This next bike was one of my top two favorites of all the bikes. A twin engined Husaberg.
The output sprockets of both engines were connected to a jack-shaft which transferred power to the rear wheel.
To start it a remote starter is connected to the left motor, once it is running two guys lift the rear wheel off the ground, the rider lets the clutch out and the left motor starts the right motor. Cool!
A snowmobile engined hillclimber. This thing wailed like a banshee on it's run, lost momentum in the steepest part of the hill but then accelerated and made the top.