This compact cylinder with a 54mm bore features a cutting-edge power valve unit with a sophisticated mechanism for the lateral support exhaust ports. Matched to a twin-component cylinder head, it is KTM’s secret to all-round grunt. The layout of the water jackets in the cylinder and head guarantees efficient heat dissipation when the going gets tough. A 150cc cylinder, head and piston unit can now also be fitted to this engine base, converting it to a 150 without replacing the crankshaft. And to top this power pack off, lightweight, lateral brackets allow an efficient fixation of the engine to the frame. What’s not to like?