Yamaha YFM660 01 User Manual

3 - 15
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...

3 - 16
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...

3 - 17
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...

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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:...

3 - 19
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...

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...

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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:...

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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...

3 - 23
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....

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...