Yamaha VMX12 96 Manual

FOREWORD
This Supplementary Service Manual has been prepared to introduce new service and data for the
VMX12 ’96. For complete service information procedures it is necessary to use this Supplementary
Service Manual together with the following manual.
VMX12 ’86 SERVICE MANUAL: 2EN-ME1
VMX12 ’91 SUPPLEMENTARY SERVICE MANUAL: 2EN-AE1
VMX12 ’93 SUPPLEMENTARY SERVICE MANUAL: 2EN-AE2
VMX12 ’96
SUPPLEMENTARY
SERVICE MANUAL
1995 by Yamaha Motor Co. Ltd.
1st Edition, July 1995
All rights reserved.
Any reprinting or unauthorized use
without the written permission of
Yamaha Motor Co., Ltd.
is expressly prohibited.

NOTE:
CAUTION:
NOTICE
ThismanualwaswrittenbytheYamahaMotorCompanyLtd.primarilyforusebyYamahadealersand
qualified mechanics. It is not possible to put an entire mechanic’s education into one manual, so per-
sonsusingthisbooktoperformmaintenanceandrepairsonYamahamotorcyclesshouldhaveabasic
understanding of the mechanical concepts and procedures inherent in motorcycle repair technology.
Without such knowledge, attempted repairs or service to the motorcycle may render it unfit to use
and/or unsafe.
For USA, California
Thismodelhasbeendesignedand manufactured to performwithincertainspecificationsinregard
toperformanceandemissions.Properservicewiththecorrecttoolsinnecessarytoensurethatthe
motorcyclewilloperateasdesigned.Ifthereisanyquestionaboutaserviceprocedure,itisimpera-
tivethatyoucontact a Yamahadealerfor any service informationchangesthat apply to thismodel.
Thispolicyisintendedtoprovidethecustomerwiththemostsatisfactionfromhismotorcycleandto
conform with federal environmental quality objectives.
Yamaha Motor Company, Ltd. is continually striving to improve all models manufactured by Yamaha.
Modifications and significant changes in specifications or procedures will be forwarded to all Autho-
rized Yamaha dealers and will, where applicable, appear in future editions of this manual.
For USA, California:
ThisServiceManualcontainsinformationregardingperiodicmaintenancetotheemissioncontrolsys-
tem. Please read this material carefully.
PARTICULARY IMPORTANT INFORMATION
This material is distinguished by the following notation.
The Safety Alert Symbol means ATTENTION! BECOME ALERT! YOUR
SAFETY IS INVOLVED!
FailuretofollowWARNINGinstructionscouldresultinsevereinjuryordeathto
the motorcycle operator, a bystander, or a person inspecting or repairing the
motorcycle.
ACAUTION indicates specialprecautions that mustbe taken toavoid damage
to the motorcycle.
NOTE: A NOTE provides key information to make procedures easier or clearer.

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 symbol. (For the
chapter “Periodic inspection and adjustment” the 3rd title appears.)
3rd title 3: This is a final title.
MANUAL FORMAT
Alloftheproceduresinthismanualareorganizedinasequential,step-by-stepformat.Theinformation
has been compiled to provide the mechanic with an easy to read, handy reference that contains com-
prehensive 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.
Anencirclednumeral 6indicatesapartname,andanencircledalphabeticalletterdateoranalign-
ment mark 7, the others being indicated by an alphabetical letter in a box 8.
Aconditionofafaultycomponentwillprecedeanarrowsymbolandthecourseofactionrequired 9.
EXPLODED DIAGRAM
Eachchapterprovidesexplodeddiagramsbeforeeachdisassemblysectionforeaseinidentifyingcor-
rect disassembly and assembly procedures.

