Spark Gap Test; Checking The Engine Stop Switch; Checking The Ignition Coil; Checking The Couplers, Leads And Ignition Coil Connection - Yamaha YZ250F(D) Owner's Service Manual

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 → Re-
place.
Set the tester selection position to "Ω
× 1".
B B /W

CHECKING THE IGNITION COIL

1. Remove the ignition coil cap.
2. Inspect:
• Primary coil resistance
Out of specification → Replace.
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)
6-4
IGNITION SYSTEM
3. Inspect:
• Secondary coil resistance
Out of specification → Replace.
Tester (+) lead → Orange lead "1"
Tester (-) lead → Spark plug termi-
nal "2"
4. Inspect:
• Sealed portion of ignition coil "a"
• Spark plug terminal pin "b"
• Threaded portion of spark plug "c"
Wear → Replace.
CHECKING THE CDI MAGNETO
1. Inspect:
• Pickup coil resistance
Out of specification → Replace.
tion
Tester (+) lead → Red lead "1"
Tester (-) lead → White lead "2"
Ω × 1
Pickup coil
at 20 °C (68
Secondary Tester se-
coil resis- lector posi-
tance tion
4.56–6.84
kΩat 20 °C kΩ × 1
(68 °F)
Tester se-
lector posi-
resistance
tion
248–372 Ω
Ω ×100
°F)
W Br P
R G B