Yamaha YFM660 01 User Manual

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CHK
ADJ
ADJUSTING THE STARTER CABLE
ADJUSTING THE STARTER CABLE
1.Adjust:

Starter cable
***********************************************
Adjustment steps:

Disconnect the starter cable 1
 from the car-
buretor body.
NOTE:
Do not remove the starter plunger 2
 from the
starter cable.

Measure the starter plunger stroke distance
a
 of the starter lever 3
 fully close-to-fully
open position.
If the distance is out of specification adjust it
as described below.
È
Fully closed position
É
Fully open position

Pull back the boot 4
.

Loosen the locknut 5
.

Turn the adjuster 6
 in or out until the correct
distance is obtained.

Tighten the locknut 5
.

Push in the boot 4
.

Connect the starter cable.
WARNING
After adjusting the cable, turn the handle-
bar to right to left, and make sure that the
engine idling speed does not increase.
***********************************************
Starter plunger stroke distance a:
15 mm (0.59 in)
Turning in Distance increased.
Turning out Distance decreased. 
						

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CHK
ADJ
CHECKING THE SPARK PLUG
1.Remove:

Spark plug
2.Check:

Spark plug type
Incorrect →
 Replace.
Standard spark plug:
DPR8EA-9/NGK
3.Check:

Electrode 1
 
Wear/damage →
 Replace.

Insulator 2
 
Abnormal color →
 Replace.
Normal color is a medium-to-light tan color.
4.Clean the spark plug with a spark plug
cleaner or wire brush.
5.Measure:

Plug gap a
 
Use a wire gauge or feeler gauge.
Out of specification →
 Regap.
6.Tighten:

Spark plug
NOTE:
Before installing a spark plug, clean the gasket
surface and plug surface.
Spark plug gap:
0.8 ~ 0.9 mm (0.031 ~ 0.035 in)
T R..18 Nm (1.8 m  kg, 13 ft  lb)
CHECKING THE SPARK PLUG 
						

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CHK
ADJ
CHECKING THE IGNITION TIMING
CHECKING THE IGNITION TIMING
NOTE:
Engine idling speed and throttle cable free play
should be adjusted properly before checking
the ignition timing.
1.Attach:

Tachometer

Timing light
(to spark plug lead)
Timing light:
P/N. YM-33277-A, 90890-03141
2.Check:

Ignition timing
***********************************************
Checking steps:

Warm up the engine and keep it at the speci-
fied speed.

Remove the timing mark accessing screw 1
.

Visually check the stationary pointer 2
 to
verify it is within the required firing range 3
indicated on the flywheel.
Incorrect firing range →
 Check the pulser coil
assembly.

Install the timing mark accessing screw.
***********************************************
3.Detach:

Timing light

Tachometer
Engine speed:
1,450 ~ 1,550 r/min 
						

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CHK
ADJ
MEASURING THE COMPRESSION PRESSURE
MEASURING THE COMPRESSION 
PRESSURE
NOTE:
Insufficient compression pressure will result in
a loss of performance.
1.Check:

Valve clearance
Out of specification →
 Adjust.
Refer to “ADJUSTING THE VALVE CLEAR-
ANCE”.
2.Start the engine and let it warm up for sev-
eral minutes.
3.Stop the engine.
4.Remove:

Spark plug
5.Attach:

Adapter

Compression gauge 1
 
Compression gauge:
P/N. YU-33223, 90890-03081
Adapter:
P/N. YU-33223-3, 90890-04082
6.Measure:

Compression pressure
Above the maximum pressure:
Inspect the cylinder head, valve surfaces,
and piston crown for carbon deposits.
Below the minimum pressure:
Squirt a few drops of oil into the affected cyl-
inder and measure again.

Refer to the table below.
Compression pressure
(with oil introduced into cylinder)
Reading Diagnosis
Higher than 
without oilWorn or damaged piston, 
rings or cylinder wall.
Same as 
without oilDefective valves or 
cylinder head gasket. 
						

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CHK
ADJMEASURING THE COMPRESSION PRESSURE/
CHECKING THE ENGINE OIL LEVEL
***********************************************
Measurement steps:

Crank over the engine with the electric
starter (be sure the battery is fully charged)
with the throttle fully-open until the compres-
sion reading on the gauge stabilizes.
WARNING
When cranking the engine, ground the
spark plug lead to prevent sparking.
***********************************************
7.Install:

Spark plugCompression pressure (at sea level):
Standard:
1,250 kPa (12.5 kg/cm
2, 181 psi)
Minimum:
1,050 kPa (10.5 kg/cm
2, 149 psi)
Maximum:
1,350 kPa (13.5 kg/cm
2, 192 psi)
T R..18 Nm (1.8 m  kg, 13 ft  lb)
CHECKING THE ENGINE OIL LEVEL
1.Place the machine on a level surface.
2.Start the engine, warm it up until the engine
oil has reached a normal temperature of
60 °C (140 °F), let it continue to idle for ten
seconds, and then turn the engine off.
NOTE:
To achieve the proper engine oil temperature
for an accurate oil level reading, the engine
must have first completely cooled down, and
then warmed up again for several minutes to
normal operating temperature. 
						

							3 - 20
CHK
ADJCHECKING THE ENGINE OIL LEVEL/
CHANGING THE ENGINE OIL
3.Check:

Engine oil level
Oil level should be between the minimum
level mark a
 and the maximum level mark
b
.
Low oil level →
 Add oil to the proper level.
NOTE:

Wait a few minutes until the oil settles before
inspecting the oil level.

