Wednesday 10 June 2015
defeat
The ignition coil and stator coil can both be tested using an ohm meter, to determine whether or not they are providing the proper amount of resistance, and receiving the proper voltage. Ohm meters are expensive and I don't have one, plus I don't know how to use one. The CDI box can't be tested with an ohm meter, and must be sent into a shop to be tested, which obliviously costs money. I'm not sure how to test these components without spending a lot of money, and apparently the part testing ok, doesn't necessarily mean the part is ok. My friend Jeremy also has a 450 sport quad, so we decided to try the ignition coil off of it. The bike started up as normal, and ran after 20 minutes of running (about double what it did before) I was certain we had solved the problem. To my great dismay, at about 25 minutes, the motor died, refusing to spark just as before. While disappointing this leads me to believe that the CDI box is to blame. Unfortunately while running it for those 20 minutes and a brief ride, a far more serious mechanical problem emerged. For seemingly no reason the bikes transmission wouldn't want to change gears, and made disturbing noises when I tried. I feel like the previous owner must have abused the clutch and transmission, because I have always used the clutch properly, never bump shifting or abusing the transmission. I'm terrified by this recent discovery, and have decided not ride the quad, or run it outside of neutral until I have had a chance to investigate further. I'm hoping the issue clutch related, not transmission related. If the problem is the clutch, it shouldn't be insanely expensive, and I should be able to do the work myself. However if the issue is transmission related, I could be screwed. The sequential transmissions of a motocross motors are extremely complicated, and are not actually bolted to the motor, instead the are pretty much part of the motor, the gears are inside the crankcase. I haven't had a chance to do any research but im pretty sure that these sequential gearboxes have three shafts of gears that are manipulated by shift forks, causing them mesh in different gear ratios, honestly I'm not sure. If there was transmission damage,I would not have the skills to fully disassemble the motor to fix it, and the parts would be very expensive. I really hope the transmission isn't broken, because if it is I would have to send it to a shop, and pay money I don't have. Well throughout the course of this project I didn't fix anything and things got worse. While there is no doubt I failed my first goal, I did manage to achieve my smaller secondary goals.
Learning 2
If you have been reading my posts your probably thinking that I haven't got anything done, which isn't exactly true. While I've made a disappointing amount of progress on solving my quads mysterious problem, this project hasn't been a true failure. My goal wasn't just to fix this quad, it was to learn about internal combustion motors, how they work, and how to service them. Throughout the course of this project I have learned a lot about motors, all the understanding I showed in previous posts was a direct result result of prior research. To demonstrated what I've learned I'll just explain in a very basic way, how internal combustion engines work.
Internal combustion engines use one or more pistons to turn a crankshaft. The piston harnesses the energy of expanding gasses in the combustion chamber, using them to to turn the crank shaft. The cylinder is a sleeve of sorts that the piston reciprocates inside of, there are several types of motors that are named based on the configuration of their cylinders.
Two stroke or four stroke, what's the difference.
The stroke, or cycle refers to how many strokes the piston takes per one combustion.
Two stroke motors are the simpler of the two motors, there are only 2 piston strokes, and they usually require oil to be mixed with the fuel in order to lubricate the cylinder.
As the piston moves up it compresses the air fuel mixture in the cylinder, when the piston is at the top of its stroke the spark plug ignites the mixture, forcing the piston down in a combustion stroke. As the piston moves down, it passes an exhaust port near the middle of the cylinder, and exhaust gasses are let out. The piston continues moving down past an intake port at the bottom of the stroke, drawing air into the cylinder. The air is compressed, ignited and the the cycle continues. to give you a better understanding, here is a link to a YouTube video of a two stroke animation. http://motocrossactionmag.com/bike-tests/ktm-tests/everything-you-need-to-know-about-the-all-new-ktm-factory-edition-iv
This primitive diagram shows a cut away of a two stroke cylinder.
