[Nitro]

The goal is to spin the rear wheel.

The mean is a fast oxidization known as combustion, a form of explosion.

For this to happen you need a fuel (carbon-hydrogen chains), a mixer (oxygen), and a catalizer (spark plug for gas, heat for Diesel).

You use Boyle's Law: PV=nRT

So you compress the oxygen, squirt fuel, burn the s h i t out of it, and repeat.

The final motion is rotatory (the wheel) so you convert the oscillatory motion of the pistons via the connecting rods and counter shaft.

Attach your clutch, tranny, final drive and done you are.

The more oxygen you can burn the more fuel you can burn as simple as that.

The more you burn the more usable power is generated and ultimately torque measured (the wheel spinning).

At sea level you got about 21% of oxygen in the air.

The higher you go, the less the pressure, molecules spread apart and slow down (entropy) and thus per volume of air, eventually there's not enough oxygen to burn.

So you add an air compressor driven by the force of the exhaust gases (turbo-compressor) or via a belt, gear, or chain (supercharger).

Now you are compressing air before it enters the combustion chamber; more air more fuel more of just more.

The bigger the piston, the more air you can suck and compress; the more air the more fuel the more awesomeness.

If you go too big with the piston, it becomes an inertia issue; the engine won't spin too high. Airplanes engines use this principles to produce large amount of torque via huge displacement at the expenses of high RPM. This works out because you can attach a propeller right on the flywheel and be still at subsonic speeds at the propeller's wingtips @ full power.

More pistons for the same displacement = smaller pistons = higher RPM.

More pistons = more explosions = less traction.

Keep things simple with motorcycles: 1 piston for dirt, 2 pistons for street.

You can two-stoke it or four stroke it. Honda had strong convictions towards the four-stroke; I am not so sure.

Nowadays a 4-stroke can spin almost as fast as two-stroke of same displacement.

Two stroke = more explosions per RPM = more of more.

Two stokes are simpler systems.

Four-stroke valve actuation is accomplished via different methods: Direct cams, cams and rockers, cams and lifters actuated via hydraulics, gear, chain, belt, or levers. There are excellent examples of all of them and not so excellent of all of them.

We are combining oxygen and nitrogen with hydrocarbons yielding water, CO2, CO, NO2, NO, heat, entropy, and more.

Burn, burn, burn because one day you ain't gonna burn nothing no more.