2002 YAMAHA YZ250LC light

5-24
CHASFRONT BRAKE AND REAR BRAKE
EC5A5501
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 adirects as show and lightly touches
the projection
b bon the master cylinder.
30 Nm (3.0 m•kg, 22 ft•lb)
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 show and lightly touches
the projection b b
on the master cylinder.
30 Nm (3.0 m•kg, 22 ft•lb)
5NX-9-30-5A 6/7/01 2:00 PM Page 48

7-10
SETTINGTUN
EC71D021
Examples of carburetor setting depending on symptom
Symptom Setting Checking
At full throttle Increase main jet calibration No. Discoloration of spark plug 
Hard breathing (Gradually) If tan color, it is in good condition.
Shearing noise If can not be normalized:
Whitish spark plug Clogged float valve seat
Clogged fuel hose
Lean mixture Clogged fuel cock
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:
Slow response of mixture reduces engine trouble. Clogged air cleaner
Sooty spark plug Fuel overflow from carburetor
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. Clip position indicates the position of
Slow speed pick-up (1 groove up) jet needle groove, to which the clip is
White smoke fitted. The position is numbered from
Poor acceleration the top.
Leaner
(Standard)
Richer


EC71C030
Road condition and examples of carburetor setting
Conditions General condition Sandy condition
Under 10°C 10~25°C Over 25°C Under 10°C 10~25°C Over 25°C
(50°F) (50~77°F) (77°F) (50°F) (50~77°F) (77°F)
Parts (Winter)(Spring, Autumn)(Summer) (Winter)(Spring, Autumn)(Summer)
Main jet #178 #178#178 #180 #178 #178
*#175 *#178 *#175 *#175
Jet needleN3EW-3 N3EJ-2 N3CJ-2
N3CW-3 N3CW-3 N3CW-3
*N3CW-3 *N3EW-2 *N3EW-2
Pilot jet #50 #50 #50 #52 #52 #52
Pilot air screw-1/4
Zero ZeroZero
Zero +1/4
*Zero *-1/4
Power jet #50 #50 #50 #50 #50 #50
*For EUROPE
NOTE:
Optimum pilot air screw setting can be abtained by adding the ex-factory number of the same screw
back-out turns to any required value provided in the chart.
For example, if the ex-factory number is “1”, add “1” to the value chosen in the chart.
5NX-9-30-7 6/5/01 4:47 PM Page 20

7-12
SETTINGTUN
EC71M001
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 spark plugs other than standard,
make sure of the difference in heat range and
find the equivalent to the standard.
9Note that even if the discoloration seems prop-
er, it may slightly vary with the spark plug
maker and oil in use.
Standard spark plug BR8EG/NGK
5NX-9-30-7 6/5/01 4:47 PM Page 28