O.S. Engines 7B Carb - 26781008 - Manual (Page 2)

(b) If instead of being set too rich, the Mixture Control
Screw is set too lean, the engine will stop when the throttle is
closed, or will lose speed while idling and then cut-out
abruptly (without smoking) when the throttle is opened again.
In this case, turn the Mixture Control Screw about one-half
turn counter-clockwise.
Mixture Control Screw adjustment is not critical and by
remembering the symptoms of rich and lean running quoted
above, it is a very simple matter to establish the best setting.
III. The Throttle Rotor Set-Screw is for establishing the
minimum idling speed. If the engine runs too fast with the
throttle closed, the Rotor Set-Screw should be turned
counter-clockwise to allow the throttle opening to be reduced.
CARBURETTOR INSERT
A muffler pressurised fuel system should be used with the Type
7B carburettor for best results. If, however, ordinary suction
feed is to be used, it is advisable to fit the carburettor insert,
which is supplied, as follows:
(1) Unscrew rotor set-screw and remove rotor.
(2) Remove the mixture control screw.
(3) Insert the carburettor insert into the throttle rotor throat.
(4) Reassemble carburettor.
SUBSEQUENT OPERATION AND CARE
Once the required settings have been established it should be
unnecessary to alter them. Such slight needle-valve alterations
as may be necessary to cope with differences in atmospheric
conditions or fuels, do not affect the other two adjustments.
The engine should start readily with the throttle in the idle
position.
It is important that the carburettor operates under clean
conditions. Make sure that fuel is properly filtered before use.
We advise fitting a filter to your fuel can and another filter in
the delivery tube between tank and engine, to reduce the risk
of the carburettor jet becoming partially clogged and upsetting
running adjustments.
PARTS LIST
Description
Carburettor Complete
Rotor spring
Throttle lever
Hex key wrench
Throttle lever set-screw
Rotor set-screw Assembly
Needle valve Assembly
Throttle f i x i n g screw
Carburettor gasket
7B Code No.
2 6 7 8 1 0 0 8
2 6 7 8 1 5 0 6
2 6 7 8 1 4 0 2
2 6 3 8 1 5 4 8
2 6 3 8 1 5 0 1
2 6 7 8 1 6 1 9
2 6 8 8 1 9 3 1
2 5 0 8 1 7 0 0
2 2 1 1 5 0 0 2
5B Code No.
2 5 1 8 1 0 0 9
2 6 7 8 1 5 0 6
2 6 7 8 1 4 0 2
2 6 3 8 1 5 4 8
2 6 3 8 1 5 0 1
2 6 7 8 1 6 1 9
2 4 9 8 1 9 3 0
2 5 0 8 1 7 0 0
2 2 1 1 5 0 0 2
4BK Code No.
2 4 9 8 1 0 2 9
2 6 7 8 1 5 0 6
2 4 9 8 1 4 0 5
2 6 3 8 1 5 4 8
2 6 3 8 1 5 0 1
2 6 7 8 1 6 1 9
2 6 7 8 1 9 3 8
2 5 0 8 1 7 0 0
2 2 1 1 5 0 0 2
4D Code No.
2 5 3 8 1 0 0 6
2 6 7 8 1 5 0 6
2 4 9 8 1 4 0 5
2 6 3 8 1 5 4 8
2 6 3 8 1 5 0 1
2 6 7 8 1 6 1 9
2 4 9 8 1 9 3 0
2 5 0 8 1 7 0 0
2 2 1 1 5 0 0 2
4E Code No.
2 5 3 8 3 0 0 0
2 6 7 8 1 5 0 6
2 4 9 8 1 4 0 5
2 6 3 8 1 5 4 8
2 6 3 8 1 5 0 1
2 6 7 8 1 6 1 9
2 6 7 8 1 9 3 8
The specification is subject to alteration for improvement without notice.
6-15 3-chome Imagawa Higashisumiyoshi-ku
Osaka 546, Japan. TEL. Osaka (06) 702-0225