Yamaha YZ250F(X) Owner's Service Manual page 174

SPARK GAP TEST
1. Disconnect the ignition coil from
spark plug.
2. Remove the ignition coil cap.
3. 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
4. Kick the kickstarter crank.
5. Check the ignition spark gap.
6. 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.
• Ignition coil and spark plug as
they are fitted
Push in the ignition coil until it
closely contacts the spark plug
hole in the cylinder head cover.
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. Remove the ignition coil cap.
2. Inspect:
• Primary coil resistance
→
Out of specification
→
Tester (+) lead Orange lead "1"
→
Tester (-) lead Black lead "2"
Primary Tester se-
coil resis- lector posi-
tance
0.08–0.10
Ω
at 20 °C
(68 °F)
3. Inspect:
• Secondary coil resistance
→
Out of specification
→
Tester (+) lead Orange lead "1"
→
Tester (-) lead Spark plug termi-
nal "2"
Secondary Tester se-
coil resis- lector posi-
tance
4.6–6.8
Ω
k at 20 °C
(68 °F)
6-3
IGNITION SYSTEM
→
→
Re-
4. Inspect:
• Sealed portion of ignition coil "a"
• Spark plug terminal pin "b"
• Threaded portion of spark plug "c"
Wear
CHECKING THE CDI MAGNETO
1. Inspect:
• Pickup coil resistance
Out of specification
Replace.
Tester (+) lead
Tester (-) lead
tion
Ω
× 1
2. Inspect:
• Charging coil 1 resistance
Out of specification
Replace.
Tester (+) lead
Tester (-) lead
tion
Ω
k × 1
→
Replace.
→
Replace.
→
Red lead "1"
→
White lead "2"
Tester se-
Pickup coil
lector posi-
resistance
tion
Ω
248-372
Ω
at 20 °C (68 ×100
°F)
→
Replace.
→
Brown lead "1"
→
Green lead "2"
Charging Tester se-
coil 1 resis- lector posi-
tance tion
720-1,080
Ω Ω
at 20 °C ×100
(68 °F)