Scooters with 49cc or 50cc engines are among the most popular on the market for one simple reason: In many states, riders are not required to have a motorcycle license to drive them--a regular driver's license is all you need.
The difference between a 49cc and 50cc engine is just one cubic centimeter of displacement. Some scooters marketed and sold as having 50cc engines may actually have 49cc engines, and you can bore out the cylinders on a scooter engine by 1cc or 2cc when reringing the pistons to make a worn engine run as if new again.
Engine power
Cubic centimeters, abbreviated cc, is one way to measure the power of an engine. It is the unit of measurement used to describe the volume in the engine's firing cylinders displaced by the pistons, which is why it is also referred to as engine displacement.
Two-stroke vs. four-stroke
A 49cc or 50cc engine is often a two-stroke engine, which means the engine cycle lasts two strokes of the piston. In a two-stroke engine, the oil and gas are mixed in the engine pistons to power the scooter.
Modern 49cc or 50cc engines are often four-stroke, which means the piston goes through four strokes before the firing sequence starts again. Four-stroke scooter engines burn only gas, while the oil lubricates the crankcase.
Displacement difference
Whether two-stroke or four-stroke, the main difference between a 49cc and 50cc scooter engine is the displacement or volume in the cylinder covered by the piston. Increasing the volume a piston can cover in the cylinder can increase compression and therefore the engine's power.
Engine cc identification
Some scooters marketed and sold as having 50cc engines may actually have 49cc engines. To learn the actual displacement of your scooter engine, look under "specifications" in your owner's manual, or look on your engine block. This may require you to take body panels off your scooter.
If you do not have the owner's manual for your make and model of scooter, contact your scooter manufacturer.
Honing/boring
You can bore out the cylinders on a scooter engine by 1cc or 2cc when reringing the pistons to make a worn engine run as if new again. Some scooter owners bore out the pistons to increase the cc and gain increased horsepower.