician should use discretion as to how
much disassembly is needed to correct any given condition.
The service technician should become familiar with the operation and construction of each
component or system KYMCO. This manual will assist the service technician in becoming more
aware of and efficient with servicing procedures. Such efficiency not only helps build consumer
confidence but also saves time and labor.
All KYMCO ATV publications and decals display the words Warning, Caution, Note, and At This
Point to emphasize important information.
The symbol identifies personal safety-related information.
Be sure to follow the directive because it deals with the possibility of severe personal injury or even
death. The symbol identifies unsafe practices which may result in ATV-related
damage. Follow the directive because it deals with the possibility of damaging part or parts of the
ATV. The symbol NOTE: identifies supplementary information worthy of particular attention. The
symbol ◎AT THIS POINT directs the tech- nician to certain and specific procedures to promote
efficiency and to improve clarity.
At the time of publication, all information, photographs, and illustrations were technically correct.
Some photographs used in this manual are used for clarity purposes only and are not designed to
depict actual conditions. Because KYMCO Inc. constantly refines and improves its products, no
retroactive obligation is incurred.
All materials and specifications are subject to change without notice. Keep this manual accessible
in the shop area for reference.
Overseas Service D e pa r tm e nt
KYMCO
Inc.
© 2008 KYMCO Inc. March 2008
®™ Trademarks of KYMCO Inc., Taiwan

TABLE OF CONTENTS
Section
1. Genera l Info rm ation / Specificatio ns
1
2. Periodic Main tenanc e
2
3. Engine/Transmission
3
4. Fuel/Lubrication/Cooling
4
5. Electrical System
5
6. Drive System
6
7. Suspension
7
8. Steering/Frame
8
9. Controls/Indicators
9

1-1
1
1
SECTION 1 - GENERAL
INFORM
A
T
ION/ SPECIFIC
A
TIONS
General Specifications ............................................ 1-2
Torque
Specifications .............................................. 1-2
Torque
Conversions (ft-lb/N-m) ............................... 1-3
Tightening
Torque (General Bolts) .......................... 1-3
Break-In
Procedure ................................................. 1-4
Gasoline
- Oil - Lubricant ........................................ 1-4
Genuine
Parts ......................................................... 1-5
Preparation
For Storage .......................................... 1-5
Preparation
After Storage........................................ 1-5
TABLE OF
CONTENTS

1-2
EXHAUST COMPONENTS
Torque
Part Part Bolted To ft-lb N-
m
Exhaust Pipe Engine 20 27
Spark Arrester Muffler 48
in.-lb 5.5
ELECTRICAL COMPONENTS
Coil Frame 12 16
Starter Motor Positive Cable Star t er Motor 8 11
STEERING COMPONENTS
Steering Post Bearing
Housing Frame 20 27
Handlebar Cap Steering Post 20 27
Lower Steering Post Bearing
Cap
Screw Steering
Post 40 54
Tie Rod End** Steering Post Arm 30 41
BRAKE COMPONENTS
Brake Disc* Hub 15 20
Brake Hose Caliper 20 27
Brake Hose Master Cylinder 20 27
Brake Hose Auxiliary
Brake
Cylinder 20 27
Master Cylinder (Rear) Frame 8 11
Master Cylinder Clamp
Screws
(Front) Master
Cylinder 5.5 8
Hydraulic Caliper Knuckle 20 27
CHASSIS COMPONENTS
Foo t rest Frame (8 mm) 20 27
Bumper Frame (10 mm) 35 47
SUSPENSION COMPONENTS (Front)
A-Arm Frame 35 47
Knuckle Ball Join t 35 47
Shock Absorber Frame 35 47
Shock Absorber Upper A-Arm 35 47
Knuckle A-Arm 35 47
SUSPENSION COMPONENTS (Rear)
Shock Absorber (Upper) Frame 35 47
Shock Absorber (Lower) Lower A-Arm 35 47
A-Arm Frame 35 47
Knuckle A-Arm 35 47
General S p ec ificatio ns*
CHASSIS
Brake Type Hydraulic
w/Brake Lever Lock
and
Auxiliary Brake
Tire Size Front - 24 x 8-12
Rear
- 24 x 10-12
Tire I nflation Pressure 0.28 kg/cm² (4 psi)
MISCELLANY
Gas Tank Capacity (rated) 15.1 L (4.0 U . S . gal.)
Rear Drive Capacity 250 ml (8.5 fl oz)**
Front Differential Capacity 275 ml (9.3 fl oz)***
Engine Oil Capacity 3.3 L (3.5 U . S . qt) - Overhaul
2.8
L (3.0 U . S . qt) - Change
Gasoline (recommended) 87 Octane Regular Unleaded
Engine Oil (recommended) KYMCO
Synthetic
Differential/Rear Drive Lubricant SAE Approved 80W-90 Hypoid
Drive Belt Width (minimum) 28.5 mm (1.12 in.)
Brake Fluid DOT 4
Taillight/Brakeligh t 12V/5W/21W
Headlight 12V/35W (4)
Specifications subject to change without notice.
**
One inch below plug threads.
***
At the plug threads.

