There is a 18 tooth sprocket on left side of cylinder shaft and it drives the thresher beater. There are 25, 30, and 35 tooth sprockets available for that position to speed up beater. Go as big as you need to to prevent pluging. Also if you have wires extending from rear of concave over thresher raddle you need to bend them down to just clear thresher raddle. Good luck. Dan