23
20
17
15 16
10
12
13
11
14
1
3
5
7
9
2
4
8
6
18 19
21 22
24
EB003000
ILLUSTRATED SYMBOLS
Illustrated symbols 1to 9are printed on top
right of each page and indicate the subject of
each chapter.
1General information
2Specifications
3Periodic inspections and adjustments
4Engine
5Cooling system
6Carburetion
7Chassis
8Electrical
9Troubleshooting
Illustrated symbols 10 to 16 are used to identify
the specifications appearing in the text.
10 Filling fluid
11 Lubricant
12 Special tool
13 Torque
14 Wear limit, clearance
15 Engine speed
16 Ω, V, A
Illustratedsymbols 17 to 22 inthe exploded dia-
grams indicate the types of lubricants and lu-
brication points.
17 Apply engine oil
18 Apply gear oil
19 Apply molybdenum disulfide oil
20 Apply wheel bearing grease
21 Apply lightweight lithium-soap base grease
22 Apply molybdenum disulfide grease
Illustratedsymbols 23 to 24 inthe exploded dia-
gramsindicatethewheretoapplylockingagent
23 and when to install new parts 24 .
23 Apply locking agent (LOCTITE)
24 Replace

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

–1–
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MOTORCYCLE IDENTIFICATION GEN
INFO
NOTE:
NOTE:
NOTE:
GENERAL INFORMATION
MOTORCYCLE IDENTIFICATION
VEHICLE IDENTIFICATION NUMBER
Thevehicleidentificationnumber 1isstamped
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 licensing au-
thority in your state.
FRAME SERIAL NUMBER
The frame serial number 1is stamped into the
right side of the steering pipe.
Starting serial number:
2EN-042101 (EUR)
The first three digits of these numbers are for
model identifications; the remaining digits are
the unit production number.
ENGINE SERIAL NUMBER
Theengineserialnumber 1isstampedintothe
crankcase.
Starting serial number:
2WE-050101 (USA)
2WF-012101 (California)
2EN-042101 (EUR)
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.

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SPECIAL TOOLS GEN
INFO
Oil filter wrench
YU-38411
P/N. 90890-01426
This tool is used to remove and install the oil
filter.
Refer to the list provided to avoid errors when
placing an order.
P/N. YM-jjjjj, YU-jjjjj
YS-jjjjj, YK-jjjjj
ACC-jjjjj
P/N.90890-jjjjj
For
US, CDN
Except for
US, CDN
SPECIAL TOOLS
Theproperspecialtoolsarenecessaryforcom-
plete and accurate tune-up and assembly. Us-
ing the correct special tool will help prevent
damage caused by the use of improper tools or
improvised techniques.
Theshapeandpartnumberusedforthespecial
tooldifferbycountry, so twotypes are provided.
FOR ENGINE SERVICE

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GENERAL SPECIFICATIONS/
MAINTENANCE SPECIFICATIONS SPEC
SPECIFICATIONS
GENERAL SPECIFICATIONS
Model VMX12
Model code: 3JPM (USA)
3JPN (California)
3LRA (EUR)
Engine starting number: 2WE-050101 (USA)
2WF-012101 (California)
2EN-042101 (EUR)
Vehicle identification number: JYA2WEE0 TA050101 (USA)
JYA2WFC0 TA012101 (California)
Frame staring number: 2EN-042101 (EUR)
Basic weight:
With oil and full fuel tank 283 kg (624 lb) (USA)
284 kg (626 lb) (California)
281 kg (620 lb) (EUR)
MAINTENANCE SPECIFICATIONS
ENGINE
Model VMX12
Carburetor:
I.D. Mark
Main jet (M.J)
Main air jet (M.A.J)
Jet needle (J.N)
Needle jet (N.J)
Pilot jet (P.J)
Pilot air jet (P.A.J.1)
Pilot screw (P.S)
Pilot outlet (P.O)
Bypass 1 (B.P.1)
Bypass 2 (B.P.2)
Bypass 3 (B.P.3)
Valve seat size (V.S)
Starter jet (G.S.1)
Starter jet (G.S.2)
Throttle valve size (Th.V)
Fuel level (F.L)
Engine idling speed
Vacuum pressure at idling speed
1FK02(USA),2WF02(California),3LR01(EUR)
#152.5 (USA, California), #150 (EUR)
ø2.0
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)

