Yamaha YP250 User Manual

EB000000

YP250

SERVICE MANUAL1996 by Yamaha Motor Co., Ltd.

1st Edition, January 1996

All rights reserved. Any reprinting 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 scooter has a basic understanding of the mechanical ideas and the procedures of scooter repair. Repairs attempted by anyone without this knowledge are likely to render the scooter unsafe and unfit for use.

Yamaha Motor Company, Ltd. is continually striving to improve all its models. Modifications and significant changes in specifications or procedures will be forwarded to all authorized Yamaha dealers and will appear in future editions of this manual where applicable.

NOTE:

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 scooter operator, a bystander or a person inspecting or repairing the scoot-
		er.
		A CAUTION indicates special precautions that must be taken to avoid damage
	CAUTION:
		to the scooter.
	NOTE:
		A NOTE provides key information to make procedures easier or clearer.

YP002000

HOW TO USE THIS MANUAL

MANUAL ORGANIZATION

This manual consists of chapters for the main categories of subjects. (See ªIllustrated symbolsº)

1st title 1 : This is the title of the chapter with its symbol on 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 accompanied by corresponding illustrations.

EXPLODED DIAGRAMS

To heps identify parts and clarify procedure steps, there are exploded diagrams at start of each removal and disassembly section.

1.An easy-to-see exploded diagram 4 is provided for disassembly and assembly jobs.

2.Numbers 5 are given in the order of 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 7 accompanies 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 8 are given in addition to the exploded diagram and the job instruction chart.

2

1

4

3

5	8

6

6

7

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

EB003000

ILLUSTRATED SYMBOLS

Illustrated symbols 1 to 9 are designed as thumb tabs to indicate the chapter's number and content.

1General information

2Specifications

3Periodic inspection and adjustment

4Engine

5Cooling system

6Carburetion

7Chassis

8Electrical

9Troubleshooting

Illustrated symbols 10 to 17 are used to identify the specifications appearing in the text.

10Possible to maintain with engine mounted

11Filling fluid

12Lubricant

13Special tool

14Tightening

15Wear limit, clearance

16Engine speed

17Ω, V, A

Illustrated symbols 18 to 23 in the exploded diagrams indicate the types of lubricants and lubrication points.

18Apply engine oil

19Apply gear oil

20Apply molybdenum disulfide oil

21Apply wheel bearing grease

22Apply lightweight lithium-soap base grease

23Apply molybdenum disulfide grease

Illustrated symbols 24 to 25 in the exploded diagrams indicate the where to apply locking agent 24 and when to install new parts 25 .

24 Apply locking agent (LOCTITE )

25 Use new one

INDEX

	GENERAL INFORMATION
		GEN	1
		INFO
	SPECIFICATIONS
		SPEC	2
	PERIODIC INSPECTION AND
		INSP	3
	ADJUSTMENT
		ADJ
	ENGINE OVERHAUL
		ENG	4
	COOLING SYSTEM
		COOL	5
	CARBURETION
		CARB	6
	CHASSIS
		CHAS	7
	ELECTRICAL
		ELEC	8
	TROUBLESHOOTING
		TRBL	9
		SHTG

CHAPTER 1

GENERAL INFORMATION

SCOOTER IDENTIFICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 VEHICLE IDENTIFICATION NUMBER (for E) . . . . . . . . . . . . . . . . . . . 1-1 FRAME SERIAL NUMBER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 ENGINE SERIAL NUMBER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 MODEL LABEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 OIL INDICATOR LIGHT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 AUTO CHOKE SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 IGNITION CIRCUIT CUT-OFF SYSTEM . . . . . . . . . . . . . . . . . . . . . . . 1-3 IMPORTANT INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4 PREPARATION FOR REMOVAL PROCEDURES . . . . . . . . . . . . . . . 1-4 REPLACEMENT PARTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4 GASKETS, OIL SEALS, AND O-RINGS . . . . . . . . . . . . . . . . . . . . . . . . 1-4 LOCK WASHERS/PLATES AND COTTER PINS . . . . . . . . . . . . . . . . 1-5 BEARINGS AND OIL SEALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5 CIRCLIPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5 CHECKING OF CONNECTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6 HOW TO USE THE CONVERSION TABLE . . . . . . . . . . . . . . . . . . . . . 1-7 SPECIAL TOOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8

