Longer transmission without disassembling the engine? Especially interesting is this sprocket with 23 teeth. This one was never original ex works. It is designed to extend the gear ratio based on a 67/68 tooth primary gear as much as possible. So a 23/67 or 23/68 gear ratio can be used without having to open the engine. Ideal for all drivers of high capacity cylinders on e.g. original PX125 or Sprint 150 engines. It even fits into the Vespa Cosa models, since without exception a (too short) reduction of 21/68 was installed ex works. So every PX80/PX125 owner, who wants to drive a 177cc cylinder, can use a suitably long gear ratio by simply changing the clutch pinion. The reduction ratio is thus increased by a full 15%, which corresponds approximately to the same increase in top speed in km/h.