The carburetor of your FX Engines are set at the factory, before they are put in box, to obtain a setting for an easy start of your engine. If you are in trouble with your carburetor setting, we propose you a simple way to get back to the initial factory setting positions.

The needle-valve (A) is in charge to adjust the quantity of fuel necessary for the engine when the slide of the carburetor is full opened. For a correct position, turn the needle-valve (clockwise) until it stops. It’s the fully closed position (WARNING: do not force it to turn further). The needle-valve position is approximately 4.5 turns opened from the fully closed position (like mentioned on the drawing).

The metering needle (B) situated on the throttle is in charge to adjust the fuel debit when the throttle is moving with the gas servo. The position of this needle must be set for the best response of the engine during accelerations. The factory setting is like mentioned on the drawing.

The throttle stop screw (C) of your carburetor is used to adjust the air debit when the throttle is in the closed position (minimum RPM idle speed).  It must be turned to obtain a throttle setting of approximately 0.6 mm open once the throttle is closed (like mentioned on the drawing).

WARNING :
These settings help you to start your engine. The final setting is possible only after a complete running-in procedure. The final setting for an optimal performance is according to different things like the fuel you use, the weather, the car used (clutch system), tracks and your driving style.