GEN

SCOOTER IDENTIFICATION INFO

YP100000

GENERAL INFORMATION

SCOOTER IDENTIFICATION

YP100010

VEHICLE IDENTIFICATION NUMBER (for E)

The vehicle identification number 1 is stamped into the right side of the frame.

NOTE:

The vehicle identification number is used to identify your scooter and may be used to register your scooter with the licensing authority in your country.

YP100020

FRAME SERIAL NUMBER (except for E)

The frame serial number 1 is stamped into the right side of the frame.

EB100030

ENGINE SERIAL NUMBER

The engine serial number 1 is stamped into the crankcase.

NOTE:

Designs and specifications are subject to change without notice.

MODEL LABEL

The model label 1 is affixed under the seat. This information will be needed to order spare parts.

1-1

GEN

FEATURES INFO

FEATURES

OIL INDICATOR LIGHT

Function

Pulses (travel distance signals) from the speedometer are counted and cause the oil indicator light to come on at 1,000 km for the first time and thereafter every 3,000 km. In this way, this light indicates the time for oil change.

Circuit diagram

Engine stop

Main switch Ignitor unit switch

Oil indicator light

	Reset button
Fuse
Battery	Meter		Oil indicator light
		C.P.U	Reset button

Resetting procedure

Travel distance can be reset if the reset button is held down for 2 to 5 seconds with the main switch ªONº.

1)If the ªresettingº is done while the oil light is on, the oil indicator light goes off for resetting confirmation.

2)If the ªresettingº is done while the oil light is off, the oil indicator light comes on for 1.4 seconds for resetting confirmation.

Failure diagnosis

1)Checking oil indicator light for breakage

This oil indicator light is kept on for 1.4 seconds immediately after the main switch is turned on, thereby checking the bulb for breakage.

2)In case of meter pulse failure

If travel distance signals are not detected during running, the oil indicator light flashes and gives a warning of meter signal failure.

NOTE:

This circuit may be activated if the engine is accelerated without load with the mainestand put up.

Battery tending to discharge.

If the starting motor is run with the battery tending to discharge, the oil indicator light may come on (for 1.4 seconds), but this is noting abnormal.

In this case recharge or replace battery.

This light comes on if battery charging becomes poor, thereby causing the engine to run as low as about 200 rpm against 600 rpm or so,

1-2

FEATURES

AUTO-CHOKE SYSTEM

GEN INFO

This system is the parallel connection of the ignitor unit circuit and the thermo switch as shown, detecting the engine temperature, and facilitates the restarting with the warm engine.

Circuit diagram	Igniter unit
	Main switch

		Fuse	Thermo
			switch			Ignition
					C.P.U
	Battery
			Auto-choke
Auto-choke operation
Engine condition		Start with the		Crank with the		Crank with the		Restart with the
		cold engine		cold engine		warm engine		warm engine
Thermo switch		OFF		OFF		ON		ON
Ignitor unit circuit		OFF		ON		ON		OFF
Auto-choke		Activates		Activates		Not activate		Not activate

IGNITION CIRCUIT CUT-OFF SYSTEM

A sidestand circuit is added to the existing electric starting circuit, thereby controlling the starter motor operation and the ignition system of the igniter unit.

