Yamaha 2002 YFA1 Manual

YFA1(P)
SUPPLEMENTARY
SERVICE MANUAL
3FA-AE1
2002

FOREWORD
This Supplementary Service Manual has been prepared to introduce new service and new data for
the YFA1(P) 2002. For complete information on service procedures, it is necessary to use this Sup-
plementary Service Manual together with the following manual.
YFA1W SERVICE MANUAL: 3FA-ME1
YFA1(P) 2002
SUPPLEMENTARY
SERVICE MANUAL
 2001 by Yamaha Motor Co., Ltd.
First Edition, May 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:

HOW TO USE THIS MANUAL
CONSTRUCTION OF THIS MANUAL
This manual consists of chapters for the main categories of subjects. (See “Illustrated symbols”)
1st title 1: This is a chapter with its symbol on the upper right of each page.
2nd title 2: This title appears on the upper of each page on the left of the chapter sym-
bol. (For the chapter “Periodic inspection and adjustment” the 3rd title
appears.)
3rd title 3: This is a final title.
MANUAL FORMAT
All of the procedures in this manual are organized in a sequential, step-by-step format. The informa-
tion has been compiled to provide the mechanic with an easy to read, handy reference that contains
comprehensive explanations of all disassembly, repair, assembly, and inspections.
A set of particularly important procedure 4is placed between a line of asterisks “*” with each proce-
dure preceded by “●”.
IMPORTANT FEATURES
●Data and a special tool are framed in a box preceded by a relevant symbol 5.
●An encircled numeral 6indicates a part name, and an encircled alphabetical letter data or an
alignment mark 7, the others being indicated by an alphabetical letter in a box 8.
●A condition of a faulty component will precede an arrow symbol 9and the course of action will fol-
low it.
EXPLODED DIAGRAM
Each chapter provides exploded diagrams before each disassembly section for ease in identifying
correct disassembly and assembly procedures.

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
GENERAL INFORMATION ..............................................................................1
MACHINE IDENTIFICATION ....................................................................1
MODEL LABEL .....................................................................................1
SPECIFICATIONS ............................................................................................2
GENERAL SPECIFICATIONS ..................................................................2
MAINTENANCE SPECIFICATIONS .........................................................3
ENGINE ................................................................................................3
CHASSIS ..............................................................................................5
ELECTRICAL ........................................................................................6
CABLE ROUTING .....................................................................................8
PERIODIC CHECKS AND ADJUSTMENTS ..................................................14
INTRODUCTION .....................................................................................14
PERIODIC MAINTENANCE/LUBRICATION INTERVALS ......................14
CHASSIS .................................................................................................15
ADJUSTING THE FRONT BRAKE .....................................................15
CHASSIS ........................................................................................................16
STEERING SYSTEM ..............................................................................16
ELECTRICAL .................................................................................................17
CHECKING THE SWITCH ......................................................................17
CHECKING THE SWITCH ..................................................................17
CHECKING A SWITCH SHOWN IN THE MANUAL ...........................17
SIGNAL SYSTEM ...................................................................................18
CIRCUIT DIAGRAM ............................................................................18
CHECKING THE SIGNAL SYSTEM ...................................................19
YFA1(P) 2002 WIRING DIAGRAM

–1 –
GEN
INFO
MACHINE IDENTIFICATION
GENERAL INFORMATION
MACHINE IDENTIFICATION
MODEL LABEL
The model label 1is affixed to the frame. This
information will be needed to order spare
parts.

–2 –
SPEC
GENERAL SPECIFICATIONS
SPECIFICATIONS
GENERAL SPECIFICATIONS
Model YFA1 (P) 2002
Model code number 3FAY (CDN, Europe and Oceania)
Engine:
Engine type Air-cooled 4-stroke, SOHC
Cylinder arrangement Forward-inclined single cylinder
Displacement 124 cm3
Bore ×stroke 49 ×66 mm (1.93 ×2.60 in)
Compression ratio 9.0 : 1
Compression pressure 850 kPa (8.5 kg/cm2, 121 psi) at 570 r/min
Starting system Electric starter
Transmission:
Primary reduction system Helical gear/spur gear
Primary reduction ratio 43/14 ×40/17 (7.226)
Secondary reduction system Chain drive
Secondary reduction ratio 32/12 (2.666)
Clutch type Dry, centrifugal automatic
Transmission type Single speed automatic (V-belt)
Operation Centrifugal automatic type
Single speed automatic 2.303 ~ 0.821
Reverse ratio 49/14 ×49/15 ×40/17 (26.902)
Tire:
Type Tubeless
Size
Front AT20 ×7–8
Rear AT22 ×10–8
Manufacturer (type)
Front DUNLOP (KT536A)
Rear DUNLOP (KT537A)
Wear limit 3.0 mm (0.12 in)
Electrical:
Ignition system CDI
Generator system A.C. magneto generator
Battery capacity 12 V 12 AH
Battery type 12N12C-4A-2
Headlight type Bulb type
Headlight bulb type Incandescence
Bulb wattage (quantity)
Headlight 12 V 25 W/25 W (1 pc.)
Tail/brake light 12 V 5 W/21 W (1 pc.)
Neutral indicator light 12 V 3.4 W (1 pc.)
Reverse indicator light 12 V 3.4 W (1 pc.)

