Motorcycle school Ⅱ- What you need to know about motorcycles

Everything you want to know about motorcycle is here.
Motorcycles have evolved over the years and are now being made with more and more sophisticated technology, and there are more and more types and models of motorcycles. Do you get confused when choosing a motorcycle and can't decide because there are so many models? This article will take you through the various knowledge of motorcycles in detail.
Basic knowledge
Working principle
Common faults and troubleshooting
Parts Maintenance

  1. Origin
In 1885, the world's first motorcycle was born when a German, Gottlieb Daimler, installed an engine into a framed machine. Motorcycle-related motorcycling, on the other hand, is a military sport, a competitive sport with motorcycles as the apparatus. There are two types of motorcycles, two-wheeled and three-wheeled, and each type is divided into several classes according to the working volume of the engine cylinder. It can be divided into cross-country, multi-day, road, track and touring races. Driving speed or driving skills to assess the ranking.
  1. Development
  • Originated from Motor (internal combustion engine) and Cycle engine
In 1884, the Englishman Edward Butler added a power unit to a bicycle to make a three-wheeled vehicle powered by kerosene, and in 1885, the German "father of the automobile" Trieb Daimler made a three-wheeled motorcycle powered by a single-cylinder wind-powered gasoline engine. He received the patent for this invention on August 29th of the same year. Daimler is therefore recognized worldwide as the inventor of the motorcycle. Daimler's first motorcycle was powered by a four-stroke internal combustion engine with a cylinder working cellar of 264 cubic centimeters and a power of up to 0.5 horsepower at 700 revolutions per minute and a speed of up to 12 kilometers per hour. The car is a wooden structure with a belt-driven rear wheel and auxiliary support wheels on both sides. In view of this irreplaceable historical position of Daimler, the Eudenberg branch of the German Engineers' Association erected a monument to him after his death at the Hewettplatz in Kam, where he drove his first motorcycle.
  • Brief history of motorcycle development

Since 1885, when Daimler invented and manufactured the world's first gasoline-powered motorcycle, the motorcycle has undergone more than 100 years of dramatic changes.
The original motorcycle, now in its true form at the Museum of Science and Technology in Munich, Germany, was the world's first motorcycle invented by German Daimler, who received a patent on August 29, 1885.
The original motorcycle differed greatly from the modern motorcycle in appearance, structure and performance, as the gasoline engine was still in its infantile state and vehicle manufacturing was still at the stage of horse-drawn carriage technology more than 100 years ago. The frame of the primitive motorcycle is wooden. The wheels were also made of wood, and the outer layer of the wheels was covered with a layer of iron. At the bottom of the frame were several square wooden frames on which the engine was placed, and there was a small support wheel on each side of the frame to prevent it from tipping over when it was stationary. Therefore, the car is actually four wheels on the ground. Single-cylinder fan-cooled engine, the output power through the belt and gear two-stage reduction transmission, drive the rear wheels forward. The seat is saddle-shaped and covered with a layer of leather. The working volume of the engine cylinder was 264mL and the maximum power was 0.37kW (700r/min), which was only 1/5 of a modern simple motorcycle. 12km/h, which was not much faster than walking. Since there was no spring and other cushioning devices, the car was called a "bone shaking car". As you can imagine, driving on the stone-striped streets of the 19th century was even more unbearable than execution. Although the original motorcycle was so rudimentary, motorcycles have continued to change and improve since then, resulting in more than 100 years of hundreds of millions of modern motorcycle descendants.
The American motorcycle, known for the Harry Davidson Company, was the first to be marketed in 1903 (the earliest commercial motorcycle in the United States), with a 409mL engine cylinder and 2.94kW power, and a bicycle frame. Motorcycles are a product of their time and an example of the level of science and technology at the time, i.e., the brand of technological development of different times is gathered on motorcycles at different stages. The original motorcycle was not usable because the science and technology of the time could not meet the most basic components needed to run properly, and thus could only be placed in the laboratory. Motorcycles began to have practical value and were mass-produced in factories to become commodities, which is the second generation of motorcycles, known as the commodity generation. This was the second generation of motorcycles, known as the commercial generation. In 1912, the American Harley Company produced the X-8A single-cylinder motorcycle. At that time, the transmission and drive system had not been solved, but the large pulley attached to the rear wheel was driven by a belt, and the brake was applied by pulling the rear brake by the handle. There was no solution to the rear shock problem, and the front shock absorber was a simple shock device attached to the front fork.
