The third engine in the new â‘ax ⒠range of high performance 2 stroke engines fills a convenient gap between the existing 61fx and 91fx, yet features the radical new style pioneered with the fabulous 55ax. The new 75ax is supplied complete with the latest â‘p-box ⒠design silencer for improved noise suppression. By keeping the lower crankcase dimensions the same as the 61fx, you can be sure that it will fit in all models designed for a. 61, making a power upgrade very simple. The 75ax features the latest o. S. Ringless piston technology with multi-layer cylinder coating and high precision type 61a carburettor with angled safety needle valve assembly.