2003 YAMAHA YZ125LC light

5-18
CHASFRONT BRAKE AND REAR BRAKE
3. Install:
9Brake hose holder 1
9Caliper 2
9Bolt (caliper) 3
NOTE:
Fit the brake hose holder cut aover the projec-
tion bon the front fork and clamp the brake
hose.
4. Tighten:
9Pad pin 4
5. Install:
9Pad pin plug 5
EC5A5121
Rear caliper
1. Install:
9Pad support 1
9Brake pad 2
9Pad pin 3
NOTE:
9Install the brake pads with their projections
ainto the caliper recesses b.
9Temporarily tighten the pad pin at this point.
2. Install:
9Copper washer 1
9Union bolt 2
w
Always use new copper washers.
cC
Install the brake hose so that its pipe por-
tion a a
directs as shown and lightly touch-
es the projection b b
on the caliper.
30 Nm (3.0 m•kg, 22 ft•lb)
23 Nm (2.3 m•kg, 17 ft•lb)
18 Nm (1.8 m•kg, 13 ft•lb)
3 Nm (0.3 m•kg, 2.2 ft•lb)

5-21
CHASFRONT BRAKE AND REAR BRAKE
2. Install:
9Brake lever 1
9Bolt (brake lever) 2
9Nut (brake lever) 3
NOTE:
Apply the lithium soap base grease on the
brake lever sliding surface, bolt and contacting
surface of the master cylinder piston.
6 Nm (0.6 m•kg, 4.3 ft•lb)
6 Nm (0.6 m•kg, 4.3 ft•lb)
EC5A5401
Rear master cylinder
1. Install:
9Copper washer 1
9Brake hose 2
9Union bolt 3
w
Always use new copper washers.
cC
Install the brake hose so that its pipe por-
tion
a adirects as shown and lightly touch-
es the projection
b bon the master cylinder.
30 Nm (3.0 m•kg, 22 ft•lb)
2. Install:
9Master cylinder 1
9Bolt (master cylinder) 2
10 Nm (1.0 m•kg, 7.2 ft•lb)

5-23
CHASFRONT BRAKE AND REAR BRAKE
3. Pass the brake hose through the cable
guide 1, then through the guide aon the
protector 2.
4. Install:
9Copper washer 1
9Brake hose 2
9Union bolt 3
w
Always use new copper washers.
cC
Install the brake hose so that its pipe por-
tion a a
directs as shown and lightly touch-
es the projection b b
on the master cylinder.
30 Nm (3.0 m•kg, 22 ft•lb)
EC5A5502
Rear brake hose
1. Install:
9Copper washer 1
9Brake hose 2
9Union bolt 3
w
Always use new copper washers.
cC
Install the brake hose so that its pipe por-
tion a a
directs as shown and lightly touch-
es the projection b b
on the caliper.
30 Nm (3.0 m•kg, 22 ft•lb)

7-10
TUNSETTING
EC71C020
Road condition and examples of carburetor setting
EC71D040
Examples of carburetor setting depending on symptom
Symptom Setting Checking
At full throttle Increase main jet calibration No. Discoloration of spark plug

Stall at high speeds (Gradually) If tan color, it is in good condition.
* Hard breathing If can not be normalized:
Shearing noise Clogged float valve seat
Whitish spark plug Clogged fuel hose
Clogged fuel cock
Lean mixture
At full-throttle Decrease main jet calibration No. Discoloration of spark plug 
Stop of speed pick-up (Gradually) If tan color, it is in good condition.
Slow speed pick-up *In case of racing slight enrichment If not effect:
of mixture reduces engine trouble. Clogged air cleaner
Slow response Fuel overflow from carburetor
Sooty spark plug Clogged main air passage or clogged
filter
Rich mixture
Lean mixture Lower jet needle clip position.
(1 groove down)
Rich mixture Raise jet needle clip position.
(1 groove up)
1/4~3/4 throttle Lower jet needle clip position.
* Hard breathing (1 groove down)
Lack of speed
1/4~1/2 throttle Raise jet needle clip position.
Slow speed pick-up (1 groove up)
White smoke
Poor acceleration
Conditions General condition Sandy condition
Under 10°C 15~25°C Over 30°C Under 10°C 15~25°C Over 30°C
(50°F) (59~77°F) (86°F) (50°F) (59~77°F) (86°F)
Parts (Winter)(Spring, Autumn)(Summer) (Winter)(Spring, Autumn)(Summer)
Main jet #420 #410 #400 #440 #430 #420
Jet needle6CHY6-81-3 6CHY6-82-3 6CHY5-82-3 6CHY5-81-4 6CHY5-82-4 6CHY6-82-3*6CHY6-81-4 *6CHY6-82-4 *6CHY5-82-4 *6CHY5-81-5 *6CHY5-82-5 *6CHY6-82-4
Pilot jet #40 #40 #40 #40 #40 #40
Pilot air screw1-1/222
1-1/222
*1-1/2 *1-1/2 *1-1/2 *1-1/2
Leaner
(Standard)
Richer


Clip position indicates the position of jet
needle groove, to which the clip is fitted.
The position is numbered from the top.
If a change in the clip position (1
groove) is effective, try another jet nee-
dle that provides a difference of 0.5 in
the clip position.
*For EUROPE

7-12
TUNSETTING
EC71M010
Change of the heat range of spark plugs
Judging from the discoloration of spark plugs, if
they are found improper, it can be corrected by
the following two methods; changing carburetor
settings and changing the heat range of spark
plug.
9In principle, it is advisable to first use spark
plugs of standard heat range, and judging from
the discoloration of spark plugs, adjust carbure-
tor settings.
9If the calibration No. of the main jet must be
changed by ±30, it is advisable to change the
heat range of spark plugs and newly select the
proper main jet.
NOTE:
9When checking the discoloration of spark
plugs, be sure to stop the engine immediately
after a run and check.
9Avoid racing.
9When changing the heat range of spark plugs,
never attempt to change it more than ±1 rank.
9When using a spark plug other than standard,
check its heat range against the standard and
check that it is a resistance type.
9Note that even if the discoloration seems prop-
er, it may slightly vary with the spark plug
maker and oil in use.
Standard spark plugBR9EG/NGK(resistance type)