2000 YAMAHA TTR125 check engine

3 - 25
INSP
ADJ
ELECTRICAL/SPARK PLUG INSPECTION
EC370000
ELECTRICAL
EC371001
SPARK PLUG INSPECTION
1. Remove:
lSpark plug
2. Inspect:
lElectrode 1
Wear/damage ® Replace.
lInsulator color 2
Normal condition is a medium to light
tan color.
Distinctly different color ® Check the
engine condition.
NOTE:
When the engine runs for many hours at low
speeds, the spark plug insulator will become
sooty, even if the engine and carburetor are in
good operating condition.
3. Measure:
lPlug gap a
Use a wire gauge or thickness gauge.
Out of specification ® Regap.
4. Clean the plug with a spark plug cleaner
if necessary.
Spark plug gap:
0.6 ~ 0.7 mm (0.02 ~ 0.03 in)
Standard spark plug:
CR7HSA (NGK)
U22FSR-U (DENSO)
5. Tighten:
lSpark plug
NOTE:
lBefore installing a spark plug, clean the gas-
ket surface and plug surface.
lFinger-tighten a the spark plug before
torquing to specification b.
T R..13 Nm (1.3 m · kg, 9.4 ft · lb)

4 - 19
ENGCYLINDER HEAD
9. Check:
lValve clearance
Out of specification ® Adjust.
Refer to “VALVE CLEARANCE
INSPECTION AND ADJUSTMENT”
section in CHAPTER 3.
10. Apply:
lEngine oil
To camshaft.
11. Install:
lTappet cover 1
lCylinder head side cover 2
T R..18 Nm (1.8 m · kg, 13 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
12. Install:
lTiming mark accessing screw 1
lCrankshaft end accessing screw 2
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
13. Install:
lSpark plug
lEngine bracket
T R..13 Nm (1.3 m · kg, 9.4 ft · lb)
T R..40 Nm (4.0 m · kg, 29 ft · lb)

4 - 47
ENGCLUTCH AND PRIMARY DRIVEN GEAR
5. Install:
lBall
NOTE:
Apply the engine oil on the ball.
6. Install:
lPush rod 1 1
lPush plate 2
lWasher 3
lNut (push rod 1) 4
7. Install:
lPressure plate 1
lClutch spring 2
lBolt (clutch spring) 3
NOTE:
lAlign the arrow mark a on the pressure
plate with the punched mark b on the clutch
boss.
lTighten the bolts in stage, using a crisscross
pattern.
T R..6 Nm (0.6 m · kg, 4.3 ft · lb)
8. Check:
lPush lever position
Push the push lever assembly in the
arrow direction and make sure that the
mach mark are aligned ® adjust.
aMatch mark on the push lever assembly
bMatch mark on the crankcase

4 - 67
ENGCRANKCASE, CRANKSHAFT AND BALANCER
REMOVAL POINTS
Crankcase
1. Remove:
lBolt (crankcase)
lLead guide 1
lClutch cable holder 2
NOTE:
Loosen each bolt 1/4 of a turn at a time and
after all the bolts are loosened, remove them.
2. Remove:
lRight crankcase 1
Use the crankcase separating tool 2.
NOTE:
lFully tighten the tool holding bolts, but make
sure the tool body is parallel with the case. If
necessary, one screw may be backed out
slightly to level tool body.
lAs pressure is applied, alternately tap on the
front engine mounting boss and transmission
shafts.
CAUTION:
Use soft hammer to tap on the case half.
Tap only on reinforced portions of case. Do
not tap on gasket mating surface. Work
slowly and carefully. Make sure the case
halves separate evenly. If one end “hangs
up”, take pressure off the push screw, re-
align, and start over. If the cases do not
separate, check for a remaining case screw
or fitting. Do not force.
Crankcase separating tool:
YU-01135-A/90890-01135

4 - 78
ENGTRANSMISSION, SHIFT CAM AND SHIFT FORK
Shift cam and shift fork
1. Install:
lShift fork 1 (L) 1
lShift fork 2 (C) 2
lShift fork 3 (R) 3
NOTE:
lMesh the shift fork #1 (L) with the 2nd wheel
gear and #3 (R) with the 4th wheel gear on
the drive axle.
lMesh the shift fork #2 (C) with the 3rd pinion
gear on the main axle.
2. Install:
lShift cam 1
NOTE:
Apply the engine oil on the shift cam.
3. Install:
lShift fork guide bar 1 (short) 1
lShift fork guide bar 2 (long) 2
NOTE:
lApply the engine oil on the guide bars.
lBe sure the long bar is inserted into the shift
forks #1 and #3 and the short one into #2.
4. Check:
lShifter operation
lTransmission operation
Unsmooth operation ® Repair.

6 - 2
–+ELEC

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.
*marked: Only when the ignition checker is used.
NOTE:

l
Remove the following parts before inspection.
1) Seat
2) Fuel tank
l
Use the following special tools in this inspection.
Spark gap test*Clean 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 coilReplace.
Check CDI magneto. Pickup coil Replace.
Charging coil Replace.
Replace CDI unit.
Dynamic spark tester:
YM-34487
Ignition checker:
90890-06754
Pocket tester:
YU-03112/90890-03112
No Spark
OK
OK
OK
OK
Spark
No good
No good
No good
No good
No good
No good

6 - 3
–+ELEC

IGNITION SYSTEM
SPARK GAP TEST
1. Disconnect the spark plug cap from spark
plug.
2. Connect the dynamic spark tester
1
(ignition checker
2
) as shown.
l
Spark plug cap
3

l
Spark plug
4


For USA and CDN
õ
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)

õ

EC624000
COUPLERS AND LEADS CONNECTION
INSPECTION
1. Check:
l
Couplers and leads connection
Rust/dust/looseness/short-circuit
®

Repair or replace.
ENGINE STOP SWITCH INSPECTION
1. Inspect:
l
Engine stop switch conduct.
Not continuous while being pushed
®

Replace.
Continuous while being freed
®
Replace.
Tester (+) lead
®
Black/White lead
1

Tester (–) lead
®
Black lead
2

B/W
1
B
2
Tester selec-
tor position
PUSH IN
W

´
1
FREE