BSABOB,
Your hand is acting like a 'choke' effectively reducing the amount of air so increasing the ratio of fuel to air that is drawn into the engine. Has this recently been required or has it been needed for a long time? This could be down to wear and/or incorrect adjustments. I haven't 'fiddled' with any Amal carbs for 30 years but has yours got a 'tickling' button to push the float down inside the carb. I remember having to tickle my bonnie to get the fuel flowing and it started a treat. My duke, however, just had accelerator pumps that squirted fuel in if you twisted the throttle either method increased the fuel as neither bike had chokes fitted.
