Yamaha VMX12H Manual

VMXl2N,
NC~K, KC

LIT - 1 161 6 - 1 0-1 2

FOREWORD
This Supplementary Service Manual has been prepared to introduce new service and data
for the VMX12H/VMX12HC. For complete service information procedures
it is necessary to
use this Supplementary Service Manual together with the following manual.
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VMX12N SERVICE MANUAL:2WE - 28197 - 10
VMXl2F SUPPLEMENTARY SERVICE MANUAL:2WE
- 28197 - 11
I I
VMX 12H/VMX12HC
SUPPLEMENTARY
SERVICE
MANUAL
01995 by Yamaha Motor Co. Ltd.
1st Edition, July 1995
All rights resewed.
Any reprinting or unauthorized use
without the written permission
of
Yamaha Motor Co., Ltd.
is expressly prohibited.

NOTICE ,
This model has been designed and manufactured to perform within certain specifications
in regard to performance and emissions. Proper service with the correct tools in neces -
sary to ensure that the motorcycle will operate as designed. If there is any question about
information changes that apply to this model. This policy is intended to provide the cus
-
tomer with the most satisfaction from his motorcycle and to conform with federal envi -
a service procedure, it is imperative that you contact a Yamaha dealer for any service
, ronmental quality objectives.
NOTE:
For USA, California:
This Service Manual contains information regarding periodic maintenance to the emission
control system. Please read this material carefully.
PARTICULARY IMPORTANT INFORMATION
This material is distinguished by the following notation.
a SAFETY IS INVOLVED!
The Safety Alert Symbol means ATTENTION! BECOME ALERT! YOUR
Failure to follow WARNING instructions could result
in severe injury or
death to the motorcycle operator, a bystander, or a person inspecting
or repairing the motorcycle.
A CAUTION indicates special precautions that must be taken to avoid
damage to the motorcycle.
A NOTE provides key information to make procedures easier or clearer. NOTE:

HOW TO USE THIS MANUAL
CONSTRUCTION OF THIS MANUAL
This manual consists of chapters for the main categories of subjects. (See " Illustrated sym-
bo Is "
1st title This is a chapter with its symbol on the upper right of each page.
2nd title This title appears on the upper of each page on the left of the chapter
symbol. (For the chapter
" Periodic inspection and adjustment " the 3rd
title appears.)
This is a final title.
3rd title
MANUAL FORMAT
All of the procedures in this manual are organized in a sequential, step - by - step format. The
information has been compiled to provide the mechanic with an easy to read,
handy refer -
ence that contains comprehensive explanations of all disassembly, repair, assembly, and
inspections.
A set of particularly important procedure is placed between a line of asterisks
each procedure preceded by
IMPORTANT FEATURES
Data and a special tool are framed in a box preceded by a relevant symbol
An encircled numeral indicates a part name, and an encircled alphabetical letter data or
A condition of a faulty component will precede an arrow symbol and the course of action
an alignment mark the others being indicated by an alphabetical letter in a box
n required
EXPLODED DIAGRAM
Each chapter provides exploded diagrams before each disassembly section for ease in identi -
fying correct disassembly and assembly procedures.
-
- -
....
........ ............................
I'

8
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EB003000
ILLUSTRATED SYMBOLS
Illustrated symbols to are printed on
top right of each page and indicatethe sub
-
ject of each chapter.
General information
Specifications
Periodic inspections and adjustments
Engine
Cooling system
Carburetion
Chassis
Electrical
Troubleshooting
Illustrated symbols to are used to
identify the specifications appearing in the
text.
Filling fluid
Lubricant
Special tool
@Wear limit, clearance
Engine speed
V, A
Illustratedsymbols to in the exploded
diagrams indicate the types
of lubricants
and lubrication points.
Apply engine oil
Apply gear oil
Apply wheel bearing grease
Apply lightweight lithium - soap base grease
Apply molybdenum disulfide grease
Illustrated symbols to in the exploded
diagrams indicate the where
to apply locking
agent and when to install new parts
Apply locking agent
Replace
Apply molybdenum disulfide oil

