1998 YAMAHA T105 Owners Manual

EAH20304Spark plug inspection
The spark plug is an important engine
component and is easy to inspect. The con-
dition of the spark plug can indicate the
condition of the engine. The ideal color on
the white insulator around the center elec-
trode is a medium-to-light tan color for a
motorcycle that is being ridden normally.
Do not attempt to diagnose any problems
yourself. Instead, take the motorcycle to a
Yamaha dealer. You should periodically re-
move and inspect the spark plug because
heat and deposits will cause the spark plug
to slowly break down and erode. If elec-
trode erosion becomes excessive, or if car-
bon and other deposits are excessive, you
should replace the spark plug with the
specified plug.
48
Standard spark plug:
C6HSA/NGK or U20FS-U/
NIPPONDENSO
1Spark plug gap
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Before installing the spark plug, measure
the electrode gap with a wire thickness
gauge; adjust the gap to specification as
necessary.
When installing the plug, always clean the
gasket surface and use a new gasket. Wipe
off any grime from the threads and tighten
the spark plug to the specified torque.EUU03801NOTE:
If a torque wrench is not available when
you are installing a spark plug, a good esti-
mate of the correct torque is 1/4 to 1/2 turn
past finger tight. Have the spark plug
torqued to the correct value as soon as
possible with a torque wrench.
49
Spark plug gap:
0.6 ~ 0.7 mmSpark plug torque:
12.5 Nm (1.25 m•kg)
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EAH85201Front brake adjustment
The front brake lever free play should be
adjusted to 8~12 mm at the brake lever
end. Adjustment is accomplished at the
front brake hub. To adjust, turn the adjuster
clockwise to reduce play or counterclock-
wise to increase play.
50
a
A. Free play: 8~12 mm1Adjuster
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Rear brake adjustment
The rear brake pedal free play should be
adjusted to 20~30 mm at the brake pedal
end. Turn the adjuster on the brake rod
clockwise to reduce play or counterclock-
wise to increase play.EUU69800w1. The rear brake pedal adjustment must
be checked whenever the chain is ad-
justed or the rear wheel is removed
and then reinstalled.
2. Check the operation of the brake light
after adjusting the rear brake.
51
A. Free play: 20~30 mm1Adjuster
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EAH83301Brake light switch adjustment
The brake light switch is operated by
movement of the brake pedal. To adjust,
hold the main body of the switch so it does
not rotate and turn the adjusting nut.
Proper adjustment is achieved when the
brake light comes on just before the brake
begins to take effect.EAH81601Checking the brake shoes
A wear indicator is provided on each brake.
This indicator allows checking of shoe
wear without disassembling the brake.
Apply the brake and check the position of
the indicator. If the indicator reaches to the
wear limit line, ask a Yamaha dealer to re-
place the shoes.
52
1Brake light switch1Wear limit2Indicator
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EAI40001Drive chain slack checkEUU04801NOTE:
Spin the wheel several times and find the
tightest position of the chain. Check and/or
adjust the chain slack while it’s in this tight-
est position.Inspect the drive chain when the motorcy-
cle is on the centerstand. Check the slack at
the position shown in the illustration.
Normal slack is approximately 20~30 mm.
If the slack exceeds 30 mm, adjust it.
53
a. Drive chain slack: 20~30 mm
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Drive chain slack adjustment
1. Loosen the rear brake adjuster.
2. Loosen the axle nut.
3. Loosen the sprocket shaft nut and the
axle nut.
4. To tighten the chain, turn the chain ad-
juster clockwise. To loosen the chain,
turn the adjuster counterclockwise and
push the wheel forward. Turn each ad-
juster exactly the same amount to main-
tain correct axle alignment. There are
marks on each side of the swingarm and
a match mark on each chain puller. Use
these marks to align the rear wheel.EUU33301cCToo little chain slack will overload the en-
gine and other vital parts. Keep the slack
within the specified limits.
54
1Rear brake adjuster2Axle nut1Axle nut2Sprocket shaft nut
3Chain puller4Chain adjuster
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5. After adjusting, be sure to tighten the
loosened parts.
Tighten the axle nut at specified
torque.
6. Adjust the free play in the brake pedal.
55
Tightening torque:
Axle nut:
60 Nm (6.0 m•kg)
Sprocket shaft nut:
80 Nm (8.0 m•kg)
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