Yamaha YFM660 01 User Manual

7 - 9
CARBCARBURETORS

Remove the carburetor.

Inspect the valve seat and needle valve.

If either is worn, replace them both.

If both are fine, adjust the float level by
bending the float tang 4
 slightly.

Install the carburetor.

Recheck the fuel level.
*********************************************** 

8 - 1
–+ELECELECTRICAL COMPONENTS
EB800000
ELECTRICAL
ELECTRICAL COMPONENTS
1Main switch 
2Front brake switch 
3Indicator light
4Circuit breaker (fan)
5Park switch
6Clutch switch
7Handlebar switch (left)
8Fuse9Starter relay
0Tail/brake light
ARectifier/regulator
BCDI unit
CBattery
DNeutral switch
EReverse switch
FSpeed sensorGRear brake switch
HIgnition coil
IHeadlight
JThermo switch 1
KFan
LThermo switch 2 
MDiode 

8 - 2
–+ELECCHECKING THE SWITCH
CHECKING THE SWITCH
CHECKING THE SWITCH
Use a pocket tester to check the terminals for
continuity. If the continuity is faulty at any
point, replace the switch.
OTE:

Set the pocket tester to “0” before starting
the test.

The pocket tester should be set to the 
“Ω ×
 1”
range when testing the switch for continuity.

Turn the switch on and off a few times when
checking it.
Pocket tester: 
P/N. YU-03112, 90890-03112
CHECKING A SWITCH SHOWN IN THE 
MANUAL
The terminal...

8 - 3
–+ELECCHECKING THE SWITCH
CHECKING THE SWITCH CONTINUITY
Refer to “CHECKING THE SWITCH” and check for continuity between lead terminals.
Poor connection, no continuity →
 Correct or replace.
* The coupler locations are circled. 

8 - 4
–+ELECCHECKING THE SWITCH
1Lights switch
2Engine stop switch
3Start switch
4Main switch
5Front brake switch
6Clutch switch
7Park switch
8Fuse
9Reverse switch
0Neutral switch
ARear brake switch  

8 - 5
–+ELECIGNITION SYSTEM
EB802000
IGNITION SYSTEM
CIRCUIT DIAGRAM
1AC magneto
3Main switch
4Battery
5Fuse
0CDI unit
AIgnition coil
BSpark plug
PEngine stop switch 

8 - 6
–+ELECIGNITION SYSTEM
EB802010
TROUBLESHOOTING
Procedure
Check:
1.Fuse
2.Battery
3.Spark plug
4.Ignition spark gap
5.Spark plug cap resistance
6.Ignition coil resistanceIF THE IGNITION SYSTEM FAILS TO OPERATE (NO SPARK OR INTERMITTENT SPARK):
7.Engine stop switch
8.Main switch
9.Pickup coil resistance 
10.Charging/rotor rotation direction detection 
coil resistance
11.Wiring connection (the entire ignition sys-
tem)
OTE:

Remove the following part(s) before trouble-
shooting:
1)Seat
2)Front fender...

8 - 7
–+ELECIGNITION SYSTEM
CORRECT
Spark plug gap:
0.8 ~ 0.9 mm (0.031 ~ 0.035 in)INCORRECT 
Repair or replace the spark plug.
For USA and CDN
4.Ignition spark gap

Disconnect the spark plug cap from the
spark plug.

Connect the dynamic spark tester 1
 as
shown.
2 Spark plug cap
3 Spark plug

Turn the main switch to “ON”.

Check the ignition spark gap.

Crank the engine by pushing the starter
switch, and increase the spark gap until a
misfiring occurs.
Minimum spark gap:
6.0 mm (0.24 in)
MEETS...

8 - 8
–+ELECIGNITION SYSTEM
5.Spark plug cap resistance

Remove the spark plug cap.

Connect the pocket tester (Ω
 ×
 1k) to the
spark plug cap.
*
MEETS
SPECIFICATION

Check that the spark plug cap has the
specified resistance.
Spark plug cap resistance:
10 kΩ at 20 °C (68 °F)
OUT OF SPECIFICATION 
Replace the spark plug cap.
6.Ignition coil resistance

Disconnect the ignition coil connector from
the wire harness.

Connect the pocket tester (Ω
 ×
 1) to the
ignition coil.
Tester (+) lead → Orange lead...

8 - 9
–+ELECIGNITION SYSTEM
BOTH MEET
SPECIFICATION

Connect the pocket tester (Ω
 ×
 1k) to the
ignition coil.
Tester (+) lead → Orange lead terminal
Tester (–) lead → Spark plug lead

Check that the secondary coil has the
specified resistance.
Secondary coil resistance:
6.32 ~ 9.48 kΩ at 20 °C (68 °F)
Replace the ignition coil.
CORRECT 7.Engine stop switch
Refer to “CHECKING THE SWITCH”.
INCORRECT
Replace the handlebar switch (left).
CORRECT 8.Main switch
Refer to “CHECKING THE SWITCH”.
INCORRECT...