. - .
CONTENTS
GENERAL INFORMATION .............................................................................. 1
MOTORCYCLE IDENTIFICATION
............................................................ 1
VEHICLE IDENTIFICATION NUMBER
................................................ 1
FRAME SERIAL NUMBER .................................................................. 1
ENGINE SERIAL NUMBER ................................................................. 1
SPECIAL TOOLS .....................................................................................
2
SPECIFICATIONS ............................................................................................ 3
GENERAL SPECIFICATIONS .................................................................. 3
MAINTENANCE SPECIFICATIONS ........................................................ 3
ENGINE ............................................................................................... 3
ELECTRICAL ........................................................................................ 4
PERIODIC INSPECTION AND ADJUSTMENT ................................................ 5
ENGINE .................................................................................................... 5
ENGINE OIL REPLACEMENT .............................................................. 5
ENGINE OVERHAUL ...................................................................................... 7
INSPECTION AND REPAIR ..................................................................... 7
CRANKSHAFT AND CONNECTING ROD .......................................... 7
BALANCER SHAFT ........................................................................... 11
MIDDLE GEAR SERVICE
....................................................................... 13
CHASSIS ........................................................................................................ 14
SHAFT DRIVE ......................................................................................... 14

GEN
MOTORCYCLE IDENTIFICATION
GENERAL INFORMATION
MOTORCYCLE IDENTIFICATION
VEHICLE IDENTIFlCATlON NUMBER
The vehicle identification number is
stamped into the right side of
the steering
pipe.
Starting serial number:
JYA2WEE0 TA050101 (USA)
JYA2WFC0 TA012101 (California)
The vehicle identification number is used to
identify your motorcycle and may be used
to register your motorcycle
with the licens -
ing authority in your state.
FRAME SERIAL NUMBER
The frame serial number is stamped into
the right side of the steering pipe.
Starting serial number:
1 2EN - 042101 (EUR)
I I
NOTE:
The first three digits of these numbers are
for model identifications; the remaining
digits are
the unit production number.
ENGINE SERIAL NUMBER
The engine serial number is stamped
into
the crankcase.
Starting serial number:
2WE
- 050101 (USA)
2WF
- 012101 (California)
I
2EN - 042101 (EUR)
NOTE:
The first three digits of these numbers are
for model identification; the remaining
digits are the unit production number.
Designs and specifications are subject to
change without notice.
-1-

SPECIAL TOOLS GEN
SPECIAL TOOLS
Refer to the list provided to avoid errors
The proper special tools are necessary for
complete and accurate tune
- up and assem -
bly. Using the correct special tool will help
prevent damage caused by the use of
improper tools or improvised techniques.
The shape and part number used for the
special tool differ by country,
so two types
are provided.
FOR ENGINE SERVICE
when placing an order.
P/N. 90890 -
YM -
Except for
US, CDN
Oil filter wrench
YU - 38411
P/N 1 426
This tool is used to remove and install the oil
I filter.
-2-

/ -
Model
Model code:
Engine starting number:
Vehicle identification number:
Frame starting number:
Basic weight:
With
oil and full fuel tank
GENERAL SPECIFICATIONS/
MAINTENANCE SPECIFICATIONS
VMX12
3JPM (USA)
3JPN (California)
3LRA (EUR)
2WF
- 012101 (California)
JYA2WEE0*TA050101 (USA)
JYA2WFC0
* TA0 12 1 0 1 ( California)
2WE
- 050101 (USA)
2EN
- 042101 (EUR)
2EN
- 042101 (EUR)
283 kg (624
Ib) (USA)
284 kg (626
Ib) (California)
281 kg (620
Ib) (EUR)
SPECIFICATIONS
GENERAL SPECIFICATIONS
MAINTENANCE SPECIFICATIONS
ENGINE
Model
Carbu
I. D. Mark
Main jet
Main air jet
Jet needle
Needle jet
Pilot jet
Pilot air jet
Pilot screw
Pilot outlet
Bypass
1
Bypass 2
Bypass 3
Valve seat size
Starter jet
Starter jet
Throttle valve size
Fuel level
Engine idling speed
Vacuum pressure at idling speed
(N.J)
(P.J)
(P.A.J.
1 )
(PS)
(P.O)
(B.P.l)
(B.P.2)
(B.P.3)
(V.S)
(G.S.1)
(G.S.2)
(Th.V)
(F.L)
VMX12
1FK 02 (USA), 2WF 02 (California),
3LR 01 (EUR)
#152.5 (USA, California), #150 (EUR)
82.0
5EZ43-1 (USA), 5EZ50-1 (California),
5EZ19-3 (EUR)
Y
- 0
#37.5 (USA, California), #42.5 (EUR)
#90 (USA),#100(California), #95 (EUR)
2
- 1/4 (USA), 3 (California), 2 - 1/2 (EUR)
0.9
0.8
0.8
0.9
1.5
#45
#0.8
#125 (USA, EUR), #130 (California)
15
~ 17 mm (0.59 ~ 0.66 in)
950 ~ 1,050 r/min (USA, EUR),
1,050 ~ 1,150 r /min (California)
26.7 kPa (200 mmHg, 7.87 in Hg) (USA, EUR)
33.3 kPa (250 mmHg, 9.84
in Hg) (California)
-3-

