brake YAMAHA YZ250LC 2003 Workshop Manual

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)
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5-24
CHASFRONT BRAKE AND REAR BRAKE
2. Install:
9Brake hose holder 1
9Screw (brake hose holder) 2
cC
After installing the brake hose holders,
make sure the brake hose does not contact
the spring (rear shock absorber). If it does,
correct its twist.
EC5A5601
Brake fluid
1. Fill:
9Brake fluid
Until the fluid level reaches “LOWER” level
line a.
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9Use only the designated quality brake fluid:
otherwise, the rubber seals may deterio-
rate, causing leakage and poor brake per-
formance.
9Refill with the same type of brake fluid;
mixing fluids may result in a harmful chemi-
cal reaction and lead to poor performance.
9Be careful that water does not enter the
master cylinder when refilling. Water will
significantly lower the boiling point of the
fluid and may result in vapor lock.
cC
Brake fluid may erode painted surfaces or
plastic parts. Always clean up spilled fluid
immediately.
AFront
BRear
Recommended brake fluid:
DOT #4
1 Nm (0.1 m•kg, 0.7 ft•lb)
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5-25
CHASFRONT BRAKE AND REAR BRAKE
2. Air bleed:
9Brake system
Refer to “BRAKE SYSTEM AIR BLEED-
ING” section in the CHAPTER 3.
3. Inspect:
9Brake fluid level
Fluid at lower levelFill up.
Refer to “BRAKE FLUID LEVEL INSPEC-
TION” section in the CHAPTER 3.
4. Install:
[Front]
9Diaphragm
9Master cylinder cap 1
9Screw (master cylinder cap) 2
[Rear]
9Diaphragm
9Master cylinder cap 1
9Bolt (master cylinder cap) 2
cC
After installation, while pulling the lever in
or pushing down on the pedal, check
whether there is any brake fluid leaking
where the union bolts are installed respec-
tively at the master cylinder and caliper.
AFront
BRear
5. Install: (rear brake only)
9Protector 1
9Bolt (protector) 2
2 Nm (0.2 m•kg, 1.4 ft•lb)
2 Nm (0.2 m•kg, 1.4 ft•lb)
7 Nm (0.7 m•kg, 5.1 ft•lb)
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5-26
CHASFRONT FORK
Extent of removal Order Part name Q’ty Remarks
FRONT FORK REMOVAL
Preparation for
Hold the machine by placing the
removalsuitable stand under the engine.
Front wheel Refer to “FRONT WHEEL AND
REAR WHEEL”section.
Front caliper Refer to “FRONT BRAKE AND
REAR BRAKE”section.
Number plate
1 Protector 1
2 Brake hose holder 2
3 Pinch bolt (handle crown) 2 Only loosening.
4 Cap bolt 1
Loosen when disassembling the front fork.
5 Pinch bolt (under bracket) 2 Only loosening.
6 Front fork 1
1
w
Support the machine securely so there is no dan-
ger of it falling over.
Extent of removal:1Front fork removal
4 Nm (0.4 m•kg, 2.9 ft•lb)
20 Nm (2.0 m•kg, 14 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
23 Nm (2.3 m•kg, 17 ft•lb)
EC550000
FRONT FORK
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5-38
CHASFRONT FORK
7. Adjust:
9Rebound damping force
NOTE:
Turn in the damping adjuster 1finger-tight and
then turn out to the originally set position.
4. Tighten:
9Pinch bolt (handle crown) 1
9Pinch bolt (under bracket) 2
cC
Tighten the under bracket to specified
torque. If torqued too much, it may cause
the front fork to malfunction.
5. 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.
6. Install:
9Brake hose holder 1
9Bolt (brake hose holder) 2
9Protector 3
9Bolt (protector) 4
NOTE:
When installing the brake hose holder, align the
top aof the brake hose neck with the brake
hose holder bottom b. Then pass the brake
hose 5in front of the axle boss cand fit it into
the hose groove dso that the brake hose does
not contact the nut (wheel axle).
23 Nm (2.3 m•kg, 17 ft•lb)
20 Nm (2.0 m•kg, 14 ft•lb)
23 Nm (2.3 m•kg, 17 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
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5-41
CHASHANDLEBAR
EC5B3000
REMOVAL POINTS
EC5B3100Master cylinder
1. Remove:
9Master cylinder bracket 1
9Master cylinder 2
cC
9Do not let the master cylinder hang on the
brake hose.
