Yamaha YZ125X1 Owner's Service Manual page 146

SPARK GAP TEST
1. Disconnect the spark plug cap
from spark plug.
2. Connect the dynamic spark tester
"1" (ignition 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,
LEADS AND IGNITION COIL
CONNECTION
1. Check:
• Couplers and leads connection
Rust/dust/looseness/short-circuit
→
Repair or replace.
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
place.
Set the tester selection position to
Ω
" × 1".
CHECKING THE IGNITION COIL
1. Inspect:
• Primary coil resistance
→
Out of specification
→
Tester (+) lead Yellow lead "1"
→
Tester (-) lead Black lead "2"
Primary Tester se-
coil resis- lector posi-
tance
Ω
0.24–0.36 at 20
°C (68 °F)
2. Inspect:
• Secondary coil resistance
→
Out of specification
→
Tester (+) lead Spark plug lead
"1"
→
Tester (-) lead Yellow lead "2"
Secondary Tester se-
coil resis- lector posi-
tance
Ω
5.7–8.5 k at 20 °C
(68 °F)
• Remove the spark plug cap by turn-
ing it counterclockwise and inspect.
• Install the spark plug cap by turning
it clockwise until it is tight.
6-3
IGNITION SYSTEM
→
→
Re-
CHECKING THE SPARK PLUG
CAP
1. Inspect:
Replace.
• Spark plug cap
Loose connection
Deteriorated/damaged
place.
• Spark plug cap resistance
Out of specification
tion
Tester (+) lead
terminal "1"
Ω
× 1
Tester (-) lead
nal "2"
Replace.
CHECKING THE CDI MAGNETO
tion
1. Inspect:
• Pickup coil resistance
Ω
k × 1
Out of specification
Tester (+) lead
"1"
Tester (-) lead
"2"
→
Tighten.
→
Re-
→
Replace.
→
Spark plug lead
→
Spark plug termi-
Spark plug Tester se-
cap resis- lector posi-
tance tion
Ω
4–6 k at
Ω
20 °C (68 k × 1
°F)
→
Replace.
→
White/Red lead
→
White/Blue lead
Tester se-
Pickup coil
lector posi-
resistance
tion
Ω
248–372
Ω
at 20 °C (68 × 100
°F)