Circuit diagram

	Main switch			Engine stop switch
				Brake
				switch			Ignitor unit
Fuse
	Starter relay				Relay
Battery		Starter		Start	Brake light	Sidestand
				switch		switch
		motor
Operating mode
Sidestand switch		Operation of brake			Operation of starter			Operation of igniter
			light		motor			unit control
OFF			ON		Not operated			Misfire
(Sidestand in use)			OFF		Not operated			Misfire
ON			ON		Operated			Ignited
(Sidestand folded in)			OFF		Not operated			Ignited (ridden)

1-3

GEN

IMPORTANT INFORMATION INFO

EB101000

IMPORTANT INFORMATION

PREPARATION FOR REMOVAL PROCEDURES

1.Remove all dirt, mud, dust and foreign material before removal and disassembly.

2.Use proper tools and cleaning equipment.

3.Refer to the ªSPECIAL TOOLSº section.

4.When disassembling the machine, always keep mated parts together. This includes gears, cylinders, pistons and other parts that have been ªmatedº through normal wear. Mated parts must always be reused or replaced as an assembly.

5.During machine disassembly, clean all parts and place them in trays in the order of disassembly. This will speed up assembly and allow for the correct installation of all parts.

6.Keep all parts away from any source of fire.

EB101010

REPLACEMENT PARTS

1.Use only genuine Yamaha parts for all replacements. Use oil and grease recommended by Yamaha for all lubrication jobs. Other brands may be similar in function and appearance, but inferior in quality.

EB101020

GASKETS, OIL SEALS AND O-RINGS

1.Replace all gaskets, seals and O-rings when overhauling the engine. All gasket surfaces, oil seal lips and O-rings must be cleaned.

2.Properly oil all mating parts and bearings during reassembly. Apply grease to the oil seal lips.

1-4

GEN

IMPORTANT INFORMATION INFO

OR

EB101030

LOCK WASHERS/PLATES AND COTTER PINS

1.Replace all lock washers/plates and cotter pins after removal. Bend lock tabs along the bolt or nut flats after the bolt or nut has been tightened to specification.

EB101040

BEARINGS AND OIL SEALS

Install bearings and oil seals so that the manufacturer's marks or numbers are visible. When installing oil seals, apply a light coating of lightweight lithium base grease to the seal lips. Oil bearings liberally when installing, if appropriate.

1 Oil seal

CAUTION:

Do not use compressed air to spin the bearings dry. This will damage the bearing surfaces.

1 Bearing

EB101050

CIRCLIPS

1.Check all circlips carefully before reassembly. Always replace piston pin clips after one use. Replace distorted circlips. When installing a circlip 1 , make sure that the sharp-edged corner 2 is positioned opposite the thrust 3 it receives. See sectional view.

4 Shaft

1-5

IMPORTANT INFORMATION

EB801000

GEN INFO

CHECKING OF CONNECTIONS

Dealing with stains, rust, moisture, etc. on the connector.

1.Disconnect: S Connector

2.Dry each terminal with an air blower.

3.Connect and disconnect the connector two or three.

4.Pull the lead to check that it will not come off.

5.If the terminal comes off, bend up the pin 1 and reinsert the terminal into the connector.

6.Connect:

S Connector

NOTE:

The two connectors ªclickº together.

7. Check for continuity with a tester.

NOTE:

DIf there is no continuity, clean the terminals.

DBe sure to perform the steps 1 to 7 listed above when checking the wireharness.

DFor a field remedy, use a contact revitalizer available on the market.

DUse the tester on the connector as shown.

1-6

HOW TO USE THE CONVERSION TABLE

EB201000

GEN INFO

HOW TO USE THE CONVERSION TABLE

All specification data in this manual are listed in SI and METRIC UNITS.

