RIJNNING AD JIJSTMENTS
-
Engine
air cleaners and run the engine until it has attained its normal running
temperature, slacken one of the clamping bolts
(B)
on the throttle spindle
connection and disconnect the mixture control link
(G)
by removing one
of the fork swivel pins. Adjust the idling speed to approximately
500
r.p.m. by moving each throttle adjusting screw
(A)
Sr
(C)
an equal
amount.
By
listening to the hiss in the intakes, adjust the throttle adjusting
screws until the intensity of the hiss is similar on both intakes. This will
synchronise the
thrortlcs. When this is satisfactory, the mixture should
be adjusted by screwing both the jet adjusting nuts
(E)
up or down to
exactly the same extent, at the same time keeping the jet levers
iF',
pressed forward to ensure that the jets are hard up against the nuts, until
even running is obtained. As these are adjusted, the engine will probably
run faster, and it may therefore
be
necessary to vilscrew the throttle
adjusting screws a litt!e, each by the same amount, in order to reducc the
speed.
When the mixture is correct on both carburettors, lifting the piston
of one of them with a penknife blade should make the engine beat
hccome
irregular from excessive weakness. If liftiilg the piston about
!''
(3
mm.j
on one carburettor stops the engine and
lifting the
orher about
!"
increases the engine speed, this indicates that the mixcur; on the first
carburettor is set weak and the second is set rich. The first one should,
therefore, be enriched by unscrewing
tke jet adjusting nut one flat at a
time and the second should be weakened off by
screwing up the jet
adjusting nut in a similar manner.
When the mixture is correct, the
exhaust beat should be regular and even.
If it is irregular, with the splashy type of misfire and a colourless exhaust,
the mixture is too weak. If there is a regular or rythmical type of misfire in
thc exhaust beat, together with a blackish exhaust, then the mixture is too
rich. This should be noted when the air cleaners are again in position.
When reconnecting the mixture control link, make sure that the
jet levers
are
presyed forward and the control rod adjusted correctly for length so
that the clevis
pills may be inserted freely while the jets are in this position.
The throttle spindle
i!~terconnection clamping bolts
(B)
should now be
tightened.
The desired fast idle necessary when the choke is in operation is con-
trolled by adjusting screw
(D).
For further information on the tuning, adjustment and maintenance of
S.IJ. carburettors, you are advised to get in touch with the S.U. Car-
burettor Co. Ltd., Wood Lane, Erdington, Birmingham
24,
from whom
the necessary literature may be obtained.
Fuel Pump
The mechanically operated fuel pump, mounted on the left-hand side of
the crankcase, provides a constani pressure of fuel to the
carbvrettor.
A
hand primer is fitted, which can be used to pump fuel to the carburettors
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