The bike was more than likely an Indian ,they had a left hand throttle [with a foot clutch]..
Ostensibly so that American cops could shoot right handed at fleeing criminals ,but actually because the very early bikes had a right hand control that altered the ignition timing and thereby the speed of the engine .
When a throttle was developed they just put it on the left as the right handlebar was already occupied .
Blessed are the cracked, for they let in the light. - Spike Milligan
"When you come to a fork in the road ,take it ! When you come to a spoon in the road ,take that also ."