Four stroke motors are more complex than two strokes, have more moving parts, and are more difficult work on. Four strokes are able to lubricate there cylinders, eliminating the need to mix oil in the gas. there are 4 piston strokes in a four stroke. As the piston moves up it compresses the air fuel mixture in the cylinder (compression) when fully compressed the spark plug ignites the mixture, forcing the piston down (combustion). As the piston moves back up, an exhaust valve(s) open and the exhaust gasses are released (exhaust). The piston moves back down, and the intake valves open, allowing fresh air and fuel into the cylinder (intake). My Polaris is a four stroke. To give you a better idea, here is a link to a YouTube video of a four stroke animation. https://www.youtube.com/watch?v=2Yx32F1cncg
This primitive diagram shows a cut away of a four stroke cylinder.
Two strokes have twice as frequent combustion strokes, compared to four strokes. This allows the engine to rev higher, and produce significantly more power than a four stroke in the same displacement. Two strokes are cheaper to make, and easier to service. Two strokes are very inefficient, and burn more fuel than four strokes, as well as burning oil in the gas, which creates a whitish blue exhaust gasses that are very harmful for the environment. A two stroke also has a large bloated header called an expansion chamber, that gives the exhaust gas extra room before it flows to the exhaust Two strokes have a distinct tinging sound that some people love, and some people hate. Two strokes may be able to produce a lot of power, but the power is created in an unpredictable, (hard to control) way, with power violently peaking at high RPM. Because two strokes make more power in a smaller displacement than four strokes, they have a smaller displacement limit in motocross race classes. 125cc two stroke race with 250cc four strokes, and 250cc two strokes race with 450cc four strokes. Two strokes are less common than four strokes, and are usually only used in dirt bikes, snowmobiles and small single cylinder utility tools such as chain saws,or weed trimmers.
Four strokes may have a less frequent combustion stroke, but they are far more efficient, producing more power, and significantly more torque at lower RPM. Four stroke create power in a much more linear way than two strokes, which makes the power easier to use and control. Because four stokes have less power strokes, however the power strokes harness the energy more efficiently, less power strokes means the motor burns considerably less fuel as well. Because four strokes don't burn oil, they're exhaust gasses are significantly less harmful to the environment. Because two strokes make more power in a smaller displacement than four strokes, they have a smaller displacement limit in motocross race classes. 125cc two stroke race with 250cc four strokes, and 250cc two strokes race with 450cc four strokes. Modern Four stroke motocross engines are extremely powerful, and have been dominating the smaller two strokes in racing. For example, a modern 125cc two stroke has about 33 horse power while a 250cc four stroke has about 38 horse power and significantly more torque. Four strokes are extremely common and are used in all cars and trucks. My Polaris is a four stroke, Polaris chose to use a four stroke because it makes much more torque and power at low RPM than a two stroke. The low-end power and torque are much more useful in a heavier quad than in a light dirt bike.
This picture shows the intake valves (right) and exaust valves (left) on my quad.
In this vague exaggerated dyno graph the dotted line represents a 125 two stroke while the solid line represents a 250 four stroke. As you can see the four stroke makes more power at lower RPM, and consistently climbs to its max power. The two stroke makes much less power at low RPM, before it hits its (power band) at higher RPM where power rapidly increases. This rapid transition from low power to high power makes two strokes more difficult to control.
All motors get very hot while running, The heat is a product of the combustion process. Obviously igniting gasoline creates a great deal of heat, in fact up to 60-80 percent or more of the total energy a motor produces is thermal energy in the from of unwanted heat. This heat, if not dissipated, will cause parts of the motor to deform and break.
There are three ways a motor is cooled.
The most primitive way is air cooling. Air cooled motors simply have fins on the cylinder that increase the cylinders external surface area, allowing the colder outer air two cool the fins, and cylinder. Air cooled motors, can be very reliable, as there is no liquid cooling system to break. Usually only small motors are air cooled such as chain saws, or motorcycles. Air cooling is not as effective as the other options, as a result the motor usually cant be pushed as hard.
