Theres probably several ways this arrangement could work,but you could be pretty sure the horse power figures wouldnt be to high.I would assume it contains a conrod arrangement simular to a Harley D because the barrels appear to be directly inline with each other,and it contains some form of rotary valve that may also have a system that masks the the transfer ports of the ajoining cylinder,at the right part of the stroke.But then again it may also be just sharing a common crankcase and to hell with the way it performs, and that proberbly explains why he sprayed areo start down the spout of the carby to get it fired up because with that arrangement it would run pretty horrible down low I would imagine with all that cross flow going on.Regards greg b .