I had a 74 Yamaha 360 Enduro bored out with a Webber head and expansion pipe. It had so much back pressure and threw me off so often I had to install a compression release valve just to crank it. It once kicked back so hard it broke the sole of my boot. Whenever I went on an extended ride I took two spare plugs as that two stroke beast would foul them in a heart beat. Two strokes would go like stink but they were a PITA to maintain.