Adjustment securing means for an adjustment screw to a carburetor

The securing element screws a head portion (13) of adjustment screws (10,11) into a gasifier housing (2). A retained cap (20) made of plastic is fixed to a wall case (30) of gasifier housing. The adjustment screw is fixed to a rotational stopper (33) of housing. The cap is provided with a through aperture fixed to engagement holes (14,15) in the head of screw. The opening width of aperture is limited to the screw by a metallic material such as zinc, magnesium and aluminum, so that the maximum permissible adjustable moment of the engagement hole is limited.