After the 1930s, as science and technology continued to advance, motorcycle production adopted rear suspension shock systems, mechanical ignition systems, drum mechanical brakes, chain drives, etc., bringing motorcycles to a new level of maturity, and they were widely used in transportation, competition and military applications. This was the third stage of motorcycles - the mature stage. by 1936, the American Harry Company was able to produce a high level of motorcycles. It was powered by a 1000mL, OHV, 27.93kW V-twin engine with a top speed of 150km/h.
Motorcycles developed like a tier of steps, getting more advanced the higher up they went. the original motorcycle from 1885 was laid out on the ground in the first tier, the second tier was the first motorcycle produced in the world, a German motorcycle bike with a two-cylinder, four-stroke engine from 1894, of which 1,000 were produced. The third tier is the popular race motorcycles of the 1930s, when motorcycles already had practical functions. The fourth tier is the modern luxury motorcycles after the 1970s. The figure not only shows the four stages of motorcycle development, but also configures the different attire of the drivers of the vehicles in the four stages.
After the 1970s, motorcycle production also adopted electronic ignition technology, electric start, disc brakes, streamlined body guards, etc., as well as exhaust gas purification technology and ABS anti-lock braking devices in the 1990s, making motorcycles advanced motor vehicles with beautiful shapes, superior performance, ease of use, flexibility and speed, and becoming one of the important symbols of contemporary earth civilization. In particular, large-displacement luxury motorcycles have transplanted the advanced technology of today's automobiles to motorcycles, making motorcycles reach the realm of perfection. The development of motorcycles has entered the fourth stage - the heyday stage.

1. America
The United States was one of the first countries to manufacture motorcycles, with famous companies such as Harley-Davidson and Indian.
Harley motorcycles have become a symbol of a nostalgic era. 1907, Harley-Davidson manufactured the first V-twin engine, which could provide twice the power of a motorcycle compared to a traditional single-cylinder engine. This style of engine has dominated the history of motorcycle manufacturing in the United States for more than 80 years. In the 1930s, Harleys topped sales on American soil; by the 1940s, Harleys were challenged by British motorcycles, which were lighter and faster; in the early 1960s, small-displacement Japanese motorcycles flooded the U.S. market; in 1969, Harley and American Machine & Foundry merged, strengthening the capital and resource market; and in the late 1980s, Harley motorcycles was fully revitalized, and every motorcycle it produced was a guarantee of quality. The Indian Company is a distant star that once shone brightly, starting in 1899 when engineer Oscar Hyde built a motorized two-wheeler. For a while, Indian conquered buyers with its bright colors and excellent performance, then was thwarted by several changes of ownership and some short-sighted investments, ending its historic mission in the 1950s.
The characteristic that distinguishes Harley from BMW is that Harley is almost all metal and has a timeless look and feel. Whereas BMWs are mostly plastic shells similar to the same as Japan. So you can see many Americans driving a Harley motorcycle from their youth until old age.
2. Japan
Japan is undoubtedly the representative of modern Asian industry, and this is also true in the motorcycle manufacturing industry. Honda, Suzuki, Yamaha and Kawasaki are four of the most famous Japanese motorcycle companies. Among them, Honda and Yamaha started out in the last century by imitating Italian Piaggio, German BMW and American Harley. To this day we can still see many Honda models and the size and even the details of these cars are identical enough to pass off as real. The only difference is that now Yamaha has started to create its own or change a bit on others' creations, while Honda has been still dedicated to imitating others' shells.
The beginnings of Japanese motorcycle manufacturing can be traced back to the early nineteenth century, but it really took shape after World War II. Due to the disaster of the war, Japan was in financial chaos, public transportation was out of order, and the market was in desperate need of cheap, convenient personal transportation. Against this background, a number of companies emerged, such as Honda. Honda began exporting motorcycles overseas in 1959, followed by Suzuki, Yamaha and Kawasaki. At that time, the competition among the four major companies in the Japanese domestic market was fierce, which in turn prompted each company to work hard on the design and manufacture of new models and marketing, and to quickly capture the world market. The world's most successful British manufacturer was standing still. By 1961, Honda had become the world's largest motorcycle manufacturer.