Use this table to convert METRIC unit data to IMPERIAL unit data.
Ex.
METRIC		MULTIPLIER			IMP
**mm		0.03937		=	** in
2 mm		0.03937		=	0.08 in
CONVERSION TABLE
						METRIC TO IMP
				Known			Multiplier		Result
				m kg			7.233		ft lb
Torque				m kg			86.794		in lb
				cm kg			0.0723		ft lb
				cm kg			0.8679		in lb
Weight				kg			2.205		lb
				g			0.03527		oz
				km/hr			0.6214		mph
				km			0.6214		mi
Distance				m			3.281		ft
				m			1.094		yd
				cm			0.3937		in
				mm			0.03937		in
				cc (cm3)			0.03527		oz (IMP liq.)
Volume/				cc (cm3)			0.06102		cu in
Capacity				lit (liter)			0.8799		qt (IMP liq.)
				lit (liter)			0.2199		gal (IMP liq.)
Miscella-				kg/mm			55.997		lb/in
				kg/cm2			14.2234		psi (lb/in2)
neous
				Centigrade			9/5(_C) + 32		Fahrenheit (_F)

1-7

SPECIAL TOOLS

EB102000

GEN INFO

SPECIAL TOOLS

The following special tools are necessary for complete and accurate tune-up and assembly.

Use only the appropriate special tools; this will help prevent damage caused by the use of inappropriate tools or improvised techniques.

When placing an order, refer to the list provided below to avoid any mistakes.

Tool No.	Tool name/Usage	Illustration
90890-01084	Weight
-01085	Rocker arm shaft puller bolt
	These tools are used when removing
	or installing the rocker arm shafts.
90890-01235	Rotor holding tool
	This tool is used to remove the
	flywheel magneto.
90890-01268	Ringnut wrench
	This tool is used to loosen and tighten
	the exhaust and steering ringnut.
90890-01311	Valve adjusting tool
	This tool is necessary for adjusting
	valve clearance.
90890-01312	Fuel level gauge
	This gauge is used to measure the fuel
	level in the float chamber.
90890-01325	Radiator cap tester
-01352	Adaptor
	These tools are used for checking the
	cooling system.
90890-01326	T-handle
-04084	Damper rod holder
	These tool are used for holding the
	damper rod holder when removing or
	installing the damper rod holder.
90890-01337	Clutch spring compressor
-01464	Clutch spring holder arm
	These tools are used for removing the
	nut with holding the compression spring.
90890-01348	Locknut wrench
	This tool is used when removing or
	installing the secondary sheave nut.

1-8

	SPECIAL TOOLS				GEN
					INFO
Tool No.	Tool name/Usage		Illustration
90890-01362	Flywheel puller
	This tool is used for removing the
	rotor.
90890-01367	Fork seal driver weight
-01368	Fork seal driver attachment (ù33)
	This tool is used when installing the
	fork seal.
90890-01384	Oil seal guide
	This tool is used for protecting the oil
	seal lip when installing the secondary
	sliding sheave.
90890-01403	Ring nut wrench
	This tool is used to loosen and tighten
	the steering ring nut.
90890-01701	Sheave holder
	This tool is used for holding the
	secondary sheave.
90890-01996	Cylinder cup installer set
	This tool is used for installing the
	cylinder cup to the master cylinder
	piston.
90890-03079	Thickness gauge
	This tool is used to measure the valve
	clearance.
90890-03081	Compression gauge
	These tools are used to measure the
	engine compression.
90890-03112	Pocket tester
	These instruments are invaluable for
	checking the electrical system.
90890-03113	Engine tachometer
	This tool is needed for detecting
	engine rpm.

1-9

	SPECIAL TOOLS				GEN
					INFO
Tool No.	Tool name/Usage		Illustration
90890-03141	Timing light
	This tool is needed for detecting
	ignition timing.
90890-04101	Valve lapper
	This tool is used for removing and
	installing the lifter and for lapping the
	valve.
90890-04019	Valve spring compressor
-04108	Attachment
	These tools are used when removing
	or installing the valve and the valve
	spring.
90890-04058	Middle shaft bearing driver
-04078	Mechanical seal installer
	These tools are used for installing
	mechanical seal.
90890-06754	Ignition checker
	This instrument is necessary for checking
	the ignition system components.
90890-85505	Yamaha bond No. 1215
	This sealant (bond) is used for crankcase
	mating surface, etc.