–4–
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MAINTENANCE SPECIFICATIONS SPEC
ELECTRICAL
Model VMX12
Rectifier:
Model/manufacturer
Capacity
Withstand Voltage
SH662-12/SHINDENGEN
25 A
200 V
Electric starter system:
Type
Starter motor:
Model/manufacturer
Output
Brush overall length
<Limit>
Commutator diameter
<Wear limit>
Mica undercut
Starter switch:
Model/manufacturer
Amperage rating
Coil winding resistance
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/HITACHI
100 A
3.9 4.7 Ωat 20_C (68_F)
Thermostatic switch:
Model/manufacturer 2EL (USA), 47X (California, EUR)/
NIHON THERMOSTAT

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ENGINE OIL REPLACEMENT INSP
ADJ
NOTE:
PERIODIC INSPECTION AND
ADJUSTMENT
ENGINE
ENGINE OIL REPLACEMENT
1. Starttheengineandletitwarmupforseveral
minutes.
2. Stop the engine and place an oil pan under
the drain bolt.
3. Remove:
SOil filler cap 1
4. Remove:
SDrain bolt 1(with gasket)
Drain the crankcase of its oil.
5. If the oil filter is to be replaced during this oil
change,removethe following partsandrein-
stall them.
Replacement steps:
FRemove the oil filter 1using the oil filter
wrench 2.
Oil filter wrench:
YU-38411, 90890-01426
FApplyengineoiltotheO-ring 3ofthenewoil
filter.
Make sure the O-ring 3is positioned correctly.
FTighten the oil filter using the oil filter wrench.
Oil filter:
18 Nm (1.8 mSkg, 13 ftSlb)

–6–
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ENGINE OIL REPLACEMENT INSP
ADJ
NOTE:
NOTE:
CAUTION:
6. Install:
SDrain bolt
Drain bolt:
43 Nm (4.3 mSkg, 31 ftSlb)
Always use a new gasket.
7. Fill:
SCrankcase
Recommended oil:
At 5_C (40_F) or higher A:
SAE 20W40 type SE motor oil
At 15_C (60_F) or lower B:
SAE 10W30 type SE motor oil
Oil quantity:
Total amount:
4.7 L (4.1 lmp qt, 5.0 US qt)
Periodic oil change:
3.5 L (3.1 lmp qt, 3.7 US qt)
With oil filter replacement:
3.8 L (3.3 lmp qt, 4.0 US qt)
Recommended oil classification: API Service
“SE”, “SF” and “SG” type or equivalent (e.g.
“SF-SE”, “SF-SE-CC”, “SF-SE-SD” etc.).
SDo not add any chemical additives.
Engine oil also lubricates the clutch and
additives could cause clutch slippage.
SDo not allow foreign material to enter the
crankcase.
8. Install:
SOil filler cap
9. Warm up the engine for a few minutes, then
stop the engine.
10. Inspect:
SEngine (for oil leaks)
SOil level

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INSPECTION AND REPAIR ENG
CAUTION:
NOTE:
ENGINE OVERHAUL
INSPECTION AND REPAIR
CRANKSHAFT AND CONNECTING ROD
1. Measure:
SRunout (crankshaft)
Out of specification Replace.
Runout:
Less than 0.03 mm (0.0012 in)
2. Inspect:
SMain journal surfaces
SCrank pin surfaces
SBearing surfaces
Wear/Scratches Replace.
3. Measure:
SOil clearance (main journal)
Out of specification Replace bearing.
Oil clearance:
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.
FClean the bearings, main journals and bear-
ing portions of the crankcase.
FPlacethecrankcase(upper)onabenchinan
upside down position.
FInstall the upper half of the bearings and the
crankshaft into the crankcase (upper).
Aligntheprojectionofthebearingwiththenotch
in the crankcase.

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INSPECTION AND REPAIR ENG
NOTE:
NOTE:
CAUTION:
FPut a piece of Plastigaugeon each main
journal.
Do not put the Plastigaugeover the oil hole in
the main journal of the crankshaft.
FInstall the lower half of the bearings into the
crankcase (lower) and assemble the crank-
case halves.
SAlign the projection of the bearing with the
notch in the crankcase.
SDo not move the crankshaft until the oil clear-
ance has been completed.
FTighten the bolts to specification in the tight-
ening sequence cast on the crankcase.
Bolt (Crankcase-M10):
40 Nm (4.0 mSkg, 29 ftSlb)
*With a washer
FRemovethecrankcase(lower)andlowerhalf
of the bearing.
FMeasure the compressed Plastigauge
width aon each main journal.
Ifoil clearanceis out of specification, select a
replacement bearing.
4. Measure:
SOil clearance (crank pin)
Out of specification Replace bearing.
Oil clearance:
0.021 0.039 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.