Japanese motorcycles were characterized by beautiful appearance, comfortable driving, and very careful and thoughtful attention to some details, all of which were standard equipment in Japanese motorcycles, even on 125ml displacement cars, which surprised buyers.
By 1969, Honda, with a CB750, had broken through the large motorcycle market that British manufacturers had been holding onto, marking the dawn of the Japanese motorcycle era, while providing a properly equipped motorcycle for the first-rate market.
Japan also put a lot of effort into its marketing strategy on motorcycles, and from time to time would produce motorcycles according to the policies of certain countries. For example, at that time, the standard in China was that no license would be granted for 125cc or more, and Yamaha, Honda and Suzuki actively cooperated.

3. Germany
Germany is the birthplace of motorcycles, and the company we know best is BMW.
In 1921, BMW began producing twin-cylinder engines for motorcycles, and in 1923, BMW's aircraft designer, Max Fritz, unveiled the first motorcycle engine. The 500ml engine was mounted in the frame with the cylinders sticking out to the sides, a simple but efficient design still in use today. bmw motorcycles are known for their fine manufacturing process and high prices. In the field of car sales there is a market rule that whether a car sells well or not is known by how Germans react to it, and this rule also applies in the motorcycle market. BMW is world-renowned for its exceptional quality, and its motorcycles are the choice of many countries for their ceremonial motorcades.
BMW is characterized by a superb array of high-tech electronics, and it is no wonder that the Honda Gold Wing is copying it.


4. China

In August 1951, China officially started its own trial production of motorcycles, and the six plants of the then Beijing Automobile Production and Assembly Factory of the Chinese People's Liberation Army completed the trial production of five heavy-duty military motorcycles, which were named Jinggangshan by the Central Military Commission. The vehicle's speed could reach up to 110 kilometers per hour. By 1953, the annual output of Jinggangshan two-wheeled motorcycles exceeded 1,000 units. The introduction of Jinggangshan motorcycle marked the beginning of a new era in China's motorcycle industry.
In the past decade, China's motorcycle industry has developed at a much faster pace. In terms of product output, annual production has grown from 49,000 units in 1980 to 970,000 units in 1990 to more than 10 million units today. China has leapt to become the world's largest producer of motorcycles, and motorcycles have become an important part of the automobile industry, the pillar industry of China's national economy.
China's motorcycle industry saw a significant increase in production and sales in 2006, reaching a new record high. The total annual production of motorcycles was 21,443,500 units, an increase of 3,676,300 units over the previous year's 17,767,200 units, an increase of 20.69%; the total sales of motorcycles was 21,266,700 units, an increase of 3,251,700 units over the previous year's 17,745,100 units, an increase of 19.85%. In 2006, 105 motorcycle manufacturers in China achieved a total business income of 81.629 billion yuan, an increase of 15.59% over the previous year, an increase of 11.008 billion yuan; total profit of 2.475 billion yuan, an increase of 49.81% over the previous year, an increase of 823 million yuan.
China's motorcycle industry after half a century of trials and tribulations, the formation of a relatively complete production, development, marketing system, a considerable part of independent and independent intellectual property rights, a number of brand-name products covering the market. Especially since the reform and opening up, the motorcycle industry has been rising rapidly. After a difficult journey of start-up, development, integration and reorganization, ups and downs, and through the efforts of the motorcycle industry, China has now become one of the world's leading motorcycle producers.


5. Italy
Italy's heavy industry, light industry, and tourism are all very well developed, and of course, motorcycles are also very well developed. However, because the culture and taste of our people have been very low, many European and American brands are not known by the people. In addition, Italy is dominated by small and medium-sized enterprises, so for the Chinese people who judge brands by their large factories, they certainly have little knowledge of them.
In 1946, the movie "Roman Holiday" was popular all over the world, in which the romantic love story infected everyone and has been passed down to this day. The scooter driven by Hepburn is VESPA from Italy Piaggio, also known as Vespa or Wasp, the car is not like the Japanese motorcycle scooter using plastic shell, but the full steel pressed frame, so the durability is very high. 40s, 50s VESPA can be seen. There are already 50 million units sold worldwide. India 3 million units, Vietnam 1 million units, and China less than 10 units. Currently Piaggio is partnered with Zongshen in China.
Now Piaggio has acquired most of the motorcycle manufacturers in Europe, namely Apulia, Spanish Derby, Girella, Guzi and many other brands. Most of the parts of France's iconic motorcycles are almost all from Piaggio.
