Yamaha YFM660 01 User Manual

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COOLWATER PUMP
2.Check:

Water pump seal

Oil seal 

Water pump outlet pipe
Cracks/damage/wear →
 Replace.

Bearing
Rough movement →
 Replace. 
New
ASSEMBLING THE WATER PUMP
1.Install:

Oil seal 1
 
(into the water pump housing 2
)
OTE:

Before installing the oil seal, apply tap water
or coolant onto its outer surface.

Install the oil seal with a socket 3
 that
matches its outside diameter.
2.Install:

Water pump seal 1
 
(into the water pump housing 2
)
CAUTION:
Never lubricate the water pump seal sur-
face with oil or grease.
OTE:
Install the water pump seal with the special
tools.
ÈPush down.
Mechanical seal installer 3: 
P/N. YM-33221, 90890-04078
Middle driven shaft bearing driver
4:
P/N. YM-04058-1, 90890-04058
New
New
3.Install:

Rubber damper 1
 

Rubber damper holder 2
 
OTE:
Before installing the rubber damper, apply tap
water or coolant onto its outer surface.
New
New 
						

							6 - 13
COOLWATER PUMP
4.Measure:

Impeller shaft tilt
Out of specification →
 Repeat steps (3) and
(4).
CAUTION:
Make sure that the rubber damper and rub-
ber damper holder are bottom with the
impeller.
1Straightedge
2Impeller
Max. impeller shaft tilt:
0.15 mm (0.006 in) 
						

							7 - 1
CARBCARBURETORS
CARBURETION
CARBURETORS
Order Job name/Part name Q’ty Remarks
Removing the carburetors
Remove the parts in the order below.
Seat/front fender/fuel tank/rubber cover 
2Refer to “SEAT, FENDERS AND FUEL 
TANK” in CHAPTER 3.
1 Air vent hose 2
2 Float chamber breather hose 1
3 Starter cable/starter plunger 1/1
4 Throttle valve cover 1
5 Throttle cable end 1
6 Throttle cable 1
7 Clamp screw (air filter case) 2 Loosen.
8 Clamp screw (carburetor joint) 2 Loosen.
9 Carburetors 1
For installation, reverse the removal pro-
cedure. 
						

							7 - 2
CARBCARBURETORS
Order Job name/Part name Q’ty Remarks
Separating the carburetors
Remove the parts in the order below.
1 Drain hose 2
2 Plate 1
3 Connecting bolt/spacer 2/2
4Spring 1
5Hose joint 1
6Pipe 1
7 Carburetor 2 1
8 Carburetor 1 1
For installation, reverse the separating
procedure. 
						

							7 - 3
CARBCARBURETORS
Order Job name/Part name Q’ty Remarks
Disassembling the carburetor
Remove the parts in the order below.
1
  Throttle stop screw 1
2
  Vacuum chamber cover 1
3
 Spring 1
4
  Jet needle holder 1
5
 Spring 1
6
  Jet needle set 1
7
 Piston valve 1
8
 Float chamber 1
9
 Drain screw  1
0
  Float 1 Refer to “ASSEMBLING THE CARBURE-
TOR”.
A
 Needle valve set 1 
						

							7 - 4
CARBCARBURETORS
Order Job name/Part name Q’ty Remarks
B
 Pilot jet 1
C
  Pilot screw set 1 Refer to “DISASSEMBLING/
ASSEMBLING THE CARBURETOR”.
OTE:
Before disassembling the carburetor,
make sure to note the number of times
the pilot screw is turned out from the
seated position to its set position.
D
 Main jet 1
E
  Needle jet 1 Refer to “ASSEMBLING THE CARBURE-
TOR”.
F
 Starter jet 1
G
 Pilot air jet 1
For assembly, reverse the disassembly
procedure. 
						

							7 - 5
CARBCARBURETORS
DISASSEMBLING THE CARBURETOR
OTE:
Before disassembling the carburetor, make
sure to note the number of times the pilot
screw is turned out from the seated position to
its set position.
CHECKING THE CARBURETOR
1.Check:

Carburetor body

Float chamber
Cracks/damage →
 Replace.

Fuel passage
Contamination →
 Clean as indicated.

Fuel chamber body 
Contamination →
 Clean.
***********************************************
Cleaning steps:

Wash the carburetor in a petroleum based
solvent.
(Do not use any caustic carburetor cleaning
solution.)

Blow out all of the passages and jets with
compressed air.
***********************************************
2.Check:

Float 1
 

Float tang 2
 
Damage →
 Replace.
3.Check:

Valve seat 1
 

Needle valve 2
 

O-ring 3
 
Contamination/wear/damage →
 Replace as
a set.
OTE:
Always replace the needle valve and valve
seat as a set. 
						

							7 - 6
CARBCARBURETORS
4.Check:

Piston valve 1
 
Scratches/wear/damage →
 Replace.

Rubber diaphragm 2
 
Tears →
 Replace.
5.Check:

Vacuum chamber cover 1
 

Spring 2
 
Cracks/damage →
 Replace.
6.Check:

Jet needle 1
 

Main jet 2
 

Needle jet 3
 

Pilot air jet 4
 

Pilot jet 5
 

Pilot screw 6
 

Starter jet 7
 

Starter plunger 8
 
Bends/wear/damage →
 Replace.

Blockage →
 Blow out the jets with
compressed air.
7.Check:

Free movement (piston valve)
Sticks →
 Replace the piston valve guide and
the piston valve.
Insert the piston valve into the carburetor
body, and check for free movement.
8.Check:

Free movement (throttle valve)
Sticks →
 Replace. 
						

							7 - 7
CARBCARBURETORS
ASSEMBLING THE CARBURETOR
CAUTION:
Before reassembling, wash all of the parts
in a clean petroleum based solvent.
1.Install:

Pilot screw 1
 
OTE:
Before assembling the carburetor, make sure
to turn out the pilot screw the same number of
times, as noted before disassembly, from the
seated position to the set position.
2.Measure:

Float height a
 
Out of specification →
 Adjust.
***********************************************
Measurement and adjustment steps:

Hold the carburetor in an upside down
position.

Measure the distance from the front mating
surface of the float chamber (gasket
removed) to the top of the float.
OTE:
The float arm should be resting on the needle
valve, but not compressing it.

If the float height is not within the
specification, inspect the valve seat and
needle valve.

If either is worn, replace them both.

If both are fine, adjust the float height by
bending the float tang 1
 on the float.

Recheck the float height.
***********************************************
Float height (F.H.):
13 mm (0.51 in) 
						

							7 - 8
CARBCARBURETORS
3.Install:

Carburetor 1

Carburetor 2

Pipe

Hose joint

Spring
OTE:

Install the throttle valve lever 1
 onto
carburetor 2 between the spring 2
 and
synchronizing screw 3
.

Make sure the throttle valves operate
smoothly and that the synchronization is
correct.
ADJUSTING THE FUEL LEVEL
1.Measure:

Fuel level a
 
Out of specification →
 Adjust. 
Fuel level:
3 ~ 4 mm (0.12 ~ 0.16 in)
Below the float chamber mating
surface
***********************************************
Fuel level measurement and adjustment 
steps:

Place the machine on a level surface.

Connect the fuel level gauge 1
 to the drain
pipe 2
. 

Loosen the drain screw 3
.

Hold the gauge vertically next to the float
chamber line.

Measure the fuel level a
 with the gauge.

If the fuel level is incorrect, adjust the fuel
level.
Fuel level gauge:
P/N. YM-01312-A, 90890-01312