Bajaj Discover 100M, Service Station Manual

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CARBURETTOR CIRCUITS
Discover 100 M
Service Station Manual
79
Dealer Development Center
Akurdi Pune
MAIN SYSTEM - High Speed System
Cap Throttle
Petrol Inlet
Venturi
Air
Intake
Air
Filter
Side
Needle
Valve
Main Jet
Pilot Jet
Float
Chamber
(Bowl)
Float
Fuel Level
Jet Needle
Needle Jet
Air Fuel
Mixer
Throttle
Valve
Magnet For
TPS
TPS
(Hall Sensor)
Air Screw
Spring
Engine
Side
Needle Jet
Clearance
Between
Jet needle
& needle Jet
Jet Needle
E Clip
2 from
Top Notch
(Std.)
nd
Air
(For Main Jet)
Side View
• This System consists of jet needle, needle jet and main jet. To assist in atomization, an air bleed circuit is
incorporated in the main metering system and it aids fuel vaporization by introducing air into the fuel before it enters
the air stream.
• For VM type the midrange circuit is actually a combination of circuits that work together to achieve correct air fuel
mixture. The pilot circuit is still operational but its contribution to the total air fuel mixture is relatively less.
• The jet needle is a tapered needle attached to the throttle valve which points downward, through the centre of
carburettor venturi. The tapered end of the jet needle moves inside the needle jet which is located in the carburettor
body.
• The position of the jet needle relative to the needle jet determines the amount of fuel flowing through the clearance
between them.
• Changing the position of the jet needle relative to the slide (Throttle Valve) changes the air fuel mixture. The jet
needle is moved relative to the slide by changing the position of the ‘ e- clip’ up or down in the grooves on the jet
needle. Moving the ‘e-clip’ towards the top of the needle has the effect of reducing the fuel flow, thus leaning out
the mixture. Bringing the ‘e-clip’ towards the lower grooves will have the effect of richening the mixture.
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