Post by Mx Life286 on Sept 27, 2005 21:10:20 GMT -5
Q: HOW IS YOUR BODY LIKE A FOUR-STROKE ENGINE?
A: As you read this, your body is automatically combusting energy. The process is called metabolism, and it works like this: First, you breathe oxygen into your lungs. The hemoglobin in your red blood cells carries the oxygen to all the working cells in your body. Once in the cells, it is oxidized with the glucose (also transported by blood). Inside the cells, the glucose is broken down to carbon. The carbon combines with oxygen, and energy becomes available for use. The harder your body works, the quicker your breathing gets. And, the faster you breath, the faster the blood circulates (and the more energy the cells oxidize). Metabolizing energy creates carbon dioxide, which is released into the blood, circulated to the lungs and breathed out.
All Nicolaus had to do was duplicate the process with nuts and bolts.
Q: HOW DID NICKY OTTO DUPLICATE THE PROCESS WITH NUTS AND BOLTS?
A: It takes billions of human cells to produce one-sixth of a horsepower. Otto needed a lot more horsepower than that, so he designed one giant "cell" to metabolize energy. Otto built a mechanical pump that simulated the human body. In it, oxygen was combined with the carbon in gasoline and ignited under pressure. That is the way it's still being done to this day.
Q: WHY IS IT CALLED A FOUR-STROKE?
A: It is pretty obvious that four-strokes get their name because the piston strokes four times. It moves down, up, down and up to create one cycle of energy. Each time the piston moves from top dead center to bottom dead center (or vice-versa), it represents one stroke.
Here's a summary of all four strokes: (1) The first stroke brings fuel in. (2) The second stroke compresses and ignites it. (3) The third stroke releases the energy. (4) The fourth stroke expels the spent gas.
Q: WHAT IS THE FIRST STROKE OF A FOUR-STROKE ENGINE?
A: Using a piston, cylinder and valves, Otto was able to create a vacuum that drew air into the engine just as expanding lungs draw air into the human body. The first stroke of a four-stroke engine is called the "intake stroke."
Starting from top dead center (TDC), the crank rotates and draws the piston downward. As the piston moves down the intake valve, the cylinder head opens. The descending piston creates a vacuum inside the combustion chamber that sucks air from the carburetor into the head (via the intake valve's passage). As the air is being pulled through the carburetor, the vacuum also draws gasoline out of the carb's float bowl. The air and gas are mixed together as they are swept into the cylinder head.
By the time the piston reaches bottom dead center (BDC) of its first stroke, the cylinder head is filled with a fine vapor of gas and air.
The first stroke of a four-stroke engine is identical to the human body's lungs taking a deep breath and saturating glucose-rich blood with oxygen.
Q: WHY IS THE SECOND STROKE CALLED THE THE COMPRESSION STROKE?
A: Before a four-stroke engine's piston begins its second stroke (its return trip upward), the intake valve slams shut, trapping the gas/air vapor that was drawn in by the vacuum of the down stroke. The upward arc of the piston is the second stroke of a four-stroke engine. It is called the "compression stroke," because as the piston moves up, it shrinks the space between the top of the piston and the cylinder head. The gas/air mixture is compressed by the rapidly advancing piston.
For medical buffs, the compression stroke is similar to the human body splitting glucose into dual three-carbon compounds. The rupturing of glucose sets off a chain of chemical reactions that ultimately results in it being completely broken down into single-carbon fragments.
In a four-stroke engine, the second stroke compresses a volatile fuel mixture. Just before the piston reaches the top of its second stroke, the compressed fragments of oxygen and gasoline are ignited by the spark plug.
Q: WHAT DOES THE SPARK PLUG HAVE TO DO WITH THE THIRD STROKE?
A: When a four-stroke engine ignites the fuel mixture, it creates carbon monoxide. The expansion of the burning gas produces enough freed energy to violently shoot the piston back on its second journey downward.
This is the third stroke of a four-stroke engine. The downward motion of the piston, caused by the expansion of burning fuel, releases enough energy to spin the crank two complete revolutions (essentially move the piston up and down twice--at which point it gets hit by the next release of energy).
In the human cell, the carbon formed by the splitting of the glucose combines with oxygen to form carbon dioxide. By combining the fragments with oxygen, it's possible for the human cell to combust (metabolize) energy. Carbon dioxide is the human body's version of a four-stroke engine's carbon monoxide.
Q: WHAT'S THE FOURTH STROKE OF A FOUR-STROKE?
