Disconnect the downshift cable from the crank arm at the carburettor and remove the air cleaner. Have an assistant depress the accelerator pedal fully, compressing the 'kick-down' stop. Check that the throttle valve plate is in the fully open (vertical) position by looking down the carburettor throat. If it is not, bend the stop to correct the attitude of the plate or adjust the length of the accelerator linkage (clevis fork and locknut) as appropriate. With the assistant holding the accelerator pedal fully depressed, pull the downshift cable to its fully extended position. The hole in the clevis fork at the end of the cable should be in exact alignment with the hole in the crank arm on the throttle shaft. If not, adjust the cable clevis fork locknuts as necessary. Reconnect the cable to the crankarm and test kickdown operation on the road.