Four strokes, Water cooling, Inline, injecting combustion chamber Item/ModelR6105ZD1R6105IZLDR6105AZLDR6113ZLDR4105ZD1K4100DK4102DTypeSix strokes, Water cooling, Inline, injecting combustion chamberSix strokes, Water cooling, Inline, injecting combustion chamberSix strokes, Water cooling, Inline, injecting combustion chamberSix strokes, Water cooling, Inline, injecting combustion chamber.Six ...