MAINTENANCE SPECIFICATIONS
Model
Rectifier:
Model
/ manufacturer
Capacity
Withstand Voltage
Electric starter system:
ELECTRICAL
VMX12
SH662-12
/ SHINDENGEN
25 A
200 v
TY Pe
Starter motor:
Model
/ manufacturer
output
Brush overall length
<Lim it>
Commutator diameter
<Wear
I i mit>
Mica undercut
Starter switch:
Model
/ manufacturer
Amperage rating
Coil winding resistance
Thermostatic switch
:
Model / manufacturer
Constant mesh type
SM
- 13 / MITSUBA
0.65
kW
12.5 mm (0.49 in)
<5.0
mm (0.20 in)
28 mm (1.10 in)
<27 mm (1.06 in)>
0.7 mm (0.03 in)
MS5D-191/ HlTACHl
100 A
3.9 ~ 4.7 at 20°C (68°F)
2EL (USA), 47X (California, EUR) /
NIHON THERMOSTAT
-4-

ENGINE OIL REPLACEMENT
/ ---
PERIODIC INSPECTION AND
ADJUSTMENT
ENGINE
ENGINE OIL REPLACEMENT
1.Start the engine and let it warm up for
2.Stop the engine and place an oil pan
severa
I mi n
under the drain bolt.
3.Remove:
Oil filler cap
4. Remove:
Drain bolt (with gasket)
Drain the crankcase of its oil.
the oil filter is to be replaced during this
oil change, remove the following parts
and reinstall them.
Replacement steps:
the oil filter using the oil filter
wrench
Oil filter wrench:
YU-38411,90890-01426
engine oil to the O - ring of the
new oil filter.
NOTE:
Make sure the O - ring is positioned cor -
rectly.
the oil filter using the oil filter
wrench.
Oil filter:
18 Nm (1.8 m kg, 13
ft Ib)
I
-5-

ENGINE OIL REPLACEMENT
Drain bolt:
43Nm(4.3m-kg,31ft• Ib)
I 30 40 50 60 " F
0 5 10 15°C 0 5 10 15°C
NOTE:
Always use
a new gasket.
7.Fill:
Crankcase
Recommended oil:
At 5°C (40°F)or higher
At 15°C(60°F)or lower
SAE 20W40 type SE motor oil
SAE 10W30type SE motor oil
4.7
L (4.1 Imp qt, 5.0 US qt)
3.5 L (3.1 Imp qt, 3.7 US qt)
3.8 L (3.3 Imp qt, 4.0 US qt)
Oil quantity:
Total amount:
Periodic oil change:
With oil filter replacement:
NOTE:
Recommended oil classification:
API Ser -
vice "SE", "SF" and " SG " type or equiva-
I en t
(e. g . "S F - S E" , "S F - S E - CC" ,
"SF - S E -
SD " etc.).
Do not add any chemical additives.
Engine oil also lubricates the clutch and
additives could cause clutch slippage.
Do not allow foreign material to enter the
crankcase.
8.1 nsta I I:
9.Warm up the engine for a few minutes,
then stop the engine.
10.lnspect:
Engine (for oil leaks)
Oil level
Oil filler cap
-6-

INSPECTION AND REPAIR
ENGINE OVERHAUL
INSPECTION AND REPAIR
CRANKSHAFT AND CONNECTING ROD
1.Measure:
Runout (crankshaft)
Out
of specification Replace.
Runout:
Less than
0.03 mm (0.0012 in)
2.1 nspect:
Main journal surfaces
Crank pin surfaces
Bearing surfaces
Wear/Scratches Replace.
3. Measure:
Oil clearance (main journal)
Out of specification Replace bearing.
0.020 ~ 0.038 mm
(0.0008 ~ 0.0015 in)
Measurement steps:
Do not interchange the bearings and con
-
necting rod. They must be installed in their
original positions, or the correct oil clear
-
ance may not be obtained causing engine
damage.
the bearings, main journals and
bearing portions of the crankcase.
the crankcase (upper) on a bench in
an upside down position.
the upper half of the bearings and
the crankshaft into the crankcase (upper).
Align the projection of the bearing with the
notch
in the crankcase.
N O TE :
-7-

