Effects Of Setting Parts In Relation To Throttle Valve Opening; Main Jet Adjustment; Powet Jet Adjustment - Yamaha YZ250(N)/LC Owner's Service Manual

Yz series
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SETTING
EC714032
Effects of setting parts in relation to throt-
tle valve opening
Setting part
Pilot jet
Pilot air screw
Diameter of
straight portion
Clip position
Throttle valve
Power jet
Main jet
NOTE:
The power jet closes at 8,500 rpm of the engine,
after which only the main jet dominates.
1 Throttle valve opening
2 Full-open
3 Full-closed
EC715002

Main jet adjustment

The richness of air-fuel mixture with 3/4~4/4
throttle can be set by changing the main jet 1.
Standard main jet
*For EUROPE
1. Spark plug is too hot.
Select a main jet having higher calibrating
No. than standard. (To be enriched)
2. Spark plug is wet.
Select a main jet having lower calibrating No.
than standard. (To be leaned out)
EC71V000

Powet jet adjustment

The richness of air-fuel mixture under 8,500 rpm
to the extent of 1/2 to full opened throttle can be
set by changing the power jet 1. A larger size jet
results in a richer mixture, and a smaller size in a
leaner mixture.
Standard Power jet
*For EUROPE
7-3
TUN
Throttle valve opening
Full-closed 1/4
1/2
3/4 Full-open
#178
*#180
#50
*#55

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Yz250s 2004Yz250 lcYz250lcYz250n1Yz250Yz250(n)

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