Yamaha YFM 400 FWA P User manual

YFM400FWA(P)
5GH3-AE2
SUPPLEMENTARY
SERVICE MANUAL
2002

FOREWORD
This Supplementary Service Manual has been prepared to introduce new service and new data for
the YFM400FWA(P) 2002. For complete information on service procedures, it is necessary to use
this Supplementary Service Manual together with the following manual.
YFM400FWA(M) 2000 SERVICE MANUAL: 5GH3-AE1
YFM400FWA(P) 2002
SUPPLEMENTARY
SERVICE MANUAL
 2001 by Yamaha Motor Co., Ltd.
First Edition, June 2001
All rights reserved.
Any reproduction or unauthorized use
without the written permission of
Yamaha Motor Co., Ltd.
is expressly prohibited.

EB001000
NOTICE
This manual was produced by the Yamaha Motor Company primarily for use by Yamaha dealers
and their qualified mechanics. It is not possible to include all the knowledge of a mechanic in one
manual, so it is assumed that anyone who uses this book to perform maintenance and repairs on
Yamaha machine has a basic understanding of the mechanical ideas and the procedures of
machine repair. Repairs attempted by anyone without this knowledge are likely to render the
machine unsafe and unfit for use.
Yamaha Motor Company, Ltd. is continually striving to improve all its models. Modifications and sig-
nificant changes in specifications or procedures will be forwarded to all authorized Yamaha dealers
and will appear in future editions of this manual where applicable.
N
OTE:
Designs and specifications are subject to change without notice.
IMPORTANT INFORMATION
Particularly important information is distinguished in this manual by the following notations.
The Safety Alert Symbol means ATTENTION! BECOME ALERT! YOUR
SAFETY IS INVOLVED!
Failure to follow WARNING instructions could result in severe injury or death
to the machine operator, a bystander or a person inspecting or repairing the
machine.
A CAUTION indicates special precautions that must be taken to avoid dam-
age to the machine.
A NOTE provides key information to make procedures easier or clearer.
WARNING
CAUTION:
N
O
TE:

EB002000
HOW TO USE THIS MANUAL
MANUAL ORGANIZATION
This manual consists of chapters for the main categories of subjects. (See “Illustrated symbols”)
1st title 1: This is the title of the chapter with its symbol in the upper right corner of each page.
2nd title 2: This title indicates the section of the chapter and only appears on the first page of each
section. It is located in the upper left corner of the page.
3rd title 3: This title indicates a sub-section that is followed by step-by-step procedures accompa-
nied by corresponding illustrations.
EXPLODED DIAGRAMS
To help identify parts and clarify procedure steps, there are exploded diagrams at the start of each
removal and disassembly section.
1. An easy-to-see exploded diagram 4is provided for removal and disassembly jobs.
2. Numbers 5are given in the order of the jobs in the exploded diagram. A number that is enclosed
by a circle indicates a disassembly step.
3. An explanation of jobs and notes is presented in an easy-to-read way by the use of symbol marks
6. The meanings of the symbol marks are given on the next page.
4. A job instruction chart 7accompanies the exploded diagram, providing the order of jobs, names
of parts, notes in jobs, etc.
5. For jobs requiring more information, the step-by-step format supplements 8are given in addition
to the exploded diagram and the job instruction chart.

EB003000
ILLUSTRATED SYMBOLS
Illustrated symbols 1to 9are printed on the
top right of each page and indicate the subject
of each chapter.
1General information
2Specifications
3Periodic checks and adjustments
4Engine
5Carburetion
6Drive train
7Chassis
8Electrical
9Troubleshooting
Illustrated symbols 0to Fare used to identify
the specifications appearing in the text.
0Filling fluid
ALubricant
BSpecial tool
CTorque
DWear limit, clearance
EEngine speed
FΩ, V, A
Illustrated symbols Gto Min the exploded
diagrams indicate the types of lubricants and
lubrication points.
GApply engine oil
HApply gear oil
IApply molybdenum disulfide oil
JApply wheel bearing grease
KApply lightweight lithium soap base grease
LApply molybdenum disulfide grease
MApply silicon grease
Illustrated symbols Nto Oin the exploded
diagrams indicate where to apply a locking
agent Nand when to install a new part O.
NApply the locking agent (LOCTITE)
OReplace
12
34
56
78
90
AB
CD
EF
GHI
J
NO
GEN
INFO SPEC
CHK
ADJ ENG
CARB
DRIV
CHAS
–+
ELEC
TRBL
SHTG
T
R
.
.
EGM
BLS MS
KLM
LT New