1-3
1
* w/Blue Loctite #243
** w/Red Loctite #271
*** w/Green Loctite #609
Torque Conversions
(ft-lb/N-m)
Tightening Torque
(General Bolts)
ENGINE/TRANSMISSION
Part Part Bolted To Torque
ft-lb N-m
Clutch Shoe** Crankshaft 147 199
Clutch Cover/Housing Assembly Crankcase 8 11
Left-Side Cover Crankcase 8 11
Crankcase Half (6 mm) Crankcase Half 10 13.5
Crankcase Half (8 mm) Crankcase Half 21 28
Cylinder Head (Cap Screw) Crankcase 28 38
Cylinder Head (6 mm) Cylinder 8 11
Cylinder Head (8 mm) Cylinder 20 27
Cylinder Head Cover Cylinder Head 8 11
Crankshaft Balancer Drive
Gear** Crankshaft 63 86
Driven Pulley Nut** Driveshaft 147 199
Ground Cable Engine 8 11
Output Shaft Flange Nut Output Shaft 74 101
Magneto Rotor Nut Crankshaft 107 146
Cam Sprocket** Camshaft 11 15
V-Belt Cover Crankcase 8 11
Spark Plug Engine 8 11
Valve Adjuster Jam Nut Valve Adjuster 7 9.5
Oil Fitting Engine 8 11
Oil Pump* Crankcase 8 11
Movable Drive Face Nut** Clutch Shaft 147 199
Oil Cooler Hose Clamps Engine/Oil Cooler 30 in.-lb 3.4
DRIVE TRAIN COMPONENTS
Engine Mounting Through-Bolt Frame 38 52
Front Differential* Frame/Differential
Bracket 38 52
Output Flange Rear Flange
Output Joint 20 27
Input Shaft Housing Differential Housing 23 31
Differential Housing Cover*** Differential Housing 23 31
Drive Bevel Gear Nut** Shaft 59 80
Driven Bevel Gear Nut** Driven Shaft 59 80
Hub Nut Shaft/Axle (max) 200 270
Oil Drain Plug Front Differential/
Rear Drive 45 in.-lb 5
Oil Fill Plug Front Differential/
Rear Drive 16 22
Oil Drain Plug Engine 20 27
Wheel Hub 40 54
Rear Drive Gear Case Frame 38 52
Engine Output Flange Rear Gear Case
Input Flange 20 27
ft-lb N-m ft-lb N-m ft-lb N-m ft-lb N-m
11.4 26 35.4 51 69.4 76 103.4
22.7 27 36.7 52 70.7 77 104.7
34.1 28 38.1 53 72.1 78 106.1
45.4 29 39.4 54 73.4 79 107.4
56.8 30 40.8 55 74.8 80 108.8
68.2 31 42.2 56 76.2 81 110.2
79.5 32 43.5 57 77.5 82 111.5
810.9 33 44.9 58 78.9 83 112.9
912.2 34 46.2 59 80.2 84 114.2
10 13.6 35 47.6 60 81.6 85 115.6
11 15 36 49 61 83 86 117
12 16.3 37 50.3 62 84.3 87 118.3
13 17.7 38 51.7 63 85.7 88 119.7
14 19 39 53 64 87 89 121
15 20.4 40 54.4 65 88.4 90 122.4
16 21.8 41 55.8 66 89.8 91 123.8
17 23.1 42 57.1 67 91.1 92 125.1
18 24.5 43 58.5 68 92.5 93 126.5
19 25.8 44 59.8 69 93.8 94 127.8
20 27.2 45 61.2 70 95.2 95 129.2
21 28.6 46 62.6 71 96.6 96 130.6
22 29.9 47 63.9 72 97.9 97 131.9
23 31.3 48 65.3 73 99.3 98 133.3
24 32.6 49 66.6 74 100.6 99 134.6
25 34 50 68 75 102 100 136
Type of Bolt ThreadDiameter
A (mm)
Tightening
Torque
(Conventional or 4 Marked Bolt) 5 12-36 in.-lb
6 36-60 in.-lb
8 7-11 ft-lb
10 16-25 ft-lb
(7 Marked Bolt) 5 24-48 in.-lb
6 6-8 ft-lb
8 13-20 ft-lb
10 29-43 ft-lb