The most common way a multi-cylinder motor is cooled is liquid cooling. In a liquid cooled motor, water or coolant is circulated through channels in the cylinder by a water pump that is usually driven by the motor. The water absorbs the heat from the cylinder and is pumped to the radiator, which has hundreds of tiny fins on the outside, and many grooves on the outside. The large surface area of these fins cools the water in the same way that the fins on a air cooled motor cool the cylinder. Liquid cooling is far more effective, because liquid transfers heat much better, than air, and the circulating liquid allows for faster cooling. Essentially all performance motors use liquid cooling because it allows the motor to run harder for longer. All new cars and trucks use liquid cooling, because the motor is inside an enclosed engine bay where fresh cold outside air can not circulate to cool the cylinders of an air cooled motor, also air cooling only works on motors with separated cylinders, while the cylinders in all new cars are in engine blocks.
Oil cooling is usually only found in performance motors. Unlike the first two cooling systems, oil cooling does not cool the cylinder. As a result oil cooling has to be paired with a cylinder cooling system, (pretty much always liquid cooling). Oil cooling cools the oil, using a device similar to a radiator, that the existing oil pump circulates the oil to. Cooled motor oil cools the bottom end of the motor, as well as all the parts it lubricates, There are two types of oil cooling, motor oil cooling, and transmission oil cooling. The motor oil mainly cools the bottom end of the motor, while the transmission fluid (oil) cools the gears in side a transmission. some industrial vehicles also have differential cooling, which is identical to transmission cooling.
And in case you didn't know, the differential splits power between the pairs of wheels while turning, taking power away from the inner wheel to allowing the outer wheel to turn at a faster rate than the inner wheel, resulting in easier turning, and no loss of traction. My quad has a solid rear axle and no differential. This means that in order to turn, the inside back wheel must break free and lose traction. Because of this the only way to effectively turn is to slide/drift which is awesome.
A transmission or gear box allows multiple graduated gears to be selected, this allows the vehicle to put as much power or tourque to the wheels at a given speed as possible. The gears are graduated, the gears start off low, allowing the motor to turn the wheels at a rate more closer to the motor rate, this allows for much faster acceleration, however, the motor will reach max RPM very quickly, and at a low speed, at this poin you simply shift into the next slightly higher gear and the process repeats itself. Gear boxes are very complicated and I won't explain them. Manual car transmissions are shifted by your hand on a stick, that must be placed in the correct shift spot or gate to select a gear. Motorcycle and quad transmissions are operated by a toe actuated shift lever on the left side of the bike. Unlike car transmissions, bike transmissions are sequential meaning you simply bump the shift lever up to shift up, and down to shift down.
A clutch is another incredibly important part of almost all motorized creations. The clutch transfers power form the motor to the gear box, and can be disengaged to allow for shifting. Clutches are found in many pieces of machinery. The most basic type of clutch would be the type of clutch a weed wacker or chainsaw has. These clutches are centrifugal clutches. The clutch uses springs to keep itself disengaged at low RPM allowing the motor to turn without engaging the implement. At higher RPM the centrifugal force on the clutch increases, overpowering the springs and allowing it to engage two friction plates, sending power to the implement (spinning the weed wacker, or turning the chainsaw chain). The clutches in manual cars are very different, and are manually operated. Naturally the clutch is engaged, and the clutch pedal must be depressed to disengage the clutch (separating the two friction plates). Without neutral, or a clutch, no vehicle, could really start, or be drive-able, because the wheels would always spin with the motor, meaning you could never stop without the motor dying, and starting would require enough force to move the car. The clutches found on motorcycles, dirt bikes and quads have multiple friction plates not just two. This is because the plates have to be much smaller, to fit in a small space on the side of the motor, a space where car sized friction plates could never fit. In order to make the clutch strong and prevent clutch slippage despite the small friction plates, multiple plates are used (my quad has 8 I think). the increased number of plates not only increases clutch friction, but makes the clutch significantly easier to disengage, which is very necessary consider you use a finger lever to disengage the clutch. To get a better understanding, heres a YouTube video of a clutch animation. https://www.youtube.com/watch?v=TcYsV063lk8
Internal combustion engines use one or more pistons to turn a crankshaft. The piston harnesses the energy of expanding gasses in the combustion chamber, using them to to turn the crank shaft. The cylinder is a sleeve of sorts that the piston reciprocates inside of, there are several types of motors that are named based on the configuration of their cylinders.