CONTENTS
SPECIFICATIONS ............................................................................................1
GENERAL SPECIFICATIONS ..................................................................1
MAINTENANCE SPECIFICATIONS .........................................................2
ENGINE ................................................................................................2
ELECTRICAL ........................................................................................4
CABLE ROUTING .....................................................................................5
PERIODIC CHECKS AND ADJUSTMENTS ..................................................15
INTRODUCTION .....................................................................................15
PERIODIC MAINTENANCE/LUBRICATION INTERVALS ......................15
CHASSIS .................................................................................................17
ADJUSTING THE REAR BRAKE LIGHT SWITCH .............................17
ENGINE ..........................................................................................................18
CYLINDER HEAD ...................................................................................18
CYLINDER HEAD INSTALLATION ....................................................18
RECOIL STARTER AND CDI MAGNETO ..............................................21
TRANSMISSION .....................................................................................23
ELECTRICAL .................................................................................................25
ELECTRIC STARTING SYSTEM ............................................................25
CIRCUIT DIAGRAM ............................................................................25
TROUBLESHOOTING ........................................................................26
SIGNAL SYSTEM ...................................................................................29
CIRCUIT DIAGRAM ............................................................................29
CHECKING THE SIGNAL SYSTEM ...................................................31
YFM400FWA(P) 2002 WIRING DIAGRAM

–1 –
SPEC
GENERAL SPECIFICATIONS
SPECIFICATIONS
GENERAL SPECIFICATIONS
Item Standard
Model code: 5GHL: (CDN)
5GHM: (Europe)
5GHN: (Oceania)
Engine:
Engine type Liquid-cooled 4-stroke, SOHC
Cylinder arrangement Forward-inclined single cylinder
Displacement 401 cm³
Bore ×stroke 84.5 ×71.5 mm (3.33 ×2.81 in)
Compression ratio 10.5 : 1
Standard compression pressure (at sea level) 1,400 kPa (14.0 kg/cm², 203 psi) at 750 r/min
Starting system Electric and recoil starter
Lubrication system: Wet sump
Tire pressure (cold tire):
Maximum load* 210 kg (463 Ib)
Off-road riding front 22 ~ 28 kPa (0.22 ~ 0.28 kg/cm², 3.2 ~ 4.1 psi)
rear 22 ~ 28 kPa (0.22 ~ 0.28 kg/cm², 3.2 ~ 4.1 psi)
*Load in total weight of rider accessories
Electrical:
Ignition system DC. C.D.I.
Generator system A.C. magneto
Battery type YTX20L-BS
Battery capacity 12 V 18 AH
Bulb wattage ×quantity:
Headlight 12 V 30 W/30 W ×2
Tail/brake light 12 V 5 W/21 W ×1
Indicator lights
Neutral 12 V 1.7 W ×1
Reverse 12 V 1.7 W ×1
Coolant temperature 12 V 1.7 W ×1
Four-wheel drive 12 V 1.7 W ×1
Park 12 V 1.7 W ×1

