Checking The Ignition Timing - Yamaha YFM70RY Service Manual

5. Clean:
• Spark plug
(with a spark plug cleaner or wire brush)
6. Measure:
• Spark plug gap "a"
(with a wire thickness gauge)
Out of specification → Regap.
Spark plug gap
0.7–0.8 mm (0.028–0.031 in)
7. Install:
• Spark plug
Spark plug
13 Nm (1.3 m·kg, 9.4 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 system.
Make sure all connections are tight and free of
corrosion.
1. Connect:
• Timing light
• Digital tachometer
(to spark plug lead)
Timing light
90890-03141
Inductive clamp timing light
YU-03141
2. Check:
• Ignition timing
M MMM M MMM M M MMM M
a. Start the engine, warm it up for several min-
utes, and then let it run at the specified en-
gine idling speed.
Engine idling speed
1500–1700 r/min
b. Remove the timing mark accessing screw
"1".
c. Check that the stationary pointer "a" on the
AC magneto cover is within the firing range
"b" on the AC magneto.
Incorrect firing range → Check the ignition
system.
TIP
The ignition timing is not adjustable.
L LLL L LLL L L LLL L
3. Remove:
• Timing light
• Tachometer
4. Install:
• Timing mark accessing screw
3-9
ENGINE
M MMM M M MMM M M MMM M
b
a
L LLL L L LLL L L LLL L
MMM
1
LLL