Kits are great for increasing your power or capacity, but the Vespa/Lambretta engine has been left far behind in relation to motorcycle barrels.

Motorcycles have been using two stroke engines for ages and the engines have advanced slowly but surely each year. By the mid 80s most production two stroke street and off-road bikes and ATVs were water cooled, had reed valve intakes, and were starting to venture into ignition timing and exhaust valve technology. These changes are beyond the limits of most scooter barrels, and suddenly allowed a huge amount of power to be created. 250cc bikes were starting to creep into the 40 horsepower range, 200s were into the 30s and the 125cc bikes were anywhere from 15-30 hp. Below is a list of two stroke cylinders that may be good candidates to engineer on to a scooter. I have yet to see a working cylinder based power valve on a scooter but I am working on a Lambretta cased Kawasaki combo that I will update as the project progresses. The existing stroke of the scooter you are trying to convert is typically a good start for a conversion. These are typical crankshaft strokes for Italian scooters:

• 51mm Small frame Vespa
• 57mm Large frame Vespa
• 58mm Lambretta
• 60mm Long stroke Vespa

Any crankshaft that is successfuly matched to a motorcycle barrel will have to be very strong and should have the con rod replaced so I have only listed the biggest capacity scooter cranks and ones that tougher full circle cranks (or even welded crank pins) are available or adaptable for. Wherever possible I have added links to pages & visuals on the cylinder and a history of cylinder changes throughout the model run. Most bikes were sadly not available in the USA but cyclinders are sometimes available. I hope this helps to create some fast scooters!

 

* notes twin or multiple cylinder bikes, but each cylinder is independently cast.