The 2 stroke engines in our R/C cars work just the same as the engines in leaf blowers or weed wackers. With a 2 stroke, the engine creates power for every full revolution of the crankshaft (crank). This is unlike 4 strokes, which make power for every 2 turns of the crank. This means that a 2 stroke can make twice the power of a 4 stroke that is the same size. This is very benifical to our R/C cars, because their engines need to make as much power as possible without weighing alot.
A 2 stroke, just like the name says, consits of 2 strokes. A stroke is when the piston inside the motor travels from the top to the bottom of the engine, or vice-versa. When the piston reaches the top of the crankcase, it compresses the air/fuel mixture, and the glow plug causes the compressed air/fuel to explode. this shoves the piston down, and starts the first stroke. the ports for the air/exhaust to flow out/into the cylnder are drilled into piston sleeve. the sleeve is the cylinder around the piston, and the pinton travels up and down in it. when the piston gets near the bottom of the crankcase, the exhaust and intake ports are exposed. the exhaust then flows out, and the mixed air/fuel in. as the piston travels up, the intake port is covered first, alowing the rest of the exhaust to be pushed out by the air/fuel. This is why alittle gas comes out of the exhaust pipe, this process causes alittle of the air/fuel to go out the exhaust port with the exhaust gases. this is also the reason as to why 4 strokes get better gas mileage than 2 strokes. the piston covers the exhaust port as it travels up. when it reaces the top, it compresses the air/fuel and the air/fuel explodes, and the whole process starts over. the 2 stroke process involves few moveing parts. this is why 2 strokes can rev very high (our R/C engines get to 35,000 rpm). The only reason 4 strokes cant do that is because of the many moveing parts.
Tuned pipes are very important for the 2 strokes in our R/C cars. When the intake and exhaust ports are open at the same time, some of the air/fuel mixture is allowed to exit out the exhaust port. A tuned pipe takes the pressure waves that the engine creates, and shoots them back at the exhaust port, pushing the unburnt air/fuel mixture back into the engine. This is why just a tuned pipe alone can cause your engine to make alot more power. There are also adjustable tuned pipes. they bacially allow you to change when the pressure waves are shot back. by moveing the clip away from the motor, you allow more power to be made at high rpms, which means more speed. By moveing the clip toward the engine, the pressure waves get to the engine sooner, causeing there to be more low rpm torque, but less high rpm power.
I hope you lerned alot! the way I said a 2 stroke works applys to all 2 stroke engines, so I hope you take this knowldge with you in life. Just rember a Tuned pipe that makes more torque is better for short tracks, and ones that make more horsepower/high rpm power is good for long tracks with straight a ways.