Spark Gap Test; Checking The Couplers And Leads Connection; Checking The Engine Stop Switch; Checking The Ignition Coil - Yamaha YZ125 2009 Owner's Service Manual

SPARK GAP TEST

1. Disconnect the spark plug cap from spark
plug.
2. Connect the dynamic spark tester "1" (igni-
tion checker "2") as shown.
• Ignition coil "3"
• Spark plug "4"
A. For USA and CDN
B. Except for USA and CDN
3. Kick the kickstarter crank.
4. Check the ignition spark gap.
5. Start engine, and increase spark gap until
misfire occurs. (for USA and CDN only)
Minimum spark gap:
6.0 mm (0.24 in)
CHECKING THE COUPLERS AND LEADS
CONNECTION
1. Check:
• Couplers and leads connection
Rust/dust/looseness/short-circuit → Repair
or replace.
IGNITION SYSTEM

CHECKING THE ENGINE STOP SWITCH

1. Inspect:
• Engine stop switch conduction
Tester (+) lead → Black/White lead "1"
Tester (-) lead → Black lead "2"
Result
Conductive (while the engine stop
switch is pushed)
Not conductive while it is pushed → Replace.
Conductive while it is freed → Replace.
Set the tester selection position to "Ω × 1".

CHECKING THE IGNITION COIL

1. Inspect:
• Primary coil resistance
Out of specification → Replace.
Tester (+) lead → Yellow lead "1"
Tester (-) lead → Black lead "2"
Primary coil re-
sistance
0.24–0.36 Ω at 20
°C (68 °F)
6-5
Tester selector
position
Ω × 1