These primitive drawings show common engine configurations. Despite the poor drawing, the cylinders, line of v motors are parallel to each, the v represts the angle the cylinders come out of the motor at.
The cylinders in most motors with three or more cylinder are bored from one piece of metal, called the engine block. The pistons, cylinder, valves, cam shafts etc, are known as the top end, while the crank shaft, connecting rods, engine casings etc are known as the bottom end.Two stroke or four stroke, what's the difference.
The stroke, or cycle refers to how many strokes the piston takes per one combustion.
Two stroke motors are the simpler of the two motors, there are only 2 piston strokes, and they usually require oil to be mixed with the fuel in order to lubricate the cylinder.
As the piston moves up it compresses the air fuel mixture in the cylinder, when the piston is at the top of its stroke the spark plug ignites the mixture, forcing the piston down in a combustion stroke. As the piston moves down, it passes an exhaust port near the middle of the cylinder, and exhaust gasses are let out. The piston continues moving down past an intake port at the bottom of the stroke, drawing air into the cylinder. The air is compressed, ignited and the the cycle continues. to give you a better understanding, here is a link to a YouTube video of a two stroke animation. http://motocrossactionmag.com/bike-tests/ktm-tests/everything-you-need-to-know-about-the-all-new-ktm-factory-edition-iv
Four stroke motors are more complex than two strokes, have more moving parts, and are more difficult work on. Four strokes are able to lubricate there cylinders, eliminating the need to mix oil in the gas. there are 4 piston strokes in a four stroke. As the piston moves up it compresses the air fuel mixture in the cylinder (compression) when fully compressed the spark plug ignites the mixture, forcing the piston down (combustion). As the piston moves back up, an exhaust valve(s) open and the exhaust gasses are released (exhaust). The piston moves back down, and the intake valves open, allowing fresh air and fuel into the cylinder (intake). My Polaris is a four stroke. To give you a better idea, here is a link to a YouTube video of a four stroke animation. https://www.youtube.com/watch?v=2Yx32F1cncg
Two strokes have twice as frequent combustion strokes, compared to four strokes. This allows the engine to rev higher, and produce significantly more power than a four stroke in the same displacement. Two strokes are cheaper to make, and easier to service. Two strokes are very inefficient, and burn more fuel than four strokes, as well as burning oil in the gas, which creates a whitish blue exhaust gasses that are very harmful for the environment. A two stroke also has a large bloated header called an expansion chamber, that gives the exhaust gas extra room before it flows to the exhaust Two strokes have a distinct tinging sound that some people love, and some people hate. Two strokes may be able to produce a lot of power, but the power is created in an unpredictable, (hard to control) way, with power violently peaking at high RPM. Because two strokes make more power in a smaller displacement than four strokes, they have a smaller displacement limit in motocross race classes. 125cc two stroke race with 250cc four strokes, and 250cc two strokes race with 450cc four strokes. Two strokes are less common than four strokes, and are usually only used in dirt bikes, snowmobiles and small single cylinder utility tools such as chain saws,or weed trimmers.
Four strokes may have a less frequent combustion stroke, but they are far more efficient, producing more power, and significantly more torque at lower RPM. Four stroke create power in a much more linear way than two strokes, which makes the power easier to use and control. Because four stokes have less power strokes, however the power strokes harness the energy more efficiently, less power strokes means the motor burns considerably less fuel as well. Because four strokes don't burn oil, they're exhaust gasses are significantly less harmful to the environment. Because two strokes make more power in a smaller displacement than four strokes, they have a smaller displacement limit in motocross race classes. 125cc two stroke race with 250cc four strokes, and 250cc two strokes race with 450cc four strokes. Modern Four stroke motocross engines are extremely powerful, and have been dominating the smaller two strokes in racing. For example, a modern 125cc two stroke has about 33 horse power while a 250cc four stroke has about 38 horse power and significantly more torque. Four strokes are extremely common and are used in all cars and trucks. My Polaris is a four stroke, Polaris chose to use a four stroke because it makes much more torque and power at low RPM than a two stroke. The low-end power and torque are much more useful in a heavier quad than in a light dirt bike.
