7. The 1972 250 and 175 Pioneer & Stiletto models incorporate a slightly different carburetor main body and jet block. (Figs. 129 & 130). This jet block is an integral part of the body, therefore, the metering passages can be held to closer tolerances. This eliminates the need for a booster system, therefore these 1972 OSSA's do not use such a system.
8. The proportion of the mixture at 1/2 throttle also affects the mixture
at wider throttle openings.