We had one of those John Deere tractors. It was a 30 something model. It started on gas and ran on kerosene. What gives a Harley its distinctive sound is the rods being together on a single crank pin. They both go up and down at the same time. As the crank rotates 360 degrees the cylinders are separated by 45 degrees so one cylender fires 45 degrees before the other one. That gives the Harley its loping idle and sound.