All motors get very hot while running, The heat is a product of the combustion process. Obviously igniting gasoline creates a great deal of heat, in fact up to 60-80 percent or more of the total energy a motor produces is thermal energy in the from of unwanted heat. This heat, if not dissipated, will cause parts of the motor to deform and break.
There are three ways a motor is cooled.
The most primitive way is air cooling. Air cooled motors simply have fins on the cylinder that increase the cylinders external surface area, allowing the colder outer air two cool the fins, and cylinder. Air cooled motors, can be very reliable, as there is no liquid cooling system to break. Usually only small motors are air cooled such as chain saws, or motorcycles. Air cooling is not as effective as the other options, as a result the motor usually cant be pushed as hard.
The most common way a multi-cylinder motor is cooled is liquid cooling. In a liquid cooled motor, water or coolant is circulated through channels in the cylinder by a water pump that is usually driven by the motor. The water absorbs the heat from the cylinder and is pumped to the radiator, which has hundreds of tiny fins on the outside, and many grooves on the outside. The large surface area of these fins cools the water in the same way that the fins on a air cooled motor cool the cylinder. Liquid cooling is far more effective, because liquid transfers heat much better, than air, and the circulating liquid allows for faster cooling. Essentially all performance motors use liquid cooling because it allows the motor to run harder for longer. All new cars and trucks use liquid cooling, because the motor is inside an enclosed engine bay where fresh cold outside air can not circulate to cool the cylinders of an air cooled motor, also air cooling only works on motors with separated cylinders, while the cylinders in all new cars are in engine blocks.
The radiator in this picture is hard to see, its the large rectangle behind the shocks, and steering column.
Oil cooling is usually only found in performance motors. Unlike the first two cooling systems, oil cooling does not cool the cylinder. As a result oil cooling has to be paired with a cylinder cooling system, (pretty much always liquid cooling). Oil cooling cools the oil, using a device similar to a radiator, that the existing oil pump circulates the oil to. Cooled motor oil cools the bottom end of the motor, as well as all the parts it lubricates, There are two types of oil cooling, motor oil cooling, and transmission oil cooling. The motor oil mainly cools the bottom end of the motor, while the transmission fluid (oil) cools the gears in side a transmission. some industrial vehicles also have differential cooling, which is identical to transmission cooling.
And in case you didn't know, the differential splits power between the pairs of wheels while turning, taking power away from the inner wheel to allowing the outer wheel to turn at a faster rate than the inner wheel, resulting in easier turning, and no loss of traction. My quad has a solid rear axle and no differential. This means that in order to turn, the inside back wheel must break free and lose traction. Because of this the only way to effectively turn is to slide/drift which is awesome.
A transmission or gear box allows multiple graduated gears to be selected, this allows the vehicle to put as much power or tourque to the wheels at a given speed as possible. The gears are graduated, the gears start off low, allowing the motor to turn the wheels at a rate more closer to the motor rate, this allows for much faster acceleration, however, the motor will reach max RPM very quickly, and at a low speed, at this poin you simply shift into the next slightly higher gear and the process repeats itself. Gear boxes are very complicated and I won't explain them. Manual car transmissions are shifted by your hand on a stick, that must be placed in the correct shift spot or gate to select a gear. Motorcycle and quad transmissions are operated by a toe actuated shift lever on the left side of the bike. Unlike car transmissions, bike transmissions are sequential meaning you simply bump the shift lever up to shift up, and down to shift down.
