Malossi Primary Gear Up Install - Aprilia SR50R / Piaggio Engine

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In this video I show how to upgrade the primary gears on an Aprilia SR50R.
As the SR50R shares its Piaggio Hiper2 base engine with many models of different scooters these instructions can be used as a guide for virtually all Piaggio, Vespa and Aprilia 50cc 2T models made since 1999 as well.

The only significant difference in the different models are the number of teeth, which accommodate for the different wheel sizes. As a 10" wheel has a smaller circumference than a 13" wheel, they travel different distances per rotation. Always count your factory teeth before ordering a gear up kit! To achieve more top speed gearing, you need to reduce the different between the first and second gear of the kit.

I recommend calculating the final drive ratio first, then substituting different gearing kits that are available into the calculation to see what difference will be made.

The calculation is worked out:

(Big primary gear ÷ Small primary gear) x (Big secondary gear ÷ Small secondary gear)