How A Vespa Engine Works

If you are the owner of a Vespa, you have probably wondered how a Vespa engine works. The workings of a Vespa engine are actually quite simple. The following guide will help you learn how a Vespa engine works.

To learn how a Vespa engine works, you will need:

  • Access to a Vespa engine (optional)
  • A diagram of a Vespa engine (optional)


  1. There are three main components to a Vespa engine: the crank shaft, lay shaft, and transmission gears. The crank shaft and main bearings are the first of the three parts. This is where the piston is attached.
  2. Beside the crank shaft is the lay shaft, which is stationary and has a series of gears that gradually decrease in size. These gears move around the lay shaft and match up with the gears of the four speed transmission. The four speed gears also gradually decrease in size.
  3. The transmission shaft is directly connected to the back wheel of the Vespa.
  4. The kick starter on the Vespa engine forces the gears on the lay shaft to move, which in turn causes the gears of the crank shaft and transmission to move as well. Once the Vespa engine can sustain its own motion it no longer needs the kick starter and the piston begins moving on its own.
  5. The plunger is connected to the transmission gears and controls how fast the Vespa engine is moving. The farther inward the plunger is pushed, the faster the Vespa engine is able to move.
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