A clutch is another incredibly important part of almost all motorized creations. The clutch transfers power form the motor to the gear box, and can be disengaged to allow for shifting. Clutches are found in many pieces of machinery. The most basic type of clutch would be the type of clutch a weed wacker or chainsaw has. These clutches are centrifugal clutches. The clutch uses springs to keep itself disengaged at low RPM allowing the motor to turn without engaging the implement. At higher RPM the centrifugal force on the clutch increases, overpowering the springs and allowing it to engage two friction plates, sending power to the implement (spinning the weed wacker, or turning the chainsaw chain). The clutches in manual cars are very different, and are manually operated. Naturally the clutch is engaged, and the clutch pedal must be depressed to disengage the clutch (separating the two friction plates). Without neutral, or a clutch, no vehicle, could really start, or be drive-able, because the wheels would always spin with the motor, meaning you could never stop without the motor dying, and starting would require enough force to move the car. The clutches found on motorcycles, dirt bikes and quads have multiple friction plates not just two. This is because the plates have to be much smaller, to fit in a small space on the side of the motor, a space where car sized friction plates could never fit. In order to make the clutch strong and prevent clutch slippage despite the small friction plates, multiple plates are used (my quad has 8 I think). the increased number of plates not only increases clutch friction, but makes the clutch significantly easier to disengage, which is very necessary consider you use a finger lever to disengage the clutch. To get a better understanding, heres a YouTube video of a clutch animation. https://www.youtube.com/watch?v=TcYsV063lk8
My Quad's Motor
My quad's motor is a 450cc single cylinder liquid cooled four stroke, with 4 valves, and two overhead cams. The 450cc, refers to the displacement, which is the volume of space in the cylinder when the piston is at the bottom of its stroke. 450cc is the same as 450 millilitres or 0.450 litres. To help show the different parts of my motor I have drawn right side and left side diagrams.
The Parts that are not side specific, such as the intake, system, exhaust system, and cooling system are not showed in the left side diagram because they are showed in the right side.
Tuesday 9 June 2015
Learning
This post will explain some of the things I have learned in this project.
the spark plug ignites the compressed air fuel mixture in a cylinder. It threads into the top of the cylinder, and uses a powerful electric spark, arking through the small gap at the tip of the plug to initiate combustion. Diesel motors do not have spark plugs,this is because the diesel air mixture in a diesel engine auto-combusts under the higher compression in the cylinders. Different spark plugs have different heat ratings that indicate how intense of a spark it can allow. The more intense the spark, the better the air fuel mixture will burn, resulting in a smoother more powerful motor. Running to hot of a spark can potentially damage the ignition system. the heat rating of my spark plug according to the owners manual is 9h.The carburetor, in the simplest of terms, provides the motor with the correct mixture of air and gas. I decided not to take it apart and clean it, because the carb is fairly complicated, especially with the electric throttle position sensor. Instead I poured a healthy amount of sea-foam engine cleaner into the gas. Sea Foam can help clean the carburetor and motor when burned in the gas. I also learned that it is important to run octane boosted premium gas in motocross engines, to keep the motor clean, and to get optimal performance.
My quads carburetor is a 38 millimeter (inner diameter) of . The carburetor is located in between the air box (right) and cylinder (left) as the motor draws in air from the air box during the intake stroke, the air is pulled through the carb where it is mixed with a small amount of fuel. The black hose connecting to the carb is the fuel line from the gas tank, it fills the float bowl (bottom of carburetor) with gas. The gas in the float bowl pushes a float, which allows gas up through several needles, there are several needles or jets, the 2 important ones are the idle jet, and the main (pilot)jet. The idle jet always allows squirts up a small amount of gas, regardless of throttle position allowing the motor to idle. the main jet allows more fuel into the air stream depending on the throttle valve position, ie you twist the throttle, and it allows more gas into the cylinder. The throttle also opens a large valve in the carburetor that controls air flow, the more throttle input, the wider the valve opens and the more fuel and air is drawn into the cylinder.
The top photo is a view of the throttle valve, the slight opening at the bottom is always open, it allows a small amount of air for the motor while its idling.