1-10

CHAPTER 2.

SPECIFICATIONS

GENERAL SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 MAINTENANCE SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4 ENGINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

CHASSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10 ELECTRICAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14 GENERAL TORQUE SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . 2-16

LUBRICATION POINTS AND GRADE OF LUBRICANT . . . . . . . . . . . . 2-17 ENGINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-17 CHASSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-18 CABLE ROUTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-19

	GENERAL SPECIFICATIONS			SPEC
	SPECIFICATIONS
GENERAL SPECIFICATIONS
Model		YP250
Model code:		4UC 1 (except for CH, A)
		4UD1 (for CH, A)
Dimensions:
Overall length		2,110 mm
Overall width		750 mm
Overall height		1,330 mm
Seat height		700 mm
Wheelbase		1,500 mm
Minimum ground clearance		115 mm
Minimum turning radius		2,600 mm
Basic weight:
With oil and full fuel tank		158 kg
Engine:
Engine type		Liquid-cooled 4-stroke, SOHC
Cylinder arrangement		Forward-inclined single cylinder
Displacement		0.249L (249 cm3)
Bore stroke		69.0 66.8 mm
Compression ratio		10 : 1
Compression pressure (STD)		1,400 kPa (14 kg/cm2, 14 bar) at 500 r/min
Starting system		Electric starter
Lubrication system:		Wet sump
Oil type or grade:
Engine oil
		API STANDERD:
		SE or higher grade

Periodic oil change	1.2 L
Total amount	1.4 L
Transmission oil
Total amount	0.25 L
Radiator capacity
Total amount (including all routes)	1.4 L
Air filter: Carburetor side	Wet type element
Crankcase side	Dry type element
Fuel:
Type	Regular unleaded gasoline
Fuel tank capacity	11 L

2-1

		GENERAL SPECIFICATIONS			SPEC
	Model		YP250
Carburetor:
Type/quantity			Y28V-1A/1
Manufacturer			TEIKEI
Spark plug:
Type			DR8EA
Manufacturer			NGK
Spark plug gap			0.6 X 0.7 mm
Clutch type:			Dry, centrifugal automatic
Transmission:
Primary reduction system			Helical gear
Primary reduction ratio			40/15 (2.666)
Secondary reduction sytem			Sper gear
Secondary reduction ratio			37/16 (2.312)
Transmission type			Single speed automatic (V-belt type)
Operation			Centrifugal automatic type
Single speed automatic			2.20 X 0.88:1
Chassis:
Frame type			Steel tube underbone
Caster angle			28
Trail			103 mm
Tire:
Type			Tubeless
Size	front		110/90-12 64J
	rear		130/70-12 62L
Manufacturer	front		IRC/CHENG SHIN
	rear		IRC/CHENG SHIN
Type	front		MB61/C922
	rear		MB61/C940
Tire pressure (cold tire):
Maximum load-except motorcycle			197 kg
Loading condition A*			0 X 90 kg
	front		175 kPa (1.75 kg/cm2, 1.75 bar)
	rear		200 kPa (2.0 kg/cm2, 2.0 bar)
Loading condition B*			90 X 205 kg
	front		200 kPa (2.0 kg/cm2, 2.0 bar)
	rear		225 kPa (2.25 kg/cm2, 2.25 bar)
High-speed riding
	front		200 kPa (2.0 kg/cm2, 2.0 bar)
	rear		250 kPa (2.5 kg/cm2, 2.5 bar)

*Load is the total weight of cargo, rider, passenger, and accessories.