Ducati, the luxury of motorcycles, but has the name of the Ducati that can't be driven badly.
Malaguti, heavy-duty locomotive, quality and quality, can be on par with the following Agusta.
MV Agusta, nicknamed the Lamborghini of motorcycles, the Ferrari of two wheels, currently in cooperation with Lifan.
Bombardier, see Spider-Man's ride, that is Bombardier.
Italo Czech, which like Piaggio has produced full steel scooters.
Also Agusta makes helicopters, and Piaggio and Bombardier make private jets.
There are still many Italian motorcycle brands, and Japanese motorcycles are different, Italian motorcycles are excellence, durability, not easy to break, perfect design, as opposed to only imitate, put together (Japanese motorcycle design is very little, put together a lot of) marketing of Japanese motorcycles, Italian motorcycles if you want to be known by the country, the only way to stand firm is to increase publicity.
Of course, Italian motorcycles are the most threatening to Japanese motorcycle dealers.

  1. Classification
  1. Basic Knowledge
Knowledge of Power
Horsepower was originally developed by the French and Germans, but since the horse they measured horsepower on was a small horse of smaller size than the average horse, an engine with 50 horsepower could not be imagined to have 50 horsepower to pull a motorcycle around, but should be imagined to have 35 horses. The unit of horsepower (ps) was the first symbol used by the Germans, and is still used today.
What is 1 horsepower? 1 horsepower is the force of pulling an object weighing 75 kilograms (kg) up 1 meter (m) in 1 second, which is called 1 horsepower.
rpm is the abbreviation for engine revolutions per minute.
What is torque? Torque, also called torque, is the torque that makes the shaft rotate. The common unit of torque in XXX is kg-m (international unit is Nm).
To better understand the concept of torque, here are a few examples. For example, if a screw is tightened with a driver or a wrench, and the length of the driver or wrench is 1 m, a force of 1 kg is applied to one end of the driver or wrench, the tightening torque of the screw is 1 kg-m. If the length of the driver or wrench is 0.5 m, a force of 2 kg must be applied in order to obtain a torque of 1 kg-m. The reverse is also true. If the driving torque is the same, the further away from the center of rotation, the less force is generated.
Exhaust volume
How is the exhaust volume calculated?
Bore - the diameter of the cylinder.
Stroke - The distance traveled by the piston as it makes a reciprocating motion in the cylinder, when the piston runs from the upper stop (TDC), to the lower stop (BDC), is called the piston stroke, abbreviated as stroke or stroke.
Now take '03 Honda CBR600RR as an example, engine form: water-cooled four-stroke parallel four-cylinder 16-valve DOHC engine as an example.
Bore (67.0mm) and stroke (42.5mm)
Displacement calculation method.
Cylinder cross-sectional area X stroke X number of cylinders = total exhaust cc
Stroke - 42.5mm = 4.25cm
Bore - 67.0mm = 6.7cm
Discontinuous area - 3.35 X 3.35 X 3.1416 = 35.25
Break area 35.25 X stroke 4.25 X number of cylinders 4 = total exhaust volume 599cc
  1. Working Principle
The working principle of four-stroke engine and two-stroke engine as an example.
Four-stroke engines are widely used, four-stroke engines, which means that the piston does four reciprocating motion cylinder ignition once every four times. Specific working principles are as follows.
  1. intake: at this time the intake valve is open, the piston goes down, the gasoline and air mixture is sucked into the cylinder.
  2. Compression: At this time, the intake and exhaust valves are closed at the same time, the piston goes up, and the mixture is compressed.
  3. Combustion: When the mixture is compressed to the minimum, the spark plug ignites the mixture, and the pressure generated by combustion pushes the piston down and drives the crankshaft to rotate.
  4. Exhaust: When the piston goes down to the lowest point when the exhaust valve opens, the exhaust gas is discharged, and the piston continues to go up to discharge the excess exhaust gas.
Two-stroke engine principle of operation as the name implies two-stroke engine is the piston up and down two strokes, the spark plug ignition once. Two-stroke engine intake process is completely different from the four-stroke engine, two-stroke engine to go through two compression, in the two-stroke engine, the mixture first flow into the crankcase before flowing into the cylinder, to be exact, should flow into the combustion chamber, while the four-stroke engine mixture is directly into the cylinder, four-stroke engine crankcase is used to store oil, two-stroke engine because the crankcase used to store the mixture can not store Oil so two-stroke engines with oil is not recyclable combustion oil.