The air and fuel mixture does not need to be forced into the motor, the natural vacuum pressure caused by the piston going down draws the mixture through the intake valves with sufficient force. A A turbo charged or super charged motor forces more air into the cylinder than would naturally be drawn in under vacuum pressure. great deal of force in and into the air flowing through the carburetor. The orange hoses are overflow hoses, that allow excess gas to drain from the carburetor.
Goals
I have several different goals for this project. My primary goal is to restore the beat up sport quad I purchased back to a healthy operating condition. This will include fixing a mysterious, and debilitating, motor issue, repairing plastics, changing fluids, changing filters, and probably fixing new problems I discover while fixing the old ones. I hope that by the end of this project I will be able to rip on this quad with my friends, without having to worry about any problems.
My second goal is to learn as much as possible about the function and mechanics of the internal combustion motor, as well as maintenance, and servicing information. I believe that it is important to learn such things, because almost every adult uses at least 1 type of internal combustion motor on a near daily basis ( in the form of an automobile), and every motor requires semi frequent basis. By knowing how a motor workings and how to properly maintain and service it, you can not only save money by not having to take your motor to a shop for basic maintenance, you can prevent major problems by recognizing signs of a problem before it gets serious. I think that learning about motors will make my life easier in the future, and probably save me time and money.
My third goal is to learn because its fun. The interactions of moving parts of machines, motorized or not has always fascinated me, and I always want to know how they work. It never fails to amaze me how intelligently designed most mechanical devises, are I sometimes wish I could create such things. When I look at how a combustion engine works, I see a type of mechanical beauty. God has instilled upon man intelligence, and resources. He has given us both the mental, and physical resources necessary to create complex, and amazing things. I believe this project follows the religious through line of beauty creating, even though at fist glance, a greasy, smelly machine may seem anything but beautiful. I believe we can honor God in our work, using our christian values in the decisions we make, and the tasks we do.
My second goal is to learn as much as possible about the function and mechanics of the internal combustion motor, as well as maintenance, and servicing information. I believe that it is important to learn such things, because almost every adult uses at least 1 type of internal combustion motor on a near daily basis ( in the form of an automobile), and every motor requires semi frequent basis. By knowing how a motor workings and how to properly maintain and service it, you can not only save money by not having to take your motor to a shop for basic maintenance, you can prevent major problems by recognizing signs of a problem before it gets serious. I think that learning about motors will make my life easier in the future, and probably save me time and money.
My third goal is to learn because its fun. The interactions of moving parts of machines, motorized or not has always fascinated me, and I always want to know how they work. It never fails to amaze me how intelligently designed most mechanical devises, are I sometimes wish I could create such things. When I look at how a combustion engine works, I see a type of mechanical beauty. God has instilled upon man intelligence, and resources. He has given us both the mental, and physical resources necessary to create complex, and amazing things. I believe this project follows the religious through line of beauty creating, even though at fist glance, a greasy, smelly machine may seem anything but beautiful. I believe we can honor God in our work, using our christian values in the decisions we make, and the tasks we do.
The Ignition System.
The ignition system consists of a series of components that create, and time the electric spark used to ignite the gas and air mixture in the cylinder during combustion. I knew that the only ignition system was to blame, and not the bikes entire electrical system because all other electrical functions continued to work after the bike losses spark. Electrical problem can be notoriously hard to diagnose and fix, which concerns me. The ignition system on most dirt bikes and sport quads consists of a stator coil, ignition coil, cdi box, and voltage regulator and kill switch.
sometimes a faulty kill switch can cause such problems however, the rest of the electric components functioned flawlessly, when spark was lost. if the kill switch was the problem, the bike would essentially just turn off, and nothing would work.
