Slow Jet; Air Screw - Suzuki RM250 Owner's Service Manual

MACHINE TUNING 4·2
As shown below, each of the asterisk
(*)
marked parts is located bet ween the air/fuel passage and
has its own air/fuel mixture adjustable range in terms of the throttle valve opening. The chart indi-
cates that the carburetor can supply correct air/fuel mixture to the engine in any range because of
the overlapping adjustable range of the each part .
TUNING PARTS THROTTLE VALVE OPENING
MAIN JET
JET NEEDEL CLIP POSITION
JET NEEDLE 0.0 .
SLOW JET AND AIR SCREW
THROTTLE OPENING
' I '
CD
MAIN SYSTEM
®
INTERMEDIATE SYSTEM
®
SLOW SYSTEM
When performing carburetor tuning first find out
in what throttle opening range an improper
air/fuel mixture is supplied, by checking the color
of exhaust smoke, spark plug , throttle response ,
power, etc. Second , replace or adjust the part(s)
related to the throttle opening range by refer-
ring to the following instructions . The sizes
referred to in the illustrations are those of stan-
dard setting.
Slow Jet
The slow jet meters the fuel supplied to the slow
system , Each jet size is indicated by a number.
Larger number means a larger bore diameter and
fitting a larger numbered slow jet en riches the
air/fuel mixture.
Air Screw
The air screw is located in the inlet air passage
and meters the air for the slow system. As it has
a right-hand thread, tightening it makes the pas- .
sage narrower, allowing less amount of intake
air to flow and resulting in richer air/fuel mix-
ture . Air flow adjustment is effective within a
range of 1/2 - 2 turns out.