Complete PIAGGIO main shaft set suitable for Vespa PX from 1984 onwards
Consisting of the following components
The main shaft set is supplied loose. The shoulder rings are positioned on the first and fourth gear. The shift cross/shift bolt has a left-hand thread. We recommend applying a drop of screw adhesive to the thread to mount the shift bolt. The gears are manufactured asymmetrically and can only be operated in one installation position.
TIP: The easiest way is to install the main shaft in the engine block and then mount the gears in the same alignment with the splines of the auxiliary shaft. This allows you to see immediately whether the gearwheel is installed the right way round.
The original Piaggio gearboxes are available in three versions:
58, 42, 38, 36 teeth - original PX125 gradation
57, 42, 38, 36 teeth - like PX125, but with the long first gear of the PX200
57, 42, 38, 35 teeth - original PX200 gradation
We always recommend the version with 35 teeth (gear 4) for heavily tuned engines. This is more stable than the 125cc version with 36 teeth. However, if a shorter jump from gear 3 to gear 4 is desired/necessary, we recommend the use of a secondary shaft with 20 instead of 21 teeth (e.g. BGM6506). In this combination (20/35T = 1.75), the gear pairing for fourth gear is designed for maximum stability.
In our experience, the variant with 36 teeth in conjunction with the standard auxiliary shaft (21/36 = 1.71) can be used permanently for engines up to approx. 15-20 hp.
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