preferably of rectangular shape in section the insert port 82 is reinforced by a pair of reinforcing ribs 84 and communicated with the receiving cylinder 81 through the slit 83 as shown in fig1 a self tapping hole for an adjustment bolt 86 is provided on the upper side of the slit 83 in the cable holder 80 the adjustment bolt 86 projects toward the receiving cylinder 81 and comes in contact with the metal cover 90 or the end of the outer tube 91 through a thrust washer 87 so that an axial position of the end of the outer tube 91 with respect to the receiving cylinder 81 may be adjusted the left end surface of the cable holder 80 constitutes a stop wall 96 of the rotary throttle valve that is engaged by the throttle valve lever 8 when the throttle valve 15 is in its wide open position when the remote control cable is mounted on the carburetor the end of the inner wire 89 is inserted into the insert port 82 and the end of the outer tube 91 is fitted in the receiving cylinder 81 since the inner wire 89 crosses the slit 83 while the end of the outer tube 91 is pushed into the receiving cylinder 81 the end of the outer tube 91 comes in contact with the adjustment bolt 86 through the thrust washer 87 and the inner wire 89 projects through the stop wall 96 then the end of the inner wire 89 is drawn out of the slit 83 and engaged on the split groove 10 a.