Two-stroke engine work process is as follows.
  1. Piston upward movement of the mixture flow into the crankcase.
  2. Piston down to the mixture of air pressure to the combustion chamber, complete the first compression.
  3. mixture to the cylinder after the piston up the intake and exhaust ports are closed, when the piston compresses the gas to the minimum volume (this is the second compression) spark plug ignition.
  4. The pressure of combustion pushes the piston down, when the piston goes down to a certain position the exhaust port opens first, the exhaust gas is discharged and then the intake port opens, the new mixture enters the cylinder to squeeze out the remaining exhaust gas.
In the same speed because of two-stroke engine than four-stroke engine combustion times more than once, so the power, and two-stroke engine than the same displacement of four-stroke engine lighter, so in the racing two-stroke car overwhelming advantage, but because the two-stroke engine intake and exhaust at the same time, when the engine speed is low due to the exhaust port open too long, there will be part of the fresh mixture along with The new two-stroke engine has added some parts to improve the problem such as YAMAHA YPVS, HONDA ATAC SUZUKID's SAEC. due to the carbon generated by burning oil and open inlet and exhaust holes in the cylinder wall, the two-stroke engine wears much faster than the four-stroke engine.
  1. Composition
The motorcycle consists of five parts: engine, transmission system, running system, steering, braking system and electrical instrumentation equipment. The general structure of a motorcycle and the names of each part.
1、Characteristics of motorcycle engines
(1) The engine is a two-stroke or four-stroke gasoline engine.
(2) Air-cooled cooling is used, with natural air-cooling and forced air-cooling. General models rely on the air blowing through the cylinder head, cylinder liner heat sink to take away the heat of the natural air-cooled cooling method. High-powered motorcycle engine in order to ensure that the speed is low and not start driving before the engine cooling, the use of fans and wind shields, the use of forced into the air blowing cold heat sink forced air-cooled cooling method.
(3) The engine speed is high, generally above 5000 rpm. Liter power (effective power issued per liter of engine displacement) is large, generally in the 60 kW / liter or so. This indicates a high degree of strengthening of the motorcycle engine and a small engine form factor.
(4) Engine crankcase and clutch, gearbox design as one, compact structure.
2、Engine body
The body consists of cylinder head, cylinder block and crankcase three parts, cylinder head by aluminum alloy casting with heat sink, the new four-stroke motorcycle engine are overhead valve, chain drive, overhead camshaft structure way. Cylinder block material to bimetal (wear-resistant cast iron cylinder liner outside cast aluminum heat sink) for more, in order to get better heat dissipation effect. Some motorcycles use wear-resistant cast iron cylinder, such as Yangtze 750, Jialing JH70 type, in some small mopeds, such as Yuhe brand YH50Q small displacement (50 cm3) engine using aluminum alloy cylinder wall plating 0.15 mm hard chrome layer structure. The crankcase is made of aluminum alloy die-casting by the combination of the left and right two boxes. Some motorcycles have a buffer block between the heat sink signs to suppress the noise from the vibration of the heat sink.
  1. Crank connecting rod
The crankshaft of a motorcycle engine is a combination of a left half crankshaft, a right half crankshaft and a crank pin. The main journals of the left and right half shafts are equipped with ball bearings to support the crankshaft on the crankcase. The two ends of the crankshaft are equipped with flywheel, magneto and clutch active gear respectively. The connecting rod is a monolithic structure, the big head is circular, equipped with needle bearings and crank pin combination into a crank connecting rod group. In the two-stroke engine piston ring in the installation should pay attention to the opening of the piston ring aligned with the positioning pin in the piston ring groove to prevent the piston ring in the ring groove rotation, resulting in air leakage, scratching the cylinder liner on the intake and exhaust port.
  1. Carburetor
The carburetor is an important part of the motorcycle fuel supply system, located between the air filter and the engine intake. The general motorcycle engine uses a flat suction type intake airflow direction, a plunger type throttle valve, and a float chamber type carburetor. The carburetor structure is composed of two main parts: the float chamber and the mixing chamber. The float chamber is located underneath the carburetor, there is a fuel pipe through the fuel tank by the throttle switch, through the needle valve on the float, to maintain a certain height of the oil surface inside the float chamber, so that the fuel supply pressure is stable. The role of the mixing chamber is to evaporate the gasoline atomization and air mixing, so that the engine can get the required mixture under various loads and speeds. It is composed of throttle valve, injection needle, injection pipe and gas and oil channel.
