Main System - Suzuki DR650SE Shop Manual

FUEL AND LUBRICATION 4·8
MAIN SYSTEM
As throttle valve
CD
is opened, engine speed rises, and this increases negative pressure in the ventu-
ri
®.
Consequently the piston valve
@
moves upward.
Meanwhile, the fuel in float chamber
@
is metered by main jet
@ ,
and the metered fuel enters nee-
dle jet
® ,
in which it mixes with the air admitted through main air jet
®
to form an emulsion.
The emulsified fuel then passes through the clearance between needle jet
®
and jet needle
(J) ,
and
is discharged into the venturi
®,
in which it meets main air stream being drawn by the engine.
Mixture proportioning is accomplished in needle jet
® ;
the clearance through which the emulsified
fuel must flow in large or small, depending ultimately on throttle position.
<18::::::::::::::::::::::J
Fuel/Air mixture
~
Fuel