2-2

		GENERAL SPECIFICATIONS				SPEC
	Model			YP250
Brake:
Front brake	type		Single disc brake
	operation		Right hand operation
Rear brake	type		Drum brake
	operation		Left hand operation
Suspension:
Front suspension			Telescopic fork
Rear suspension			Unit swing
Shock absorber:
Front shock absorber			Coil spring/Oil damper
Rear shock absorber			Coil spring/Oil damper
Wheel travel:
Front wheel travel			85 mm
Rear wheel travel			90 mm
Electrical:
Ignition system			T.C.I. (Digital)
Generator system			A.C. magneto
Battery type			GT7B-5
Battery capacity			12 V 6 AH
Headlight type:			Quartz bulb (Halogen)
Bulb wattage quantity:
Headlight			12V	60 W/55 W 1
Marker light			12V	4 W 1
Tail/brake light			12V	5 W/21 W 1
Flasher light			12V	21W 4
Meter light			12V	1.7W 4
High beam indicator light			12V	3.4 W 1
Oil indicator light			12V	1.7 W 1
Turn indicator light			12V	3.4 W 2
License light			12V	5 W 1

2-3

MAINTENANCE SPECIFICATIONS SPEC

MAINTENANCE SPECIFICATIONS

ENGINE

Item			Standard	Limit
Cylinder head:
Warp limit			SSS	0.03 mm
Cylinder:
Bore size			69.000 X 69.005 mm	69.1 mm
Out of round limit			SSS	0.03 mm
Camshaft:
Cam dimensions
Intake	ªAº		36.545 X 36.645 mm	36.45 mm
	ªBº		30.021 X 30.121 mm	29.92 mm
	ªCº		6.524 mm	SSS
Exhaust	ªAº		36.547 X 36.647 mm	36.45 mm
	ªBº		30.067 X 30.167 mm	29.97 mm
	ªCº		6.48 mm	SSS
Camshaft runout limit			SSS	0.03 mm
Cam chain:
Cam chain type/No. of links			DID SCSA-0404A SDH/104	SSS
Rocker arm/rocker armshaft:
Rocker arm inside diameter			12.000 X 12.018 mm	12.03 mm
Rocker shaft outside diameter			11.981 X 11.991 mm	11.995 mm
Rocker arm-to-rocker armshaft
clearance			0.009 X 0.012 mm	SSS
Valve, valve seat, valve guide:
Valve clearance (cold)		IN	0.08 X 0.12 mm	SSS
		EX	0.16 X 0.20 mm	SSS
Valve dimensions

	Face Width		Seat Width	Margin Thickness
ªAº head diameter	IN		33.9 X 34.1 mm		SSS
	EX		28.4 X 28.6 mm		SSS
ªBº face width	IN		3.394 X 3.960 mm		SSS
	EX		3.394 X 3.960 mm		SSS
ªCº seat width	IN		0.9 X 1.1 mm		SSS
	EX		0.9 X 1.1 mm		SSS
ªDº margin thickness	IN		0.8 X 1.2 mm		SSS
	EX		0.8 X 1.2 mm		SSS
Stem outside diameter	IN		5.975 X 5.990 mm		5.94 mm
	EX		5.960 X 5.975 mm		5.92 mm
Guide inside diameter	IN		6.000 X 6.012 mm		6.05 mm
	EX		6.000 X 6.012 mm		6.05 mm