Through the rotation of the motorcycle throttle handle to drive the throttle wire tether to manipulate the throttle valve and the up and down movement of the injection needle, changing the intake pipe section and the amount of fuel supply to adapt to the needs of the mixture at different speeds and loads. On one side of the carburetor, there is an idle speed adjusting screw to adjust the idle speed. The idle speed stop screw is used to prevent the throttle valve from turning and to adjust the minimum opening of the throttle valve. There is a return spring above the throttle valve to keep the throttle valve closed when the throttle handle is not turned.
In some two-stroke motorcycle engines, in order to avoid low-speed carburetor back spray phenomenon, between the carburetor and the cylinder block is equipped with a one-way reed valve to control air intake. The reed is made of thin spring steel, the valve seat is made of aluminum alloy, on the opening of the air inlet, the inlet plane and reed contact parts are pasted with a layer of oil rubber to reduce the impact of the reed and valve seat and vibration. In the suction, the crankcase to form a certain degree of vacuum, the role of differential pressure reed valve open mixture into the crankcase, when the piston down, the gas exchange port has not been opened instantly, the crankcase pressure rises, the reed valve closed to prevent the mixture backflow, improve the power and economy of the dynamic engine at low speeds.
5、Lubrication system
Four-stroke engines use splash lubrication and pressure lubrication combined with the lubrication method. Two-stroke engines are generally used in the gasoline mixed with a certain percentage of the QB grade gasoline engine oil lubrication mixture. But this lubrication way of mixed oil regardless of engine conditions, have been set according to the proportion of the supply of lubricating oil, increasing the consumption of lubricating oil, incomplete combustion, more carbon, there is exhaust pollution. The new generation of two-stroke engines are using separate lubrication method, the device has a separate lubrication oil tank and oil pump. The oil pump generally uses reciprocating plunger type variable oil supply oil pump, driven by the crankshaft gear through the worm wheel, worm gear. The oil supply is linked to the carburetor throttle valve through the throttle handle and the steering cable, so that the oil supply changes with the change of engine speed, supplying more oil at high speed and less oil at low speed, which is reasonable and can save more oil compared with the mixed lubrication method. The oil is blown into a tiny oil mist by the high-speed mixture, which is supplied to the part that needs to be lubricated, reducing the oil entering the combustion chamber, and the mixture burns completely, reducing carbon and exhaust pollution.
The starting method of motorcycle is mainly by foot pedal. The starting mechanism is the fan gear starting mechanism represented by the XF250 motorcycle. The foot pedal starting gearshift drives the fan gear, starting ratchet, clutch assembly sprocket, front chain and crankshaft sprocket to rotate the crankshaft and start the engine. When the engine is started, the starting mechanism is restored to its original position by the one-way action of the starting ratchet and the action of the return spring. This kind of starting mechanism, when starting the starting gearshift to the neutral position, step on the foot pedal can start.
Another kind of starting mechanism is the starting stirrup type used by some imported models. Different from the former one, when starting, the clutch handle should be squeezed firstly to make the clutch disengage, and the gear lever can be put in any gear position, not necessarily in neutral, after starting, release the clutch and increase the throttle to start. When the starting stirrup is depressed, the pawl on the starting stirrup shaft engages with the inner pawl of the starting stirrup transmission gear, which makes the transmission gear rotate and drives the crankshaft to start the engine by idling gear, driven gear, clutch gear and starting pinion gear. After starting, the foot leaves the starter stirrup and the reset spring causes the stirrup to reverse and the pawl to disengage with the inner ratchet, restoring the original position.
Transmission System
The transmission system of a motorcycle consists of primary reduction, clutch, gearbox, secondary reduction and other components.
  1. Primary reduction
The primary reduction mainly consists of the active sprocket (active gear) mounted on the crankshaft end, the sleeve roller chain and the driven sprocket (driven gear) on the clutch, which acts as a primary reduction and transmits the engine power to the clutch.
Motorcycle clutch has the following types of structure.
