Yamaha YZF-R125 Service Manual: Starting circuit cut-off system operation
If the engine stop switch is set to "
" and the main switch is set to
"ON" (both switches are closed), the
starter motor can only operate if at least one of the following conditions is
met:
- The transmission is in neutral (the neutral switch is closed).
- The clutch lever is pulled to the handlebar (the clutch switch is closed) and the sidestand is up (the sidestand switch is closed).
The starting circuit cut-off relay prevents the starter motor from operating
when neither of these conditions
has been met. In this instance, the starting circuit cut-off relay is open so
current cannot reach the
starter motor. When at least one of the above conditions has been met, the
starting circuit cut-off relay
is closed and the engine can be started by pressing the start switch "
".
a. WHEN THE TRANSMISSION IS IN NEUTRAL
b. WHEN CLUTCH LEVER IS PULLED TO THE HANDLEBAR AND THE SIDESTAND IS UP
1. Battery
2. Main fuse
3. Main switch
4. Ignition fuse
5. Engine stop switch
6. Starting circuit cut-off relay
7. Clutch switch
8. Sidestand switch
9. Diode
10.Neutral switch
11.Start switch
12.Starter relay
13.Starter motor
Circuit diagram
4. Main fuse
5. Main switch
7. Clutch switch
8. Sidestand switch
9. Battery
10.Starter relay
11.Starter motor
12.Starting circuit cut-off relay
13.Diode
14.Neutral switch
16.Start switch ...
Troubleshooting
The starter motor fails to turn.
NOTE:
Before troubleshooting, remove the following part(s):
1. Seats
2. Fuel tank
3. Left lower side cowling
4. Left upper side cowling
...
Other materials:
Checking the crankshaft
1. Measure:
Crankshaft runout
Out of specification Replace
the crankshaft,
bearing or both.
NOTE:
Turn the crankshaft slowly.
2. Measure:
Big end side clearance
Out of specification Replace
the crankshaft.
3. Measure:
Crankshaft width
Out of specification&nbs ...
Installing the primary drive gear and balancer gears
1. Install:
Balancer driven gear "1"
Lock washer
Balancer drive gear "2"
Primary drive gear
Washer "3"
Balancer driven gear nut
Primary drive gear nut
NOTE:
Align the punch mark "a" in the balancer drive
gear "2" with the punch mark "b" in the balancer
driven gear "1".
...
Starting failures
Engine
1. Cylinder and cylinder head
- Loose spark plug
- Loose cylinder head or cylinder
- Damaged cylinder head gasket
- Damaged cylinder gasket
- Worn or damaged cylinder
- Incorrect valve clearance
- Improperly sealed valve
- Incorrect valve-to-valve-seat contact
- Incorrect valve timi ...