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E
INSPECTION AND REPAIR ENG
NOTE:
NOTE:
CAUTION:
FClean the bearings, crank pins and bearing
portions of the connecting rods.
FInstall the upper half of the bearing into the
connecting rod and lower half of the bearing
into the connecting rod cap.
Aligntheprojectionofthebearingwiththenotch
of the cap and connecting rod.
FPut a piece of Plastigaugeon the crank pin.
FAssemble the connecting rod halves.
SDo not move the connecting rod or crankshaft
until the oil clearance measurement has been
completed.
SApply molybdenum disulfide grease to the
bolts, threads and nut seats.
SMake sure the “Y” marks on the connecting
rods face the left side of the crankshaft.
SMakesurethatthelettersonbothcomponents
align to from a perfect character.
FTighten the nuts.
Nut:
36 Nm (3.6 mSkg, 25 ftSlb)
Tighten to full torque specification without
pausing. Apply continuous torque between
3.0 and 3.8 mSkg. Once you reach 3.0 mSkg,
DO NOT STOP TIGHTENING until final
torque is reached. If tightening is inter-
ruptedbetween3.0and 3.8 mSkg, loosen nut
to less than 3.0 mSkg and start again.
FRemove the connecting rods and bearings.
FMeasure the compressed Plastigauge
width aon each crank pin.
Ifoil clearanceis out of specification, select a
replacement bearing.

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E
INSPECTION AND REPAIR ENG
5. Select:
SMain journal bearing (J1J4)
SCrank pin bearing (P1P2)
Selection of bearings:
Example 1: Main journal bearing
FIf “J1” on the crankcase is “6” and “1” on the
crankweb, then the bearing size for “J1” is:
Bearing size of J1:
Crankcase J1– Crankweb J1=
6 – 1 = 5 (Yellow)
BEARING COLOR CODE
1 Blue
2 Black
3 Brown
4 Green
5 Yellow
6 Pink
7 Red
Example 2: Crank pin bearing
FIf “P1” on the connecting rod is “4” and “2” on
the crankweb, then the bearing size for “P1”
is:
Bearing size of P1:
Connecting rod P1– Crankweb P1=
4 – 2 = 2 (Black)
BEARING COLOR CODE
1 Blue
2 Black
3 Brown
4 Green
5 Yellow
6 Pink

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INSPECTION AND REPAIR ENG
NOTE:
BALANCER SHAFT
1. Measure:
SOil clearance (balancer shaft bearing)
Out of specification Replace bearing.
Oil clearance:
0.020 0.048 mm
(0.0008 0.002 in)
Measurement steps:
FClean the bearings, balancer shaft and bear-
ing portions of the crankcase.
FPlacethecrankcase(upper)onabenchinan
upside down position.
FInstall the upper half of the bearings and the
balancer shaft into the crankcase (upper).
FPut a piece of Plastigaugeon each balanc-
er shaft journal.
FInstall the lower half of the bearings into the
crankcase (lower) and assemble the crank-
case halves.
Do not move the balancer shaft until the oil
clearance measurement has been completed.
FTighten the bolts to specification in the tight-
ening sequence cast on the crankcase.
Bolt (crankcase-M8):
24 Nm (2.4 mSkg, 17 ftSlb)
FRemovethecrankcase(lower)andlowerhalf
of the bearings.
FMeasure the compressed Plastigauge
width aon each balancer shaft journal. If oil
clearance is out of specification, select a re-
placement bearing.

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E
INSPECTION AND REPAIR ENG
2. Select:
SBalancer shaft bearing
Selection of bearings:
Example:
FIf “J5” on the crankcase is “6” and “2” on the
balancer shaft, then the bearing size for “J5”
is:
Bearing size of J5:
Crankcase J5– Balancer shaft No. =
6 – 2 = 4 (Green)
BEARING COLOR CODE
1 Blue
2 Black
3 Brown
4 Green
5 Yellow
6 Pink
7 Red