(1) Wet multi-plate friction clutch assembly is immersed in engine oil and works in three parts: active, driven and disengaged. Engine power through the sprocket gear drive active cover, cover the periphery of the groove, five signs embedded with rubber cork friction material friction plate (active plate), the outer edge of the bump placed in the groove of the active cover with the rotation of the active part of the clutch. The four steel driven plates are connected to the driven plate fixing basin through the inner teeth to form the driven part. The main and driven plates are staggered and the fixed basin is connected to the gearbox main shaft with internal splines. The four clutch springs on the gland press against the friction and driven plates and transmit the power to the gearbox. The clutch is a constant engagement type. When the clutch handle is tightly squeezed to make the screw sleeve rotate in the left cover through the steel cable, the adjusting screw in the screw sleeve moves right to push the separation push rod and the gland, the spring pressure disappears, and the friction sign is separated from the driven plate.
(2) Automatic centrifugal clutch This structure is used in Yamaha CY80, Suzuki FR50 and other mopeds to automatically control the separation and engagement of the clutch according to the high and low engine speed. The clutch consists of active, driven and disengaging mechanism. The active part consists of clutch cover, thrust plate, clutch plate, etc. The driven part is composed of friction plate, center sleeve, etc. When the engine is running, as the speed increases, the centrifugal force generated by the steel ball increases, and its axial force overcomes the tension of the separation spring and moves outward along the groove in the clutch housing, pressing the thrust plate against the clutch plate and the friction sign to keep the clutch in the engaged state and output the power. When the engine speed decreases to idle or stalled, the centrifugal force of the steel ball decreases or is absent, and the tension of the release spring overcomes the centrifugal force of the steel ball to return to the original position along the groove, and the clutch is separated.
(3) Shoe automatic clutch This structure is used in some micro motorcycles, the active part is a fixed seat driven by the crankshaft, and there are three shoe assemblies on the seat, and they are connected to the fixed seat with a pin, and the spring pulls the shoe toward the center of the crankshaft to keep a certain gap between the shoe of the shoe assembly and the clutch disc of the driven part. When the rotational speed increases, the centrifugal force generated by the shoes is greater than the pulling force of the spring, it is thrown outward, and when the centrifugal force reaches a certain value, it engages with the clutch disc, generating friction to drive the driven part to rotate and transmit power.
  1. Secondary reduction and transmission
Depending on the type of motorcycle, there are three types of transmission: belt drive, chain drive and universal joint shaft drive. In micro motorcycles, belt drive is mostly used as the rear drive, and the size of the main and driven pulleys determines the secondary reduction ratio. General motorcycles use chain drive as the rear drive. The chain transmission is simple in structure, with few parts, and easy to manufacture and repair. There is a rear drive active sprocket on the output shaft of the gearbox and a driven sprocket on the rear wheel, and the power is transmitted by the corresponding sleeve roller chain. In motorcycles with larger engines (such as the Yangtze 750 motorcycle), the rear drive adopts universal joint shaft drive, and is equipped with a spiral bevel gear in the rear wheel to finance the stage reduction.
Travel system
The role of the travel system is to support the weight of the whole car and the load, to ensure the stability of the maneuvering and the comfort of the ride. The travel system mainly includes the frame, forks, front shock absorber, rear shock absorber, wheels, etc.
  • Frame:It is the skeleton of the entire motorcycle, made of welded steel tubes and plates. It connects the engine, transmission, front fork and rear suspension to each other and has high strength and rigidity. Small motorcycles mostly use steel plates stamped and welded into a spine type frame. General motorcycles use a steel tube welded frame, cradle type frame or a combination of steel plate and steel tube frame. Some high-powered motorcycles use a double-bracket cradle frame with welded steel tubes.
(2) Front fork: The front fork is the guiding mechanism of the motorcycle, which organically connects the frame to the front wheel. In order to make the steering column flexible, axial thrust ball bearings are installed in the upper and lower journals.
(3) Front and rear shock absorbers: The front shock absorber is used to attenuate the vibration caused by the impact load of the front wheel and keep the motorcycle running smoothly.
The rear shock absorber and the rear swing arm of the frame form the rear suspension of the motorcycle. The rear suspension is the elastic connection between the frame and the rear wheel, which bears the motorcycle's load, mitigates and absorbs the shock and vibration transmitted to the rear rotation due to uneven road surface.