–3 –
SPEC
MAINTENANCE SPECIFICATIONS
MAINTENANCE SPECIFICATIONS
ENGINE
Model YFA1 (P) 2002
Cylinder:
Bore size 48.99 ~ 49.03 mm (1.9287 ~ 1.9303 in)
<Wear limit> <49.15 mm (1.935 in)>
Measuring point “*”45 mm (1.77 in)
Camshaft:
Drive method Chain drive (left)
Cam dimensions
Intake “A”26.169 ~ 26.269 mm (1.0303 ~ 1.0342 in)
“B”21.061 ~ 21.161 mm (0.8292 ~ 0.8331 in)
“C”5.159 ~ 5.279 mm (0.2031 ~ 0.2078 in)
Exhaust “A”26.169 ~ 26.269 mm (1.0303 ~ 1.0342 in)
“B”21.061 ~ 21.161 mm (0.8292 ~ 0.8331 in)
“C”5.159 ~ 5.279 mm (0.2031 ~ 0.2078 in)
Camshaft runout limit 0.03 mm (0.0012 in)
Rocker arm/rocker arm shaft:
Inside diameter (rocker arm) 10.000 ~ 10.015 mm (0.3937 ~ 0.3943 in)
Outside diameter (shaft) 9.981 ~ 9.991 mm (0.3930 ~ 0.3933 in)
Arm-to-shaft clearance 0.009 ~ 0.034 mm (0.0004 ~ 0.0013 in)
Valve, valve seat, valve guide:
Valve clearance (cold)
Intake 0.08 ~ 0.12 mm (0.0031 ~ 0.0047 in)
Exhaust 0.10 ~ 0.14 mm (0.0039 ~ 0.0055 in)
Valve dimensions
“A”head diameter
Intake 25.9 ~ 26.1 mm (1.02 ~ 1.03 in)
Exhaust 21.9 ~ 22.1 mm (0.86 ~ 0.87 in)
“B”face width
Intake 1.4 ~ 3.0 mm (0.06 ~ 0.12 in)
Exhaust 1.7 ~ 2.8 mm (0.07 ~ 0.11 in)
“C”seat width
Intake 0.9 ~ 1.1 mm (0.035 ~ 0.043 in)
Exhaust 0.9 ~ 1.1 mm (0.035 ~ 0.043 in)
“D”margin thickness
Intake 0.4 ~ 0.8 mm (0.016 ~ 0.031 in)
Exhaust 0.8 ~ 1.2 mm (0.031 ~ 0.047 in)
Outside diameter (valve stem)
Intake 4.975 ~ 4.990 mm (0.196 in)
Exhaust 4.960 ~ 4.975 mm (0.195 ~ 0.196 in)
C
A
B
A
B
C
D