2-4

	MAINTENANCE SPECIFICATIONS			SPEC
Item		Standard		Limit
Stem-to-guide clearance	IN	0.010 X 0.037 mm		0.08 mm
	EX	0.025 X 0.052 mm		0.1 mm
Stem runout limit		SSS		0.01 mm
Valve seat width	IN	0.9 X 1.1 mm		1.6 mm
	EX	0.9 X 1.1 mm		1.6 mm
Valve spring:
Free length (Inner)	IN/EX	38.1 mm		36.1 mm
(Outer)	IN/EX	36.93 mm		35.0 mm
Set length (valve closed)	(Inner) IN/EX	30.1 mm		SSS
	(Outer) IN/EX	31.6 mm		SSS
Compressed pressure	(Inner) IN/EX	7.8 X 9.0 kg		SSS
	(Outer) IN/EX	37.22 X 42.83 kg		SSS
Tilt limit (Inner)	IN/EX	SSS		2.5_/1.7 mm
(Outer)	IN/EX	SSS		2.5_/1.7 mm
Piston:
Piston to cylinder		0.02 X 0.04 mm		0.15 mm
clearance
Piston size ªDº		68.965 X 68.980 mm		SSS
Measuring point ªHº		5 mm		SSS
Piston pin bore		17.004 X 17.015 mm		17.045 mm
inside diameter
Piston pin outside diameter		16.991 X 17.000 mm		16.975 mm
Piston rings:
Top ring:
Type		Barrel		SSS
End gap (installed)		0.15 X 0.30 mm		0.45 mm
Side clearance (installed)		0.04 X 0.08 mm		0.12 mm
2nd ring:
Type		Taper		SSS
End gap (installed)		0.30 X 0.45 mm		0.7 mm
Side clearance		0.03 X 0.07 mm		0.12 mm
Oil ring:
End gap (installed)		0.2 X 0.7 mm		SSS
Crankshaft:

Crank width ªAº	59.95 X 60.00 mm	SSS
Runout limit ªCº	0.03 mm	SSS
Big end side clearance ªDº	0.35 X 0.85 mm	SSS

2-5

	MAINTENANCE SPECIFICATIONS			SPEC
Item		Standard			Limit
Automatic centrifugal clutch:
Clutch shoe thickness		3.0 mm			2.0 mm
Clutch housing inside diameter		135 mm			135.5 mm
Clutch shoe spring free length		28.1 mm			SSS
Weight outside diameter		20 mm			19.5 mm
Clutch ± in revolution		2,100 X 2,700 r/min			SSS
Clutch ± stall revolution		3,700 X 4,700 r/min			SSS
V-belt:
V-belt width		22.6 mm			21.0 mm
Carburetor:
Type		Y28V-1B-1
I.D. mark		4UC 00 [4UD 00 (CH, A)]			SSS
Ventuly outside diameter		ù28			SSS
Main jet	(M.J)	#130			SSS
Main air jet	(M.A.J)	ù0.9			SSS
Jet needle	(J.N)	5D32-3/5			SSS
Throttle valve size	(Th.V)	11_			SSS
Pilot air jet	(P.A.J.1)	ù1.2			SSS
Needle jet	(N.J)	ù2.585			SSS
Pilot outlet	(P.O)	ù0.8			SSS
Pilot jet	(P.J)	#44			SSS
Bypass	(B.P)	0.7 4			SSS
Pilot screw	(P.S)	17/8			SSS
Valve seat size	(V.S)	1.4			SSS
Starter jet 1	(G.S.1)	ù0.45			SSS
Starter jet 2	(G.S.2)	ù0.5			SSS
Float height	(F.H)	27 mm			SSS
Engine idle speed		1,450 X 1,550 r/min			SSS
Intake vacuum		220 X 260 mmHg			SSS
Oil temperature		65 X 75_C			SSS
Cooling water temperature		80_C			SSS
Fuel pump:
Type		Vaccum type			SSS
Model/manufacturer		4HC/MIKUNI			SSS
Oil pump:
Type		Trochoid type			SSS
Tip clearance		0.1 X 0.34 mm			0.4 mm
Side clearance		0.013 X 0.036 mm			0.15 mm
Housing and rotor clearance		0.04 X 0.09 mm			0.15 mm

