Slow System - Suzuki VL800 Service Manual

SLOW SYSTEM

This system supplies fuel to the engine during engine operation with throttle valve 1 closed or slight opened.
The fuel from the float chamber 2 is first passage and metered by the pilot jet 3 where it mixes with air
coming in through #1 pilot air jet 4 and #2 pilot air jet 5.
This mixture, rich with fuel, then goes up through pilot pipe to pilot screw 6. A part of the mixture is dis-
charged into the main bore out of by-pass ports 7. The remainder is then metered by pilot screw and sprayed
out into the main bore through pilot outlet 8.
TRANSIENT ENRICHMENT SYSTEM
The transient enrichment system is a device which keeps fuel/air mixture ratio constant in order not to gener-
ate unstable combustion when the throttle grip is returned suddenly during high speed driving. For normal
operation, sum of the air from the #1 pilot air jet 4 and #2 pilot air jet 5 keeps proper fuel/air mixture ratio. But
when the throttle valve is closed suddenly, a large negative pressure generated on cylinder side works on to
a diaphragm 9. The ball 0 held by the diaphragm 9 closes the air passage from #2 pilot air jet 5, therefore,
the fuel/air mixture becomes rich with fuel.
This system is to keep the combustion condition constant by varying the fuel/air mixture ratio by controlling air
flow from the pilot air jet.
FUEL AND LUBRICATION SYSTEM 5-11
AIR
MIXTURE
FUEL