stop start YAMAHA YZ125LC 2002 User Guide

4-8
ENGCARBURETOR AND REED VALVE
EC468000
CARBURETOR DISASSEMBLY
Extent of removal Order Part name Q’ty Remarks
CARBURETOR DISASSEMBLY
1Mixing chamber top 1
2Throttle valve 1 Refer to “REMOVAL POINTS”.
3Needle holder 1
4Jet needle 1
5Float chamber 1
6Needle jet cover 1
7Float pin 1
8Float 1
9Valve seat 1
0Main jet 1
qMain jet holder 1
wPilot jet 1
eStarter plunger 1
rThrottle stop screw 1
tPilot air screw 1
Extent of removal:1Carburetor disassembly
1
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4-13
ENGCARBURETOR AND REED VALVE
2. Install:
9Reed valve assembly 1
9Reed valve spacer 2
NOTE:
Install the reed valve spacer with its wider con-
tact surface side ato the right.
3. Install:
9Carburetor joint 1
9Bolt (carburetor joint) 2
EC4652C2
Carburetor
1. Install:
9Throttle stop screw 1
9Locknut 2
9Pilot air screw 3
*For EUROPE
Pilot air screw:
2-1/2 turns out
*1-3/4 turns out
Note the following installation points:
9Screw in the pilot air screw until it is
lightly seated.
9Back out it by the specified number of
turns.
10 Nm (1.0 m•kg, 7.2 ft•lb)
2. Install:
9Starter plunger 1
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4-63
ENGCRANKCASE AND CRANKSHAFT
EC4N3000
REMOVAL POINTS
EC4N3100
Segment
1. Remove:
9Bolt (segment) 1
9Segment 2
NOTE:
Turn the segment counterclockwise until it stops
and loosen the bolt.
EC4N3212
Crankcase
1. Remove:
9Crankcase (right) 1
Use the crankcase separating tool 2.
NOTE:
9Make appropriate bolts 3as shown available
by yourself and attach the tool with them.
9Fully 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.
9As pressure is applied, alternately tap on the
front engine mounting boss and transmission
shafts.
cC
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-1135-A/90890-01135
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6-3
ELECIGNITION SYSTEM
EC622001
SPARK GAP TEST
1. Disconnect the spark plug cap from spark
plug.
2. Connect the dynamic spark tester 1(igni-
tion checker 2) as shown.
9Spark plug cap 3
9Spark plug 4
AFor USA and CDN
BExcept 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)
EC624000
COUPLERS AND LEADS CONNECTION
INSPECTION
1. Check:
9Couplers and leads connection
Rust/ Dust/ Looseness/Short-circuit 
Repair or replace.
EC625002
“ENGINE STOP” BUTTON INSPECTION
1. Inspect:
9“ENGINE STOP” button conduct
Not continuous while being pushed Replace.
Continuous while being freed Replace.
Minimum spark gap:
6.0 mm (0.24 in)
Tester (+) leadBlack/White lead 1
Tester (–) lead
Black lead 2
B/W B
12
PUSH IN
FREE
Tester selector
position
Ω× 1
å
∫
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