2-6

MAINTENANCE SPECIFICATIONS				SPEC
Item	Standard				Limit
Radiator:
Type	Cooling fin with electric fan				SSS
Width/height/thickness	140/238/24 mm				SSS
Radiator cap opening pressure	110 X 140 kPa (1.1 X 1.4 kg/cm2,
	1.1 X 1.4 bar)				SSS
Radiator capacity	1.4 L				SSS
Reservoir tank capacity	0.35 L				SSS
Thermostatic valve:
Type/manufacturer	4HC/NIHON THERMOSTAT
Valve opening temperature	80.5 X 83.5_C
Valve full open temperature	95_C
Valve full open lift	3 mm
Item		Size
Bearings and oil seals:
Big end bearing		32 40 20 (needle bearing)
Crankshaft bearing (left)		6306
Crankshaft bearing (right)		63/28
Crankshaft oil seal (left)		SD-30-45-5
Crankshaft oil seal (right)		S7-14-27-6
Water pump bearing		6000
Water pump oil seal		S-10-21-5
Main axle bearing (left)		15NQ2815
Main axle bearing (right)		15NQ2815
Drive axle bearing (left)		6303
Drive axle bearing (right)		6272
Drive axle oil seal		SD8-32-52-7
Camshaft bearing (left)		6005
Camshaft bearing (right)		6202Z
Primary drive gear bearing (left)		6205
Primary drive gear bearing (right)		6302
Primary drive gear oil seal		SD8-32-52-7

2-7

MAINTENANCE SPECIFICATIONS SPEC

TIGHTENING TORQUES

ENGINE

			Thread		Tightening
	Part to be tightened	Part name		Q'ty	torque		Remarks
			size
					Nm	mSkg
	Oil check bolt	Ð	M6	1	7	0.7
	Exhaust pipe stud bolt	Ð	M8	2	13	1.3
	Spark plug	Ð	M12	1	18	1.8
	Cam sprocket cover	Bolt	M6	2	10	1.0
	Cylinder head and cylinder	Nut	M8	4	22	2.2
	Cylinder head and cylinder	Bolt	M6	2	10	1.0
	(Cam chain side)
	Valve cover	Bolt	M6	5	10	1.0
	Rotor	Nut	M16	1	80	8.0
	Valve adjuster locknut	Nut	M6	2	14	1.4
	Cam shaft bearing stopper	Bolt	M6	2	8	0.8
	Cam sprocket	Bolt	M10	1	60	6.0
	Cam chain tensioner
	(Body)	Bolt	M6	2	10	1.0
	(Plug)	Bolt	M8	1	8	0.8
	Guide stopper 2	Bolt	M6	1	10	1.0
	Water pump housing cover	Bolt	M6	3	10	1.0
	Hose joint	Ð	M6	2	7	0.7
	Thermostatic valve cover	Bolt	M6	2	10	1.0
	Filler neck supporting	Bolt	M5	1	5	0.5
	Oil pump	Screw	M6	2	7	0.7
	Oil pump cover	Bolt	M3	1	1	0.1
	Drain plug	Bolt	M35	1	32	3.2
	Carburetor joint	Bolt	M6	2	10	1.0
	Carburetor joint and carburetor	Nut	M6	2	10	1.0
	Air filter assembly	Bolt	M6	2	7	0.7
	Air filter cover	Screw	M5	5	1	0.1
	Fuel pump	Ð	M6	2	10	1.0
	Exhaust pipe assembly	Nut	M8	2	20	2.0
	Muffler	Bolt	M10	3	53	5.3
	Muffler and exhaust pipe	Bolt	M8	1	20	2.0
	Protector (Muffler)	Screw	M6	3	10	1.0
	Protector (Exhaust pipe)	Screw	M6	2	10	1.0
	Crankcase (left and right)	Bolt	M6	9	10	1.0
	Drain bolt	Bolt	M8	1	22	2.2
	Oil filler	Bolt	M14	1	3	0.3
	Transmission case cover	Bolt	M8	6	16	1.6
	Crankcase cover (left)	Bolt	M6	11	10	1.0
	Crankcase filter cover	Ð	M6	3	7	0.7
	Crankcase cover protector	Bolt	M6	2	7	0.7
	Magnet cover	Ð	M6	10	10	1.0

2-8