–2 –
SPEC
MAINTENANCE SPECIFICATIONS
MAINTENANCE SPECIFICATIONS
ENGINE
Item Standard Limit
Cylinder:
Bore size 84.500 ~ 84.510 mm
(3.3268 ~ 3.3272 in)
84.600 mm
(3.3307 in)
Taper limit ---- 0.05 mm
(0.0016 in)
Out of round limit ---- 0.01 mm
(0.0004 in)
Measuring point 40 mm (1.57 in) ----
Cam chain:
Cam chain type/No. of links DID SCR-0409 SDH/116 ----
Cam chain adjustment method Automatic ----
Rocker arm/rocker arm shaft:
Bearing inside diameter 12.000 ~ 12.018 mm
(0.4724 ~ 0.4731 in)
12.078 mm
(0.4755 in)
Shaft outside diameter 11.981 ~ 11.991 mm
(0.4717 ~ 0.4721 in)
11.951 mm
(0.4705 in)
Arm-to-shaft clearance 0.009 ~ 0.037 mm
(0.0004 ~ 0.0015 in)
0.08 mm
(0.0031 in)
Piston:
Piston to cylinder clearance 0.040 ~ 0.065 mm
(0.0016 ~ 0.0026 in)
0.15 mm
(0.0059 in)
Piston size “D”84.445 ~ 84.460 mm
(3.3246 ~ 3.3252 in)
----
Measuring point “H”5 mm (0.20 in) ----
Piston off-set 0.5 mm (0.0200 in) ----
Off-set direction Intake side ----
Piston pin bore inside diameter 20.004 ~ 20.015 mm
(0.7876 ~ 0.7880 in)
20.045 mm
(0.7892 in)
Piston pin outside diameter 19.993 ~ 20.000 mm
(0.7871 ~ 0.7874 in)
19.973 mm
(0.7863 in)
*
H
D

–3 –
SPEC
MAINTENANCE SPECIFICATIONS
Automatic centrifugal clutch:
Clutch shoe thickness 1.5 mm (0.06 in) 1.0 mm
(0.04 in)
Clutch-in revolution 1,960 ~ 2,240 r/min ----
Clutch-stall revolution 3,300 ~ 3,900 r/min ----
Carburetor:
I.D.mark 5GH9 11 ----
Main jet (M.J) #130 ----
Main air jet (M.A.J) #50 ----
Jet needle (J.N) 5EP3-55-3 ----
Needle jet (N.J) P-0M ----
Pilot air jet (P.A.J.1) #80 ----
Pilot air jet (P.A.J.2) 1.3 ----
Pilot outlet (P.O) 0.95 ----
Pilot jet (P.J) #17.5 ----
Bypass1 (B.P.1) 0.8 ----
Bypass2 (B.P.2) 0.8 ----
Bypass3 (B.P.3) 0.8 ----
Valve seat size (V.S) 2.0 ----
Starter jet (G.S.1) #70 ----
Starter jet (G.S.2) 0.9 ----
Throttle valve size (Th.V) #90 ----
Float height (F.H) 13 mm (0.51 in) ----
Fuel level (F.L) 3 ~ 4 mm (0.12 ~ 0.16 in) ----
Engine idle speed 1,450 ~ 1,550 r/min ----
Intake vacuum 32 kPa (240 mmHg, 9.45 inHg) ----
Oil filter type: Foam ----
Oil pump:
Oil pump type Trochoid ----
Tip clearance “A”or “B”0.15 mm (0.006 in) 0.2 mm
(0.008 in)
Side clearance 0.04 ~ 0.09 mm
(0.0016 ~ 0.0035 in)
----
Bypass valve setting pressure 78 ~ 118 kPa
(0.78 ~ 1.18 kg/cm², 11.3 ~
17.11 psi)
----
Oil pressure (hot) 7 kPa (0.07 kg/cm², 1.02 psi) at
1,500 r/min
----
Pressure check location Cylinder head ----
Shaft drive:
Middle gear backlash 0.1 ~ 0.3 mm
(0.0039 ~ 0.0118 in)
----
Final gear backlash 0.1 ~ 0.2 mm
(0.0039 ~ 0.0079 in)
----
Differential gear backlash 0.05 ~ 0.25 mm
(0.002 ~ 0.0098 in)
----
Item Standard Limit