1-4
CAUTION
CAUTION
Break-In Procedure
A new ATV and an overhauled ATV eng i ne
requ
ire a “break-in ” period. Th e first 10 hours (or
200
miles) are most critical to the life of this ATV.
Proper
operation during this break-in period will
help assure maximum life and performance from
the
ATV.
During the first 10 hours (or 200 miles) of
operation, always use less than 1/2 throttle.
Varying the engine RPM during the break-in
period allows the components to “load” (aiding
the mating process) and then “unload” (allowing
components to cool). Although it is essential to
place some stress on the engine components
during break-in, care should be taken not to
overload the engine too often. Do not pull a
trailer or carry heavy loads during the 10-hour
break-in period.
When
the e ngine starts, al low it to warm up
properly. Idle
t h e engine several mi nutes until
the
engine has reached norma l op e rating
te mperature. Do not idle the engine for
excessively
long periods of time.
During the break-in period, a maximum of 1/2
throttle is
recommended; however, brief full-
throttle
acceleratio ns and v ariati ons in driving
speeds
contribute to good engin e bre a k-in.
After
the completion of the break-in period, the
engine
oil and oil filter should be changed. Other
maintenance after
break-in should include
check
i ng of all pre- scribed a djustments and
tightening
of all fasten e rs.
Gasoline - Oil -
Lubricant
RE COMMENDED GASOLINE
The recommended gaso line to use is 87 minimum
octane
regu lar unleaded. In many a reas,
oxyg
e n ate s (either ethanol or MTBE) are added to
the
gasoline. Oxygenated gasolines conta i n i ng up
to
10% ethano l, 5% methane, or 5% MTBE a r e
acc
eptable gasolines.
When
using ethanol blended gasoline, it is not
necessary
to add a gasoline antifreeze since
ethanol
will prevent the accumulation of moisture
in
the fuel system.
RE COMME N DED ENG I NE/
TRANSMISSION OIL
Any oil used in place of the recommended oil could
cause
serious engine damage . Do not use oils which
contain
graphite or molybdenum additives. These oils
can
adversely affect c l utch operat ion. Also, not
recommended
are racing, vegetable , non-detergent,
and
castor-based oils .
The recommended oil that using of any API
certified
SM 5W-50 oil is ac ceptable.
RE COMME N DED FRONT
DIFFER ENTIAL/RE A R DRIVE
LU BRICANT
Th e recommended lubricant is KYMCO Gear
Lube or
an equiv a len t gear lub e which is SAE
approved 80W-90
hypoid. This lubrican t meets
all of the lubrication requirements of the KYMCO
ATV
front differen tials and rear drives.
Any lubricant used in place of the recommended
lubricant
could cause serious front differential/rear drive
damage
.