9Keep the master cylinder cap side horizontal
to prevent air from coming in.
EC5B3200
Grip
1. Remove:
9Grip 1
NOTE:
Blow in air between the handlebar or tube guide
and the grip. Then remove the grip which has
become loose.
EC5B4000
INSPECTION
EC5B4100
Handlebar
1. Inspect:
9Handlebar 1
Bends/Cracks /DamageReplace.
w
Do not attempt to straighten a bent handlebar
as this may dangerously weaken the handlebar.
EC5B5000
ASSEMBLY AND INSTALLATION
EC5B5100
Throttle assembly
1. Install
9Grip (right) 1
Apply the adhesive on the tube guide 2.
NOTE:
9Before applying the adhesive, wipe off grease
or oil on the tube guide surface awith a lac-
quer thinner.
9Align the mating mark bon the grip (right) with
the slot cin the tube guide.
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5-44
CHASHANDLEBAR
10. Install:
9Bolt (grip cap) 1
w
9Install the grip cap so that the gaps a a
and
b b
between the bolt (grip cap) and brake
lever 2 2
are equal. If you make a mistake in
the grip cap installation position, the brake
lever may contact the grip cap, resulting in
poor brake performance.
9After tightening the bolts, check that the
throttle grip 3 3
moves smoothly. If it does
not, retighten the bolts for adjustment.
11. Install:
9“ENGINE STOP” button 1
9Clutch lever holder 2
9Bolt (clutch lever holder) 3
9Clamp 4
NOTE:
9The “ENGINE STOP” button, clutch lever hold-
er and clamp should be installed according to
the dimensions shown.
9Pass the “ENGINE STOP” button lead in the
middle of the clutch holder.
12. Install:
9Clutch cable 1
NOTE:
Apply the lithium soap base grease on the clutch
cable end.
13. Adjust:
9Clutch lever free play
Refer to “CLUTCH ADJUSTMENT” section in
the CHAPTER 3.
4 Nm (0.4 m•kg, 2.9 ft•lb)
4 Nm (0.4 m•kg, 2.9 ft•lb)
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5-51
CHASSWINGARM
Extent of removal Order Part name Q’ty Remarks
SWINGARM REMOVAL
Preparation for
Hold the machine by placing the
removalsuitable stand under the engine.
Brake hose holderRefer to “FRONT BRAKE AND
Rear caliperREAR BRAKE”section.
Bolt (brake pedal) Shift the brake pedal backward.
Drive chain
1 Chain support 1
2 Chain tensioner (lower) 1
3
Bolt (rear shock absorber-relay arm)1 Hold the swingarm.
4 Bolt (connecting rod) 1
5 Pivot shaft 1
6 Swingarm 1
EC570000
SWINGARM
Extent of removal:1Swingarm removal
1
w
Support the machine securely so there is no dan-
ger of it falling over.



53 Nm (5.3 m•kg, 38 ft•lb)
80 Nm (8.0 m•kg, 58 ft•lb)
19 Nm (1.9 m•kg, 13 ft•lb)
7 Nm (0.7 m•kg, 5.1 ft•lb)
85 Nm (8.5 m•kg, 61 ft•lb)
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7-11
SETTINGTUN
Symptom Setting Checking
0~1/4 throttle Use jet needle having a smaller Number of turns-back 
Hard breathing diameter. Correct properly
Speed down Overflow from carburetor
0~1/4 throttle Use jet needle having a larger
Poor acceleration diameter.
White smoke
Unstable at low speeds Lower jet needle clip position.
Pinking noise (1 groove down)
Turn in pilot air screw.
Poor response at extremely Reduce pilot jet calibration No. Dragging brake
low speed Turn out pilot air screw. Overflow from carburetor
If not effect, reverse the above
procedures.
Poor response in the Raise jet needle clip position.
range of low to If no effect, reverse the above
intermediate speeds procedures.
Poor response when Check overall settings. Check air cleaner for fouling.
throttle is opened quickly Use main jet having lower
calibration No.
Raise jet needle clip position.
(1 groove up)
If no effect, reverse the above
procedures.
Poor engine operation Turn in pilot air screw. Check throttle valve operation.
This should be taken simply for an example.
It is necessary to set the carburetor while
checking the operating conditions of the
engine and discoloration of spark plugs.
Normally, carburetor setting is made by
means of the main jet, needle clip position,
pilot jet and pilot air screw. If the result of
setting is still unsatisfactory, it is advisable to
change the sizes of the jet needle.
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