–4 –
SPEC
MAINTENANCE SPECIFICATIONS
ELECTRICAL
Item Standard Limit
C.D.I.:
Magneto model/manufacturer F4T46471/MITSUBISHI ----
Pickup coil resistance/color 459 ~ 561 Ωat 20 °C (68 °F)/
/White/Red-White/Green
----
Rotor rotation direction sensing coil resis-
tance/color
0.104 ~ 0.127 Ωat 20 °C (68 °F)/
Red-White/Blue
----
C.D.I. unit model/manufacturer F8T38672/MITSUBISHI ----
Ignition coil:
Model/manufacturer 2JN/MORIYAMA ----
Minimum spark gap 6 mm (0.24 in) ----
Primary winding resistance 0.18 ~ 0.28 Ωat 20 °C (68 °F) ----
Secondary winding resistance 6.32 ~ 9.48 kΩat 20 °C (68 °F) ----
Charging system:
Type A.C. magneto generator ----
Model/manufacturer F4T464/MITSUBISHI ----
Nominal output 14 V 210 W 5,000 r/min ----
Charging coil resistance/color 0.70 ~ 0.86 Ωat 20 °C (68 °F)/
White-White
----
Rectifier/regulator:
Type Semi conductor-short circuit ----
Model/manufacturer SH640E-11/SHINDENGEN ----
No load voltage (DC) 14.1 ~ 14.9 V ----
Capacity 14 A ----
Withstand voltage 200 V ----
Battery:
Specific gravity 1,320 ----

–5 –
SPEC
CABLE ROUTING
1Rear brake switch
2Rear brake cable
3Front brake hose
4On command four-wheel drive switch
5Throttle cable
6Horn switch
123
4
5
6
CABLE ROUTING

–6 –
SPEC
1On command four-wheel drive switch lead
2Front brake hose
3Throttle cable
4Rear brake cable
5Rear brake switch lead
6Handlebar switch
7Starter cable
8Coolant reservoir breather hose
9Sub-wire harness 1 (to fan motor coupler)
0Sub-wire harness 1 (to gear motor and four-
wheel drive switch)
ADifferential gear case breather hose
BFan motor breather hose
CFront brake light switch lead
C
1
23456
7
8
9
0
A
B
CABLE ROUTING

–7 –
SPEC
1Headlight coupler
2Circuit breaker
3Terminal
4Terminal coupler
5Engine temperature warning light
6Four-wheel drive indicator light
7Neutral indicator light
8Reverse indicator light
9Parking indicator light
0Coolant reservoir breather hose
ADifferential gear case breather hose
BIndicator light coupler
CMain switch coupler
DIgnition coil lead
ÈConnect the headlight lead of the circuit breaker
to the headlight on the right side.
3
45678
9
0
A
1
1
2
È
B
4B
C
D
A
A
CABLE ROUTING

–8 –
SPEC
1Thermo switch
2Fuel tank breather hose
3Carburetor drain hose
4Speedometer cable
5Coolant reservoir breather hose
6Coolant reservoir hose
7Sub-wire harness 1
ÈTo hole on the front fender.
ÉInsert the fuel tank into the hole in the handlebar
cover.
Ê10 mm (0.4 in)
E
E
E
E
D
D
D
D
C
C
B
77
6
5
1
2
5
6
3
4
È
É
A
A
B
C-C D-D E-E
Ê
CABLE ROUTING

–9 –
SPEC
1Neutral switch lead
2Starter motor lead
3Negative battery lead
4Water pump breather hose
5Speed sensor
6Carburetor drain hose
7Wire harness
8Sub-wire harness 2
9Ground lead
0AC magneto lead
AFinal drive gear case breather hose
BSpeed sensor
CRectifier/regulator
A
A
B
7
BA
0
9
8
A
C
654
3
2
1
ÈÉ
Ê
AB
CABLE ROUTING

–10 –
SPEC
ÈFasten the AC magneto lead and starter motor lead with a plastic band.
ÉTo hole on the rear fender.
Ê120 mm (4.72 in)
A
A
B
7
BA
0
9
8
A
C
654
3
2
1
ÈÉ
Ê
AB
CABLE ROUTING

–11 –
SPEC
1Spark plug lead
2Rear brake cable
3Select lever control cable
4Rear brake reservoir hose
5Rear brake light switch lead
ÈFasten the radiator inlet hose and fan motor
breather hose with a plastic band.
ÉPass the rear brake cable through the cable
guide.
ÊPass the rear brake reservoir hose, select lever
control cable, and rear brake light switch lead
through the cable guide.
A-A
A
A
1
23
4
5
4
É
Ê
È
CABLE ROUTING

–12 –
SPEC
1Fan motor breather hose
2Cylinder head breather hose
3Air filter case breather hose
4Rear brake hose
5Final drive gear case breather hose
A-A
3
5
4
4
3
12
B
B
A
A
A
A
4
CABLE ROUTING