–4 –
SPEC
MAINTENANCE SPECIFICATIONS
Inside diameter (valve guide)
Intake 5.000 ~ 5.012 mm (0.197 in)
Exhaust 5.000 ~ 5.012 mm (0.197 in)
Stem-to-guide clearance
Intake 0.010 ~ 0.037 mm (0.004 ~ 0.0014 in)
Exhaust 0.025 ~ 0.052 mm (0.0010 ~ 0.0020 in)
Stem runout limit 0.01 mm (0.0004 in)
Valve seat width
Intake 0.9 ~ 1.1 mm (0.035 ~ 0.043 in)
Exhaust 0.9 ~ 1.1 mm (0.035 ~ 0.043 in)
Piston:
Piston size “D”48.96 ~ 49.00 mm (1.927 ~ 1.929 in)
Measuring point “H”6 mm (0.24 in)
From bottom of the piston.
Piston-to-cylinder clearance 0.020 ~ 0.040 mm (0.0008 ~ 0.0016 in)
<Wear limit> <0.15 mm (0.006 in)>
Over size 2nd 49.5 mm (1.95 in)
4th 50.0 mm (1.97 in)
Piston off-set 0.5 mm (0.02 in)
Piston off-set direction Intake side
Inside diameter (piston pin bore) 13.002 ~ 13.013 mm (0.5119 ~ 0.5123 in)
Outside diameter (piston pin) 12.996 ~ 13.000 mm (0.5117 ~ 0.5118 in)
Piston pin-to-piston clearance 0.002 ~ 0.017 mm (0.0001 ~ 0.0006 in)
<Limit> <0.07 mm (0.003 in)>
Piston ring:
Ty p e
Top ring Barrel
2nd ring Taper
Dimension (B ×T)
Top ring 1.0 ×2.0 mm (0.039 ×0.079 in)
Second ring 1.0 ×2.0 mm (0.039 ×0.079 in)
Oil ring 2.0 ×2.2 mm (0.079 ×0.087 in)
End gap (installed)
Top ring 0.15 ~ 0.30 mm (0.006 ~ 0.012 in)
Second ring 0.15 ~ 0.30 mm (0.006 ~ 0.012 in)
Oil ring 0.20 ~ 0.80 mm (0.008 ~ 0.031 in)
Model YFA1 (P) 2002
H
D
T
B
B
T
B
T

–5 –
SPEC
MAINTENANCE SPECIFICATIONS
CHASSIS
Side clearance
Top ring 0.03 ~ 0.07 mm (0.0012 ~ 0.0027 in)
Second ring 0.02 ~ 0.06 mm (0.0008 ~ 0.0024 in)
Carburetor:
I.D. mark 3FA02
Main jet (M.J.) #82.5
Main air jet (M.A.J.) ø1.3
Jet needle (J.N.) 4H36-3
Needle jet (N.J.) N-6
Cutaway (C.A.) 2.5
Pilot air jet (P.A.J.) #130
Pilot outlet (P.O.) ø0.7
Pilot jet (P.J.) #12.5
Bypass 1 (B.P.1) 1.1
Pilot screw (P.S.) 2 and 1/2 turns out
Valve seat size (V.S.) 1.8
Starter jet (G.S.) #45
Float height (F.H.) 21.8 mm (0.858 in)
Fuel level (F.L.) 4.0 ~ 6.0 mm (0.16 ~ 0.24 in)
With special tool
Engine idling speed 1,650 ~ 1,750 r/min
Intake vacuum 26.7 kPa (200 mm Hg, 7.88 in Hg)
Model YFA1 (P) 2002
Suspension:
Suspension travel
Front 41 mm (1.614 in)
Rear 60 mm (2.362 in)
Free length (spring)
Front 148 mm (5.827 in)
Rear 205 mm (8.071 in)
Installed length
Rear 180 mm (7.09 in)
Spring rate
Front 29.4 N/mm (3.0 kg/mm, 167.9 lb/in)
Rear 36.3 N/mm (3.7 kg/mm, 207.3 lb/in)
Stroke
Front 0.0 ~ 41 mm (0.0 ~ 1.614 in)
Rear 0.0 ~ 60 mm (0.0 ~ 2.362 in)
Optional spring
Front No
Rear No
Model YFA1 (P) 2002

–6 –
SPEC
MAINTENANCE SPECIFICATIONS
ELECTRICAL
Drive chain:
Type/manufacturer 520V6/DAIDO
Number of links 74 links
Chain slack 30 mm (1.18 in)
10-link length limit 150.1 mm (5.909 in)
Brake lever:
Free play
Front brake 5 ~ 8 mm (0.20 ~ 0.31 in)
At lever pivot.
Rear brake 5 ~ 8 mm (0.20 ~ 0.31 in)
At lever pivot.
Model YFA1 (P) 2002
C.D.I.:
Magneto model/manufacturer F3FA/YAMAHA
Pickup coil resistance 248 ~ 372 Ωat 20 °C (68 °F)
(lead color) (White–Red)
C.D.I. unit model/manufacturer 3FA/YAMAHA
Ignition coil:
Model/manufacturer 2JN/YAMAHA
Minimum spark gap 6.0 mm (0.24 in)
Primary coil resistance 0.18 ~ 0.28 Ωat 20 °C (68 °F)
Secondary coil resistance 6.32 ~ 9.48 kΩat 20 °C (68 °F)
Spark plug cap:
Material Resin
Resistance 10 kΩat 20 °C (68 °F)
Charging system:
Type A.C. magneto generator
Magneto model/manufacturer F3FA/YAMAHA
Charging coil resistance 0.96 ~ 1.44 Ωat 20 °C (68 °F)
(lead color) (Black–White)
Charging current
Day (Minimum) 0.8 A at 3,000 r/min
(Maximum) 2.0 A at 8,000 r/min
Night (Minimum) 0.6 A at 3,000 r/min
(Maximum) 3.5 A at 8,000 r/min
Lighting coil resistance 0.72 ~ 1.08 Ωat 20 °C (68 °F)
(lead color) (Black–Yellow)
Lighting voltage (Minimum) 12.0 V at 3,000 r/min
(Maximum) 14.8 V at 8,000 r/min
Standard output 14 V 125 W at 5,000 r/min
Model YFA1 (P) 2002