Do not screw the dipstick 1
 in when inspect-
ing the oil level.
NOTE:
Recommended oil classification:
API Service “SE”, “SF”, “SG” type or equiva-
lent (e.g. “SF–SE–CC”, “SF–SE–SD” etc.)
CAUTION:

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.
4.Start the engine and let it warm up for sev-
eral minutes.
5.Stop the engine and inspect the oil level
again.
NOTE:
Wait a few minutes until the oil settles before
inspecting the oil level.
Recommended oil:
Follow the left chart.
CHANGING THE ENGINE OIL
1.Remove:

Engine skid plate
Refer to “SEAT, FENDERS AND FUEL
TANK”.
2.Start the engine and let it warm up for sev-
eral minutes.
3.Stop the engine and place a container under
the engine oil drain bolt. 
						

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CHK
ADJ
CHANGING THE ENGINE OIL
4.Remove:

Dipstick 1
 

Engine oil drain bolt (oil tank) 2
 

Engine oil drain bolt (crankcase) 3
 
Drain the engine oil from the oil tank and
crankcase.
5.If the oil filter cartridge is also to be replaced,
perform the following procedure.
***********************************************
Replacement steps:

Remove the oil filter cartridge 1
 with an oil
filter wrench 2
.

Apply a thin coat of engine oil to the O-ring
3
 of the new oil filter cartridge.
CAUTION:
Make sure that the O-ring 3 is properly
seated in the groove of the oil filter car-
tridge.
Oil filter wrench:
P/N. YM-01469, 90890-01469 
						

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CHK
ADJ
CHANGING THE ENGINE OIL

Tighten the new oil filter cartridge to specifi-
cation with an oil filter wrench.
***********************************************
6.Install:

Engine oil drain bolt (crankcase)

Engine oil drain bolt (oil tank)
7.Fill:

Oil tank
(with the specified amount of the recom-
mended engine oil)
NOTE:

Pour the engine oil in several stages.

First, pour in 1.75 L (1.54 Imp qt, 1.85 US qt)
of oil, and then start the engine and rev it 3 to
5 times. Stop the engine, and then pour in
the remainder of the specified amount.
CAUTION:
When starting the engine make sure the
dipstick is securely fitted into the oil tank.
8.Install:

Dipstick
9.Warm up the engine for a few minutes, then
stop the engine.
10.Check:

Engine
(for engine oil leaks)

Oil level
Refer to “CHECKING THE ENGINE OIL
LEVEL”.
T R..
Oil filter cartridge:
17 Nm (1.7 m  kg, 12 ft  lb)
Quantity:
Total amount:
2.3 L (2.02 Imp qt, 2.43 US qt)
Periodic oil replacement:
1.9 L (1.67 Imp qt, 2.01 US qt)
With oil filter cartridge replace-
ment:
1.95 L (1.72 Imp qt, 2.06 US qt)
T R..30 Nm (3.0 m  kg, 22 ft  lb)
T R..25 Nm (2.5 m  kg, 18 ft  lb) 
						

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CHK
ADJCHANGING THE ENGINE OIL/
ADJUSTING THE CLUTCH CABLE
11.Check:

Engine oil pressure
***********************************************

Slightly loosen the oil gallery bolt 1
.

Start the engine and keep it idling until
engine oil starts to seep from the oil gallery
bolt. If no engine oil comes out after one
minute, turn the engine off so that it will not
seize.

Check the engine oil passages, the oil filter
cartridge and the oil pump for damage or
leakage. 
Refer to “OIL PUMP” in CHAPTER 5.

Start the engine after solving the problem(s)
and check the engine oil pressure again.

Tighten the oil gallery bolt to specification.
***********************************************
12.Install:

Engine skid plate
Refer to “SEAT, FENDERS AND FUEL
TANK”.
T R..
Oil gallery bolt:
7 Nm (0.7 m  kg, 5.1 ft  lb)
ADJUSTING THE CLUTCH CABLE
1.Check:

Clutch lever free play a
 
Out of specification →
 Adjust.
Clutch lever free play
(at the clutch lever end):
5 ~ 10 mm (0.20 ~ 0.39 in) 
						

							3 - 24
CHK
ADJADJUSTING THE CLUTCH CABLE/
CLEANING THE AIR FILTER
2.Adjust:

Clutch lever free play
***********************************************
Adjustment steps:

Pull the rubber cover 1
 off.

Loosen the locknut 2
 and finger tighten the
adjusting bolt 3
.

Loosen the locknut 4
.

Turn the adjusting nut 5
 until the clutch lever
free play is within the specified limits.

Tighten the locknut 4
.
NOTE:
If the specified clutch lever free play cannot be
obtained on it, use the adjusting bolt 3
.

Turn the adjusting bolt 3
 until the clutch
lever free play is within the specified limits.

Tighten the locknut 2
.

Pull the rubber cover 1
 in.
***********************************************
Clutch lever free play
(at the clutch lever end):
5 ~ 10 mm (0.20 ~ 0.39 in)
CLEANING THE AIR FILTER
NOTE:
There is a check hose 1
 at the bottom of the
air filter case. If dust and/or water collects in
this hose, clean the air filter element and air fil-
ter case.
1.Remove:

Seat
Refer to “SEAT, FENDERS AND FUEL
TANK”.
2.Disconnect:

Crankcase breather hose 1
 
3.Remove:

Air filter case cover 2