FI LLI NG GAS TANK
1.Clean the seat cushion (cover and base) with
a
damp cloth and allow it to dry.
2.Clean
the ATV thoroughly by washing dirt, oil,
grass,
and other foreign matter from the entire
ATV. Allow the ATV to dry thoroughly. DO
NOT
ge t water into any part of the engine or air
intake.
3.Either
drain the gas tank or add Fuel Stabilizer
to
the gas in the gas tank. Remove the air filter
housing
cover and air filter. Start the engine
and
allow it to idle; then using KYMCO Engine
Storage
Preserver, rapidly inject the preserver
into
the air filter opening for a period of 10 to
20
seconds; then stop the engine. Install the
air
filter and housing cove r.
If the interio
r
of the ai
r
filte
r
housing is dir
t
y , c l ean the
area
before starting the engine .
A
T
V
0049B
Since gasoline expands a s it s tempera t ure rises,
the
gas tank mus t be f illed to it s rated capacity
only
. Expansion room mus t be m a in t ained in the
tank
parti c ularly if the t ank is fill ed wi t h cold
gasoline
and t hen moved to a warm area .
4.Drain th e carburetor float chamber .
5.Plug the exhaust outlet on the muffler with a
clean
cloth.
6.Apply light oil to the upper steering post
bushing and plungers of the shock absorbers.
7.Tighten all
nuts, bolts, cap screws , and
screws. Make sure rivets holding components
together
are tight. Replace all loose rivets .
Care must be taken that all calibrated nuts,
cap
screws, and bolts are tightened to
specifications.
8.Turn the gas tank valve to the OFF position.
9.Disconnect
the battery cables; then remove
the
battery, clean the battery posts and
cables
, and store in a clean, dry area .
10.S t ore the ATV indoors in a level position.
Do not over f low gasoline when filling the gas tank . A
f ire hazard could materialize . A l ways allow the engine
to cool
before filling the gas tank.
Tighten the gas tank cap securely afte
r
filling the
tank.
Do not over-fill the gas tank.
Genuine Parts
When replacement of parts is necessary, use
only
genuine KYMCO ATV parts. They are
precision-made
to ensure high quality and
correct
fit. Refer to the appropriate Illustrated
Parts
Manual for the correct part number,
quantity,
and description.
Avoid stor in g outside in direct sunlight and avoid
using a
plastic cover as moisture will collect on the
ATV causing
rusting.
Preparation
A
fte
r
Storage
Taking the ATV out of storage and correctly
preparing
it will assure many miles and hours of
trouble-free
riding. KYMCO recommends the
following
procedure to prepare the ATV.
1. Clean th e ATV t horoughly .
.
2. Clean the engine . Remove the cloth from the
muffler.
Preparation Fo
r
Storage
Prio
r
to storing the
A
TV , it mus t be p
r
ope
r
ly se
r
viced to
prevent
rus t ing and component deterioratio n.
KYMCO recommends the f ollowing procedure to
prepare
the ATV for storage.
1-5
CAUTION
CAUTION
WARNING
WARNING
CAUTION
WARNING
Always fill the gas tank in a well-ventilated area
.
Never add fuel to the ATV gas tank near any ope
n
flames or with the engine runn ing. DO NO
T
SMOKE while filling the gas tank.
1

1-6
CAUTION
The ignition switch must be in the OFF position
prior to installing the battery or damage may occur
to the ignition system.
CAUTION
Connect the positive battery cable first, then the
negative
.
3. Che c k all control cables for signs of wear or
fraying.
R e pla ce if necessary.
4.
Change th e e ngin e/tr ansmission oil and fi lter .
5.
Charg e th e ba tte ry; then install. Connect
the
bat te ry ca b l es.
6.Check
the e n tire brake sys t ems (fluid level,
pads, etc.), all c ontrols, lights, and
headlight aim; adjust or replac e as
necessary.
7.T
i ghten all nuts, bolts, cap screws, and
screws making sure all calibrate d nuts, cap
screws,
and bolts are tightened to
specifications.
8.Check tire pressure, Inflate to recommended
pressure as necessary.
9.Make sure the steering moves freely and
does not bind.
10.Check the spark plug. Clean or replace as
necessary.