Royal Enfield 350 BULLET 1989 Workshop Maintenance Manual Download

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WORKSHOP MANUAL BULLET

Page 75

the second groove (from top) in its lock washer. When assembling make sure that the jet needle can
move freely in the slide. The lock washer must be put with its outer fork into the narrow rim inside
the throttle slide so that the space in the slide for fixing the cable is not obstructed. Then place on
the lock  washer a  Disc  which  has four  cut  out  portions  to  accommodate  the rims  inside  the  slide.
The  latter  ensure  that  the  throttle  slide  spring  presses  only  on  the  throttle  slide  itself.  When  the
throttle slide is only slightly open the so-called ‘CUTAWAY’ in the slide, i.e. a small space at the
lower  edge  of  same,  has  an  additional  influence  on  the  fuel  quantity  delivered.  A  small  cutaway
causes an enriched fuel mixture in that range and vice versa.

IDLING SYSTEM

For idling of the engine the throttle slide is closed to the point where it touches the

throttle

stop screw. With this screw the idling r.p.m can be varied. Turning clockwise increases the idling
speed and vice versa. The throttle stop screw is prevented from loosening by spring.

In the idling position the vacuum at the needle jet outlet is so small that no fuel is delivered

through the main control system. The fuel to be mixed with the indrawn air in this range is
delivered through a supplementary system.

The fuel coming from the float bowl feeds the idling jet which regulates the fuel quantity.

Behind the jet orifice air is added through holes at the jet needle. The quantity of air is determined
by the position of the air adjusting screw. The

preliminary mixture enters the carburettor bore

through the idling outlet where a further mixture with filtered air takes place. The air adjusting
screw is secured with a spring.

Setting of the air adjusting screw is as follows:

Close fully by turning clockwise and open (anti-clockwise) by 2 turns.

The setting indicated can give only general data. Sometimes it may be necessary to readjust.

This should always be done when the engine is warm.

Select the desired idling speed with the throttle stop screw as described above. The air

adjusting screw is now opened (anti-clockwise) till the speed increases slightly. Then close the
screw again a quarter turn.

The adjusting screw for cable of the throttle slide must be turned into a point where the outer

cable has about 3 mm play. This guarantees that in idling the throttle slide touches the throttle stop
screw, and the cable does not interfere with the setting of the idling. The cable should be lubricated
from time to time.

STARTING SYSTEM

To enrich the mixture drawn in (especially for starting a cold engine) the carburetter

incorporates a secondary much smaller and simpler slide carburetter. i.e. a so-called starting
carburetter. When its slide-the starting piston is lifted by means of a lever against the pressure of
spring the engine suction delivers additional fuel through starting jet Std and its standpipe. During
this operation the throttle slide is fully closed.

SERVICING OF THE CARBURETTER

Cleaning the carburetter which may be necessary from time to time, depending on the amount

of dust present is done best with petrol. First clean the outside of the carburetter. Always use
suitable tools for taking it apart.

Check whether All parts are still in perfect condition. Worn-out float needles, needle jets, jet

needles and throttle slides should be replaced as they are mentioned before considerably affect the
power and consumption of the engine. Clogged jets should be cleaned by blowing through never
clean with a hard object. If necessary clean also the idling outlet hole either with compressed air or
a wood splinter. Damaged gaskets should be replaced. Please note that when fitting spare parts only

the use of GENUINE BING Spare parts guarantee satisfactory performance of the carburetter.

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