2003 YAMAHA TTR90 ignition

–+ELEC
6 - 2
IGNITION SYSTEM
EC620000
IGNITION SYSTEM
INSPECTION STEPS
Use the following steps for checking the possibility of the malfunctioning engine being attributable to
ignition system failure and for checking the spark plug which will not spark.
NOTE:
Remove the following parts before inspection.
1) Seat
2) Fuel tank
Use the following special tools in this inspection.
Spark gap testClean or replace
spark plug.
Check entire ignition
system for connection.Repair or replace.
Check “ENGINE STOP”
switch.Replace.
Check ignition coil. Primary coil Replace.
Secondary coil Replace.
Check CDI magneto. Pickup coil Replace.
Source coil Replace.
Replace CDI unit.
Dynamic spark tester:
YM-34487
Ignition checker:
90890-06754Pocket tester:
YU-3112-C/90890-03112
No Spark
OK
OK
OK
OK
Spark
No good
No good
No good
No good
No good
No good

6 - 3
–+ELECIGNITION SYSTEM
EC622001
SPARK GAP TEST
1. Disconnect the spark plug cap from spark
plug.
2. Connect the dynamic spark tester 1
(ignition checker 2) as shown.
Spark plug cap 3
Spark plug 4
ÅFor USA and CDN
ıExcept for USA and CDN
3. Kick the kick starter.
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)
Å
ı
EC624000
COUPLERS AND LEADS CONNECTION
INSPECTION
1. Check:
Couplers and leads connection
Rust/dust/looseness/short-circuit →
Repair or replace.
“ENGINE STOP” SWITCH INSPECTION
1. Inspect:
“ENGINE STOP” switch continuity
No continuous while being pushed “” →
Replace.
Continuous while being pushed “” →
Replace.Tester (+) lead → Black/White lead 1
Tester (–) lead → Black lead 2
B/W
1B
2Tester selec-
tor position
Ω × 1

6 - 4
–+ELECIGNITION SYSTEM
EC626002
IGNITION COIL INSPECTION
1. Inspect:
Primary coil resistance
Out of specification → Replace.
Tester (+) lead → Orange lead 1
Tester (–) lead → Black lead 2
Primary coil
resistanceTester selector
position
0.18 ~ 0.28 Ω at
20 ˚C (68 ˚F)Ω × 1
2. Inspect:
Secondary coil resistance
Out of specification → Replace.
NOTE:
When inspecting the secondary coil resis-
tance, remove the spark plug cap.
CDI MAGNETO INSPECTION
1. Inspect:
Pickup coil resistance
Out of specification → Replace. Tester (+) lead → Spark plug lead 1
Tester (–) lead → Orange lead 2
Secondary coil
resistanceTester selector
position
6.3 ~ 9.5 kΩ at
20 ˚C (68 ˚F)kΩ × 1
Tester (+) lead → Red lead 1
Tester (–) lead → White lead 2
Pickup coil
resistanceTester selector
position
248 ~ 372 Ω at
20 ˚C (68 ˚F)Ω × 100

6 - 5
–+ELECIGNITION SYSTEM
2. Inspect:
Source coil resistance
Out of specification → Replace.
Tester (+) lead → Brown lead 1
Tester (–) lead → Green lead 2
Source coil
resistanceTester selector
position
688 ~ 1,032 Ω
at 20 ˚C (68 ˚F)Ω × 100

6 - 7
–+ELECCARBURETOR HEATING SYSTEM
EC624000
COUPLERS AND LEADS CONNECTION
INSPECTION
1. Check:
Couplers and leads connection
Rust/dust/looseness/short-circuit →
Repair or replace.
CDI MAGNETO INSPECTION
1. Inspect:
Source coil resistance
Refer to “IGNITION SYSTEM” section.
THERMO SWITCH INSPECTION
1. Inspect:
Thermo switch operation
Faulty operation → Replace.
Inspection steps:
Remove the thermo switch.
Connect the pocket tester to the thermo
switch coupler as shown.
Tester (+) lead → Black 1
Tester (–) lead → Black 2
Immerse the thermo switch in a container
filled with water 3.
Place a thermometer 4 in the water.
Slowly heat the water, and then let it cool to
the specified temperature as indicated in
the table.
Check the thermo switch for continuity at
the temperatures indicated in the table.