My next suspicion was the stator coil, I had been talking with a Polaris mechanic and he said the problem might be the stator coil. the stator coil is a device mounted next to the flywheel, its turned by the motor, generating electricity for the spark, and charging the battery. On primitive motors the stator coil actually times the spark. Apparently the stator coil can crack over time, and still function properly when cold, however it will expand, and fail to generate electricity when hot. I was fairly confident that the stator coil was the problem, but then I learned something. Unlike kickstart quads and dirt bikes that don't have a battery, electric start machines use electricity from the battery, not the stator to generate spark. This means that even if the stator failed, the bike would run until the battery died. However on my Polaris the battery is still fully charged when the machine dies.
Another potential culprit could be the CDI (capacitive discharge ignition) box. The CDI box is essentially the brain of the machine. It times the spark, determining exatly when the spark is created, CDI boxes stores electrical charge, before discharging it to the ignition coil, this causes the spark to be much more powerful. Sometimes when a CDI box becomes old it malfunctions, resulting in spark not reaching the spark plug.
The ignition coil is another potential part at fault. the ignition coil converts the 12 volts charge from the CDI box to a short powerful spark, peaking at up to 10,000 volts. The spark has to be extremely powerful because its very difficult for an electrical charge to ark across the spark plug gap while under the extreme heat and pressure of the cylinder.
Another part that could be causing the problem would be the wiring harness. The wiring harness is a bundle of wires from, every electrical component. The wiring harness contains all the wires keeping them compact and organized. The wiring harness on the Polaris is in tough shape, and if the insulation on a wire from the ignition was worn out, the wire could short on the frame, preventing spark.
Trouble Shooting
As I mentioned in a previous post my polaris has an issue where the engine dies after about 10 minutes of run time. I learned that this can be caused by a lack of one or more of three main things. Any gasoline motor stops running if it fails to receive gas, air, or spark.
My first move was to see if it was getting gas, I theorized that perhaps the fuel tank wasn't venting properly, which would result in fuel being unable to reach the carburetor. However after a few minutes of running the motor with the gas cap open, it still died. This ruled out a gas tank venting problem, however it still could be caused by a partially clogged fuel filter restricting the flow of gas to the carburetor. Unfortunately after cleaning the fuel filter with compressed air, the motor would still die.
My next action was to check the air filter, (if not enough air gets though the filter the motor will run rich, and die) but it seemed ok, and the motor still died when it was removed. Both of these tests showed that the problem was either in the carburetor, or was an electrical ignition malfunction preventing spark.
Testing whether the motor is receiving spark is easy, you simply remove the spark plug and hold it against a metal part, while turning over the motor. If you see a strong blue ark come from the plug, all is usually good, if you don't, there's no spark. Obviously the motor receives spark initially, otherwise the motor would never start, I wanted to see if the the engine was dying once hot because of a lack of spark. I ran the motor until it died, pulled the plug, and sure enough it didn't spark. So the problem was electrical. The series of components that create and time the spark are called the ignition system, and one or more of these parts was failing after a few minutes of run time.
My first move was to see if it was getting gas, I theorized that perhaps the fuel tank wasn't venting properly, which would result in fuel being unable to reach the carburetor. However after a few minutes of running the motor with the gas cap open, it still died. This ruled out a gas tank venting problem, however it still could be caused by a partially clogged fuel filter restricting the flow of gas to the carburetor. Unfortunately after cleaning the fuel filter with compressed air, the motor would still die.
My next action was to check the air filter, (if not enough air gets though the filter the motor will run rich, and die) but it seemed ok, and the motor still died when it was removed. Both of these tests showed that the problem was either in the carburetor, or was an electrical ignition malfunction preventing spark.
Testing whether the motor is receiving spark is easy, you simply remove the spark plug and hold it against a metal part, while turning over the motor. If you see a strong blue ark come from the plug, all is usually good, if you don't, there's no spark. Obviously the motor receives spark initially, otherwise the motor would never start, I wanted to see if the the engine was dying once hot because of a lack of spark. I ran the motor until it died, pulled the plug, and sure enough it didn't spark. So the problem was electrical. The series of components that create and time the spark are called the ignition system, and one or more of these parts was failing after a few minutes of run time.
If the spark is weak when outside the cylinder, it may actually be unable to spark at all, under the extreme pressure of a cylinder.
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