TUN
9-3
MAIN JET ADJUSTMENT
The richness of air-fuel mixture with 3 / 4 ~ 4 / 4
throttle can be set by changing the main jet
.
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)
PILOT AIR SCREW ADJUSTMENT
The richness of the air-fuel mixture with the
throttle fully closed to 1 / 4 open can be set by
turning the pilot air screw
.
Turning in the pilot air screw will make the mix-
ture enrich at low speeds, and turning it out will
lean it.
PILOT JET ADJUSTMENT
The richness of air-fuel mixture with the throttle
fully closed to 1 / 2 open can be set by turning
the pilot jet
. It is changed when adjustment
cannot be made by the pilot air screw alone.
A larger size jet results in a richer mixture at
low speeds, and a smaller size in a leaner mix-
ture.
JET NEEDLE ADJUSTMENT
The richness of air-fuel mixture with 1 / 4 ~ 3 / 4
throttle can be set by changing the jet needle
.
A smaller diameter jet needle results in a richer
mixture at middle speeds, and a larger diame-
ter in a leaner mixture.
Standard main jet
#138
Standard pilot air
screw position
2 turns out
Standard pilot jet
#45
Standard jet needle
NBKF
ENGINE
