7-10
SETTING
TUN
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
*#180
*#182
*#180
Jet needle
N3EW-3
N3EJ-2
N3CJ-2
N3CW-3
N3CW-3
N3CW-3
*N3CW-3
*N3EW-2
*N3CW-4
*N3EW-3
*N3EW-3
Pilot jet
#50
#50
#50
#52
#52
#52
Pilot air screw
-1/4
Zero
Zero
Zero
Zero
+1/4
*-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.
1P8-28199-10 256
04.5.12, 7:52:38 PM