A: As the force of combustion pushes the piston down, the crank spins past bottom dead center and redirects the piston upward on its fourth trip. As the piston starts back up, it pressurizes the combustion chamber for the second time. This time, the exhaust valve opens as the piston closes in. The increasing pressure pushes the burnt gas and air out of the exhaust valve through the exhaust pipe. It is called the "exhaust stroke." This is the fourth stroke that the piston has made since receiving that first fresh shot of fuel.
In human terms, the excess carbon dioxide that isn't used for energy is released into the blood, circulated to the lungs and breathed out.
Q: WHAT MOVES THE INTAKE AND EXHAUST VALVES?
A: In simple terms, the movement of the piston moves the valves. There is a gear on the crankshaft that drives a chain (or belt) that spins a cam inside the cylinder head. The lobes on the cams push the valves open (springs close them).
Q: HOW DO THE VALVES KNOW WHEN TO OPEN?
A: Since the position of the piston is known by how far the crank has rotated, it's possible to time the cam lobes to push the intake and exhaust valves to open at the prescribed moments. On many old-style engines and on one-half of the CRF valve train, rocker arms work like seesaws to communicate the shape of the cam lobes to the valve. As the cam lobe contacts one end of the rocker arm, it is pushed upward off the fulcrum. The opposite end of the rocker arm pushes downward and opens the valve into the cylinder head. Since they are spring loaded, the valves automatically snap shut when the cam lobe rotates past the rocker arm.
The YZ-F, KX-F, RM-Z and intake valves of the CRF don't have rocker arms. Instead, they use "buckets." These buckets, which are cylindrical in shape, ride directly between the cam lobe and valve stem. As the lobes rise and fall, the buckets activate the valves. To do both the intake and exhaust valves requires two cams (thus the phrase--dual overhead cams).
Q: IS IT A FOUR-STROKE OR A FOUR-CYCLE ENGINE?
A: It's incorrect to call a four-stroke engine a "four cycle engine." A four-stroke gets its name because it takes four strokes of the piston and two full revolutions of the crank to complete one combustion cycle. By comparison, a two-stroke engine completes one full combustion cycle with only two strokes of the piston (up and down) and one full revolution of the crank. Thus a two-stroke is a one cycle engine, and a four-stroke is a two-cycle engine.
A: As you read this, your body is automatically combusting energy. The process is called metabolism, and it works like this: First, you breathe oxygen into your lungs. The hemoglobin in your red blood cells carries the oxygen to all the working cells in your body. Once in the cells, it is oxidized with the glucose (also transported by blood). Inside the cells, the glucose is broken down to carbon. The carbon combines with oxygen, and energy becomes available for use. The harder your body works, the quicker your breathing gets. And, the faster you breath, the faster the blood circulates (and the more energy the cells oxidize). Metabolizing energy creates carbon dioxide, which is released into the blood, circulated to the lungs and breathed out.
All Nicolaus had to do was duplicate the process with nuts and bolts.
Q: HOW DID NICKY OTTO DUPLICATE THE PROCESS WITH NUTS AND BOLTS?
A: It takes billions of human cells to produce one-sixth of a horsepower. Otto needed a lot more horsepower than that, so he designed one giant "cell" to metabolize energy. Otto built a mechanical pump that simulated the human body. In it, oxygen was combined with the carbon in gasoline and ignited under pressure. That is the way it's still being done to this day.
Q: WHY IS IT CALLED A FOUR-STROKE?
A: It is pretty obvious that four-strokes get their name because the piston strokes four times. It moves down, up, down and up to create one cycle of energy. Each time the piston moves from top dead center to bottom dead center (or vice-versa), it represents one stroke.
Here's a summary of all four strokes: (1) The first stroke brings fuel in. (2) The second stroke compresses and ignites it. (3) The third stroke releases the energy. (4) The fourth stroke expels the spent gas.
Q: WHAT IS THE FIRST STROKE OF A FOUR-STROKE ENGINE?
A: Using a piston, cylinder and valves, Otto was able to create a vacuum that drew air into the engine just as expanding lungs draw air into the human body. The first stroke of a four-stroke engine is called the "intake stroke."
Starting from top dead center (TDC), the crank rotates and draws the piston downward. As the piston moves down the intake valve, the cylinder head opens. The descending piston creates a vacuum inside the combustion chamber that sucks air from the carburetor into the head (via the intake valve's passage). As the air is being pulled through the carburetor, the vacuum also draws gasoline out of the carb's float bowl. The air and gas are mixed together as they are swept into the cylinder head.
