Yamaha YFM660 01 User Manual

GEN 
INFO
1
SPEC2
CHK 
ADJ
3
CHAS4
ENG5
COOL6
CARB7
ELEC8
TRBL
SHTG
9
–+
CLUTCH ...................................................................................................... 5-43
REMOVING THE CLUTCH  ................................................................. 5-47
REMOVING THE PRIMARY DRIVE GEAR 
AND BALANCER DRIVEN GEAR  ................................................... 5-47
CHECKING THE FRICTION PLATE  ................................................... 5-48
CHECKING THE CLUTCH PLATE...

TRANSMISSION ......................................................................................... 5-72
MAIN AXLE  ......................................................................................... 5-74
DRIVE AXLE  ....................................................................................... 5-75
CHECKING THE SHIFT FORK  ........................................................... 5-77
CHECKING THE SHIFT DRUM  .......................................................... 5-77
CHECKING...

GEN 
INFO
1
SPEC2
CHK 
ADJ
3
CHAS4
ENG5
COOL6
CARB7
ELEC8
TRBL
SHTG
9
–+
CHAPTER 8.
ELECTRICAL
ELECTRICAL COMPONENTS ..................................................................... 8-1
CHECKING THE SWITCH ............................................................................ 8-2
CHECKING THE SWITCH  .................................................................... 8-2
CHECKING A SWITCH SHOWN IN THE MANUAL  ............................. 8-2
CHECKING THE SWITCH CONTINUITY...

CHAPTER 9.
TROUBLESHOOTING
STARTING FAILURE/HARD STARTING ..................................................... 9-1
FUEL SYSTEM ...................................................................................... 9-1
ELECTRICAL SYSTEM ......................................................................... 9-1
COMPRESSION SYSTEM  .................................................................... 9-2
POOR IDLE SPEED PERFORMANCE ........................................................ 9-2
POOR IDLE...

1 - 1
GEN
INFO
MACHINE IDENTIFICATION
GENERAL INFORMATION
MACHINE IDENTIFICATION
VEHICLE IDENTIFICATION NUMBER
The vehicle identification number 1
 is
stamped into the left side of the frame.
MODEL LABEL
The model label 1
 is affixed to the air filter
case cover. This information will be needed to
order spare parts. 

1 - 2
GEN
INFO
EB101000
IMPORTANT INFORMATION
PREPARATION FOR REMOVAL 
PROCEDURES
1.Remove all dirt, mud, dust and foreign mate-
rial before removal and disassembly.
2.Use proper tools and cleaning equipment.
Refer to the “SPECIAL TOOLS” section.
3.When disassembling the machine, always
keep mated parts together. This includes
gears, cylinder, piston and other parts that
have been “mated” through normal wear.
Mated parts must always be reused or
replaced as an assembly.
4.During machine disassembly,...

1 - 3
GEN
INFO
EB101030
LOCK WASHERS/PLATES AND COTTER 
PINS
1.Replace all lock washers/plates 1
 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
1.Install bearings and oil seals so that the
manufacturer’s marks or numbers are visible.
When installing oil seals, apply a light coat-
ing of lightweight lithium base grease to the
seal lips. Oil bearings liberally when install-
ing, if...

1 - 4
GEN
INFO
CHECKING OF CONNECTIONS
EB801000
CHECKING OF CONNECTIONS
Check the connectors for stains, rust, mois-
ture, etc.
1.Disconnect:

Connector
2.Check:

Connector 
Moisture →
 Dry each terminal with an air
blower. 
Stains/rust →
 Connect and disconnect the
terminals several times.
3.Check:

Connector leads 
Looseness →
 Bend up the pin 1
 and con-
nect the terminals.
4.Connect:

Connector terminals
NOTE:
The two terminals “click” together.
5.Check:

Continuity (using a pocket tester)
NOTE:

If...

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GEN
INFO
SPECIAL TOOLS
EB102001
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. Special tools may differ by shape and part number from country to
country. In such a case, two types are provided.
When placing an order, refer to the list provided below to avoid any mistakes.
For US and CDN
P/N. YM-, YU-, YS-,...

1 - 6
GEN
INFO
SPECIAL TOOLS
90890-01304
YU-01304Piston pin puller
This tool is used to remove the piston pin.
90890-01311
YM-08035Tappet adjusting tool (3 mm)
This tool is necessary for adjusting the 
valve clearance.
90890-01312
YM-01312-AFuel level gauge
This gauge is used to measure the fuel 
level in the float chamber.
90890-01325
YU-24460-01Radiator cap tester
This tool is used to check the cooling sys-
tem.
90890-01352
YU-33984Adapter
This tool is used to check the cooling sys-
tem.
90890-01327...