1. Designed to be inexpensive and simple to build and maintain, the 1952 Power Free had a 36 cc, one horsepower, two-stroke engine.

2. According to Achates Power, its opposed-piston, two-stroke engine has demonstrated an increase in fuel efficiency and similar engine-out emissions levels.

3. In a piston-cylinder assembly of an internal combustion engine, especially a two-stroke engine, at least the piston-sliding surface of the cylinder is made of an aluminium alloy.

4. The engine is an air-cooled, parallel twin, six-speed (in some markets, such as the UK, the first model was sold in five-speed form), reed valve-equipped intake tract two-stroke engine.

5. In a two-stroke engine, the Camshaft rotates at the same speed as the crankshaft, while in a four-stroke engine, the Camshaft spins at half the speed of the crankshaft since the Camshaft gear has

6. The working range of the fuel screw on a four-stroke engine is one to three half-turns out, while the Airscrew on a two-stroke engine has a working range of one-and-a-quarter to two half-turns out.