Transmission parts from Stefano Benelli rightly enjoy an excellent reputation in the racing scene. 
Anyone looking for reliable racing technology for their gearbox will find it here.
 
Hardened to an average of 60 HRC, Benelli parts offer exactly the right balance of hardness and elasticity to withstand the enormous stresses in a racing engine over the long term. 
Benelli offers a reinforced primary kit for Vespa Largeframe engines with wide primary gear (from around model year 1965 onwards).
This kit offers some special features:
Screwed cover plate = no riveting necessary!
Clutch gear for old PX type clutch (6/7 springs) = suitable for Kingwelle or Crimaz CMX clutches
The delivery includes the original primary springs of the PX200 models.
For powerful engines, we recommend reinforced primary springs that can cope with the high torque of a tuned engine. 
Unlike original springs, these no longer go solid. 
This means the springs do not compress fully and still provide sufficient travel. 
This prevents load peaks from being transferred into the gearbox and protects the components despite higher engine power. 
The primary kit is supplied ready to install and features a screwed reinforced cover plate for the primary springs.
 
The other side is closed, i.e. it has been machined from solid together with the gear.
ASSEMBLY NOTE
 
If the set is used in a Malossi engine casing (VR-One / V-One), the bearing seat of the large crankshaft bearing must be slightly relieved.
 
Otherwise the primary gear will touch the reinforced bearing seat of the Malossi casings.
| Primary gear 65 teeth | |||
| Primary pinion | 20 | 21 | 22 | 
| Ratio | 3.25 | 3.09 | 2.95 | 
| Primary gear 64 teeth | |||
| Primary pinion | 22 | 23 | 24 | 
| Ratio | 2.90 | 2.78 | 2.66 | 
| Primary gear 63 teeth | |||
| Primary pinion | 23 | 24 | 25 | 
| Ratio | 2.73 | 2.62 | 2.52 | 
| Primary gear 61 teeth | |||
| Primary pinion | 22 | 23 | 24 | 
| Ratio | 2.77 | 2.65 | 2.54 | 
| Primary gear 60 teeth | |||
| Primary pinion | 23 | 24 | 25 | 
| Ratio | 2.60 | 2.50 | 2.40 | 
(US)