Checking The Ignition Timing; Measuring The Compression Pressure - Yamaha 2009 YFM25RY Service Manual

7. Install:
• Spark plug
Spark plug
18 Nm (1.8 m·kg, 13 ft·lb)
TIP
Before installing the spark plug, clean the
spark plug and gasket surface.
8. Connect:
• Spark plug cap
EAS20700

CHECKING THE IGNITION TIMING

TIP
Prior to checking the ignition timing, check the
wiring connections of the entire ignition sys-
tem. Make sure all connections are tight and
free of corrosion.
1. Connect:
• Timing light
• Digital tachometer
(onto the ignition coil spark plug lead)
Timing light
90890-03141
Inductive clamp timing light
YU-03141
Digital tachometer
90890-06760
YU-39951-B
2. Check:
• Ignition timing
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Start the engine, warm it up for several
minutes, and then let it run at the specified
engine idling speed.
Engine idling speed
1500–1600 r/min
b. Remove the timing mark accessing screw
"1".
c. Check that the stationary pointer "a" is
within the firing range "b" on the pickup coil
rotor.
Incorrect firing range → Check the ignition
system.
d. Install the timing mark accessing screw.
TIP
The ignition timing is not adjustable.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
3. Detach:
• Timing light
• Digital tachometer
EAS20710
MEASURING THE COMPRESSION PRES-
SURE
The following procedure applies to the cylinder.
TIP
Insufficient compression pressure will result in
a loss of performance.
1. Measure:
• Valve clearance
Out of specification → Adjust.
Refer to "ADJUSTING THE VALVE
CLEARANCE" on page 3-4.
2. Start the engine, warm it up for several
minutes, and then turn it off.
3. Disconnect:
• Spark plug cap
3-8
ENGINE