The petrol level is maintaineed by a float and needle valve and is nocircumstance, should any alteration be made to these parts. In the event of a leaky float or aworn needle valve, the part should be replaced with new.
( Tips from TiranaAduka do not attempt a grind a needle to it's seat)
The petrol supply to the engine is controlled, firstly , by the main jet and, secondly by means of a taper needle which is attached to the throttle valve and operates in a tubular extension of the main jet.
The main jet controls the mixture fron three-quarters to full throttle, the adjustable taper needle fron three-quartes down to one-quartes throttle, the cut awat partson of the intake side of the throttle valve fron one-quater dwon to about one-eighth throttle, and a pilot jet having an independently adjusted air suply, takes care of the idling fron one-eighth throttle down to the almost closed position.
These various stage og control must be kept in mind when any adjustment is contemplate.
With the standart setting it is possible to use nearly air in all conditions, except.perhaps , when the engine is pulling hard up hill or is on full throttle , when some benefit may be obtained by slightly closing the air control. Weak maxture is always indicated by popping or spiting at the air intake.
A rich mixture usually causes bumpy or jerky,running and, in cases of extreme richness, is accompanied by the emmision of black smoke from the exhaust.