VHM has been the world leader in Two Stroke performance heads since 1978. In that time many World, National and Regional Championship Titles have been won in Motocross, Kart and Road Racing.
Heat is the enemy of especially 2 stroke engines, as the race goes on and the engine gets hotter, the power drops off. You have probably noticed your engine seems to have less power towards the end of the race, or you can’t clear a jump you were making at the beginning of the race.
The engineers at VHM looked at the problem and noticed that because stock heads were made by casting , the water jackets were small and rough, not at all conducive for optimal coolant flow. So it was that the idea of machining the head in two pieces was born to achieve a much better flow and thus better cooling.