By the time the piston reaches bottom dead center (BDC) of its first stroke, the cylinder head is filled with a fine vapor of gas and air.
The first stroke of a four-stroke engine is identical to the human body's lungs taking a deep breath and saturating glucose-rich blood with oxygen.
Q: WHY IS THE SECOND STROKE CALLED THE THE COMPRESSION STROKE?
A: Before a four-stroke engine's piston begins its second stroke (its return trip upward), the intake valve slams shut, trapping the gas/air vapor that was drawn in by the vacuum of the down stroke. The upward arc of the piston is the second stroke of a four-stroke engine. It is called the "compression stroke," because as the piston moves up, it shrinks the space between the top of the piston and the cylinder head. The gas/air mixture is compressed by the rapidly advancing piston.
For medical buffs, the compression stroke is similar to the human body splitting glucose into dual three-carbon compounds. The rupturing of glucose sets off a chain of chemical reactions that ultimately results in it being completely broken down into single-carbon fragments.
In a four-stroke engine, the second stroke compresses a volatile fuel mixture. Just before the piston reaches the top of its second stroke, the compressed fragments of oxygen and gasoline are ignited by the spark plug.
Q: WHAT DOES THE SPARK PLUG HAVE TO DO WITH THE THIRD STROKE?
A: When a four-stroke engine ignites the fuel mixture, it creates carbon monoxide. The expansion of the burning gas produces enough freed energy to violently shoot the piston back on its second journey downward.
This is the third stroke of a four-stroke engine. The downward motion of the piston, caused by the expansion of burning fuel, releases enough energy to spin the crank two complete revolutions (essentially move the piston up and down twice--at which point it gets hit by the next release of energy).
In the human cell, the carbon formed by the splitting of the glucose combines with oxygen to form carbon dioxide. By combining the fragments with oxygen, it's possible for the human cell to combust (metabolize) energy. Carbon dioxide is the human body's version of a four-stroke engine's carbon monoxide.
Q: WHAT'S THE FOURTH STROKE OF A FOUR-STROKE?
A: As the force of combustion pushes the piston down, the crank spins past bottom dead center and redirects the piston upward on its fourth trip. As the piston starts back up, it pressurizes the combustion chamber for the second time. This time, the exhaust valve opens as the piston closes in. The increasing pressure pushes the burnt gas and air out of the exhaust valve through the exhaust pipe. It is called the "exhaust stroke." This is the fourth stroke that the piston has made since receiving that first fresh shot of fuel.
In human terms, the excess carbon dioxide that isn't used for energy is released into the blood, circulated to the lungs and breathed out.
Q: WHAT MOVES THE INTAKE AND EXHAUST VALVES?
A: In simple terms, the movement of the piston moves the valves. There is a gear on the crankshaft that drives a chain (or belt) that spins a cam inside the cylinder head. The lobes on the cams push the valves open (springs close them).
Q: HOW DO THE VALVES KNOW WHEN TO OPEN?
A: Since the position of the piston is known by how far the crank has rotated, it's possible to time the cam lobes to push the intake and exhaust valves to open at the prescribed moments. On many old-style engines and on one-half of the CRF valve train, rocker arms work like seesaws to communicate the shape of the cam lobes to the valve. As the cam lobe contacts one end of the rocker arm, it is pushed upward off the fulcrum. The opposite end of the rocker arm pushes downward and opens the valve into the cylinder head. Since they are spring loaded, the valves automatically snap shut when the cam lobe rotates past the rocker arm.
The YZ-F, KX-F, RM-Z and intake valves of the CRF don't have rocker arms. Instead, they use "buckets." These buckets, which are cylindrical in shape, ride directly between the cam lobe and valve stem. As the lobes rise and fall, the buckets activate the valves. To do both the intake and exhaust valves requires two cams (thus the phrase--dual overhead cams).
Q: IS IT A FOUR-STROKE OR A FOUR-CYCLE ENGINE?
A: It's incorrect to call a four-stroke engine a "four cycle engine." A four-stroke gets its name because it takes four strokes of the piston and two full revolutions of the crank to complete one combustion cycle. By comparison, a two-stroke engine completes one full combustion cycle with only two strokes of the piston (up and down) and one full revolution of the crank. Thus a two-stroke is a one cycle engine, and a four-stroke is a two-cycle engine.