INSPECTION AND REPAIR
a piece of Plastigauge® on each m ain
journal.
NOTE:
D o not put the Plastigauge® over the oil
hole in the m ain journalof the crankshaft,
 installthe low er halfofthe bearings into
the crankcase (low er)and assem ble the
crankcase halves.
NOTE:
Align the projection of the bearing w ith
the notch in the crankcase.
D o not move the crankshaftuntil the oil
clearance has been com pleted.
 Tighten the bolts to specification in the
tightening sequence cast on the crank-
case.
Bolt(C rankcase-M 10):
40 Nm (4.0 29 ft•lb)
With a w asher
•Remove the crankcase (low er)and low er
halfof the bearing.
M easure the com pressed P lastigauge® ’
widthon each m ain journal.
If oilclearance is out of specification,
select a replacem ent bearing.
4.M easure:
 Oilclearance (crank pin)
Outofspecification R eplace bearing.
(0 .0008 0.0015 in
M easurem ent steps:
Do not interchange the bearings and con-
necting rod. They m ust be installed in their
original positions, or the correct oilclear-
ance m ay not be obtained causing engine
dam age.

/ ---
INSPECTION AND REPAIR
the bearings, crank pins and bear -
ing portions of the connecting rods.
the upper half of the bearing into
the connecting rod and lower half of the
bearing into the connecting rod cap.
NOTE:
Align the projection of the bearing with the
notch of the cap and connecting rod.
a piece of Plastigauge® on the crank
the connecting rod halves.
pin.
NOTE:
Do not move the connecting rod or crank -
shaft until the oil clearance measurement
has been completed.
Apply molybdenum disulfide grease to
the bolts, threads and nut seats.
Make sure the "Y" marks on the connect -
ing rods face the left side of the crank -
shaft.
Make sure that the letters on both compo -
nents align to from a perfect character.
the nuts.
(3.6 mkg, 25 I
Tighten to full torque specificationwithout
pausing. Apply continuous torque between
3.0 and 3.8 Once you reach 3.0
DO NOT STOP TIGHTENING until final
torque is reached. If tightening is inter
-
rupted between 3.0 and 3.8 loosen
nut to lessthan
3.0 and start again.
Remove the connecting rods and bear -
ings.
Measure the compressed Plastigauge®
width on each crank pin.
If oil clearance is out of specification,
select
a replacement bearing.
-9-

INSPECTION AND REPAIR
P2
Main journalbearing J,)
 Crank pin bearing P,)
Selection of bearings:
Exam ple 1: M ain journal bearing
“J,”on the crankcase is “6” and “1” on
the crankw eb, then the bearing size for
is:
Exam ple 2: Crank pin bearing
on the connecting rod is “4” and
“2” on the crankw eb, then the bearing
size for is:

the bolts to specification in the
tightening sequence cast
on the crank -
case.
Bo It (crankcase-M8) :
24 Nm (2.4 17
the crankcase (lower) and lower
half
of the bearings.
INSPECTION AND REPAIR
BALANCER SHAFT
1.Measure:
Oil clearance (balancer shaft bearing)
Out of specification Replace bearing.
Oil clearance:
0.020 0.048 mm
(0.0008
0.002 in)
Measurement steps:
the bearings, balancer shaft and
bearing portions
of the crankcase.
the crankcase (upper) on a bench in
an upside down position.
the upper half of the bearings and
the balancer shaft into the crankcase
(upper).
a piece of Plastigauge® on each bal -
ancer shaft journal.
the lower half of the bearings into
the crankcase (lower) and assemble the
crankcase halves.
NOTE:
Do not move the.balancer shaft until the oil
clearance measurement has been com-
pleted.
Measure the compressed Plastigauge®
width on each balancer shaft journal. If
oil clearance is out of specification, select
a replacement bearing.
-11-

INSPECTION AND REPAIR
I J5 J6 I
2.Select:
Balancer shaft bearing
Selection of bearings:
Example:
on the crankcase is " 6 " and " 2 " on
the balancer shaft, then the bearing
size
for " J, " is:
Bearing size of
Crankcase - Balancer shaft No.
6 - 2 4 (Green)
BEARING COLOR CODE
1 Blue
I 2 I Black
3 Brown
4 Green
Yellow
Pink
- 12-

MIDDLE GEAR SERVICE
Universaljoint
Dust seal
Housing
O - ring @Thrust washer
Bearing Retainer
Collapsible collar
Bearing
Middle drive shaft
Middle driven pinion gear
Spring seat
Damper spring
Damper cam
Middle drive pinion gear
- 13-