–7 –
SPEC
MAINTENANCE SPECIFICATIONS
Rectifier/regulator:
Model/manufacturer EHU–01TR31/MATSUSHITA
Regulator type Semi conductor short circuit type
No load regulated voltage (DC) 14.0 ~ 15.0 V
No load regulated voltage (AC) 13.0 ~ 14.0 V
Rectifier capacity (DC) 8.0 A
Rectifier capacity (AC) 8.0 A
Withstand voltage 200 V
Electric starting system:
Type Constant mesh
Starter motor
Model/manufacturer 3FA1/YAMAHA
Output 0.4 kW
Armature coil resistance 0.019 ~ 0.023 Ωat 20 °C (68 °F)
Overall length (brush) 10.0 mm (0.39 in)
<Limit> <3.5 mm (0.14 in>
Brush spring pressure 552 ~ 828 g
Commutator diameter 22.0 mm (0.87 in)
<Wear limit> <21.0 mm (0.83 in)>
Mica undercut 1.5 mm (0.06 in)
Starter relay
Model/manufacturer MS5D–611/JIDECO
Amperage rating 100 A
Coil resistance 3.87 ~ 4.73 Ωat 20 °C (68 °F)
Starting circuit cut-off relay
Model/manufacturer ACA1211–9/MATSUSHITA
Coil resistance 72 ~ 88 Ωat 20 °C (68 °F)
Diode No
Model YFA1 (P) 2002
16(V)
12(V)
8(V)
4(V)
1(A)
2(A)
3(A)
4(A)
0 246810
VL
Engine speed (×1000 r/min)
Charging current (A)
Lighting voltage (V)
Ich (Day)
Ich (Night)

–8 –
SPEC
CABLE ROUTING
1Throttle cable
2Band
3Breather hose
4Rear brake switch lead
5Rear brake cable
6Front brake cable
7Front brake switch lead
CABLE ROUTING

–9 –
SPEC
1Front brake cable
2Band
3Rear brake cable
4Rear brake switch lead
5CDI unit
6Wire harness
7Main switch
8Front brake switch lead
ÈPass leads in front of the brake cable and con-
nect them inside the headlight body.
ÉPass the inlet and outlet hoses between the
brake cables.
ÊClamp the front brake switch lead, rear brake
switch lead, main switch lead, handlebar switch
lead, and wire sub-leads with a plastic clamp.
ËPass the leads between the throttle cable and
front brake cable.
CABLE ROUTING

–10 –
SPEC
1Throttle cable
2Rectifier/regulator
3Starting motor
4CDI magneto lead
5Clamp
6Ignition coil
ÈFasten the wire harness, starting motor lead and
transmission case breather hose to the frame with
a plastic band.
CABLE ROUTING

–11 –
SPEC
1Taillight
2Reverse relay
3Starting circuit cut-off relay
4Fuse holder
5Starter relay
6Wire harness
7Breather hose (transmission case)
8Neutral switch lead
9Select lever switch
0Overflow hose
ABattery breather hose
BBand
CBattery negative lead
DReverse switch lead
ÈHold the clamp and ground lead to the crank-
case with a screw.
ÉPass the overflow hose between the engine and
swingarm.
ÊPass the battery breather hose through the
guides.
CABLE ROUTING

–12 –
SPEC
1Inlet hose
2Outlet hose
3Fuel hose
4Breather hose (crankcase)
5Overflow hose
6Guide
7Rear brake cable
8Front brake cable (left)
9Front brake cable (right)
0CDI unit
ABand
ÈPass the breather hose through the hole of han-
dlebar cover and then between the steering col-
umn and fuel tank.
ÉPass the overflow hose left side of the engine
stay.
ÊPass the brake cable inside the swingarm.
CABLE ROUTING