  • Wheels:The front wheels of a motorcycle are the guide wheels and the rear wheels are the driving wheels. The wheel consists of tires (inner and outer tires), rims, spokes, hubs, brake rims, bearings, and front and rear axles. The rim (steel ring) is rolled and welded by steel plate, the hub is die-cast by aluminum alloy, and the brake rim is inlaid and die-cast into one, and there are flanges at both ends to install the spokes. The spokes are similar in appearance to the bicycle bars and are used to connect the rim and the hub. The hub is equipped with a brake, the front wheel is also equipped with a speedometer worm wheel, worm gear, and the rear wheel is equipped with a drive mechanism.
Steering and Braking System
(1) Steering: The front wheel and the handlebar control the direction of the motorcycle. The handlebar is mounted on the upper linkage plate. When the handlebar rotates around the steering column, the upper and lower linkage plates rotate and drive the front wheel to turn left and right through the front shock absorber. The right end of the handlebar is equipped with a throttle handle to control the size of the carburetor throttle valve and a gate to control the front wheel brake; the left end is equipped with a grip and handle to control the clutch. At the left and right ends of the handlebars are also equipped with rearview mirrors and various electrical switches. The handlebar and brake handle control the front wheel brake, clutch and carburetor through the steel cable. Steel cable has different specifications, brake and clutch with 1 × 19 outside diameter ∮2 ~ ∮2.5 mm single-stranded steel wire rope, carburetor with 1 × 7 outside diameter ∮1.2 ~ ∮1.5 mm single-stranded steel wire rope.
(2) Braking: Generally, the front wheel brake is controlled by hand squeezing the brake handle, and the rear wheel brake is done by foot pressing the brake pedal. Motorcycle braking devices are mechanical drum brakes and hydraulic disc brakes. Drum brakes are similar in structure to automobiles and tractors. The brake shoes are made of die-cast aluminum alloy with friction pads glued on top, and the brake cam is rotated by the brake arm and pushed away from the brake shoes for the purpose of braking.
The brake is composed of oil tank, plunger valve oil pump (all on the handlebars), hydraulic oil pipe, brake caliper, brake disc, etc. The brake stagger is fixed together with the fork guide, which is the fixed part of the braking device. The brake disc is fixed with the wheel and rotates with the wheel. When braking, hold the gate handle, the plunger valve moves, pushing the hydraulic oil along the hydraulic oil pipe into the two cylinders of the brake caliper. Under the action of pressure oil, the cylinder pushes the friction pad to clamp the brake disc from both sides, generating a large friction resistance and forcing the wheel to stop rotating. When the gate is relaxed, the pressure in the hydraulic oil circuit quickly back down, the cylinder drives the friction pads to restore the original position, lifting the brake.
  1. Common Failures
Failure Analysis
1、Blue smoke from the exhaust pipe
The fault phenomenon of blue smoke is: during the engine working process, light blue smoke is often seen at the end of the exhaust muffler, and there is the phenomenon of excessive oil consumption. The reasons for the failure may be: the oil level is too high; the cylinder compression pressure is lower than the specified value; the clearance between the piston, piston and cylinder barrel increases.
2 black smoke from the exhaust pipe
The black smoke fault phenomenon is: the engine work, the exhaust pipe black smoke, and can smell the pungent gasoline smell, acceleration is more obvious. The cause of the failure may be: the mixture is too rich; spark plug is not working well; ignition is too late.
3 white smoke from the exhaust pipe
White smoke original fault phenomenon is: the engine work, white smoke from the exhaust pipe. The cause of the fault may be: fuel containing water; cylinder or muffler with water.
1, blue smoke from the exhaust pipe
First of all, check whether the oil level is too high, because the oil level is too high to cause the oil to run up. When checking the oil level, do not check just after the engine has stopped, but 10 minutes after it has stopped. If the oil level is too high, the excess oil should be drained in time. If the oil level is normal, for longer engines, check the cylinder compression pressure and piston, piston ring and cylinder wear and tear and the possibility of increased clearance, increased clearance so that the oil up. After inspection, the cylinder pressure is lower than the specified value, should further check whether the piston has carbon seized, wear too much or elasticity disappeared. If the above situation, the piston ring should be cleaned or replaced. For the cylinder barrel wear serious, piston and barrel clearance exceed the specified value, do boring, replace the piston and other disposal.
For just after the overhaul or change the piston ring engine, often due to the piston ring inside and outside the cut (or cut angle) installed on the wrong oil. If the above situation, the piston ring should be reinstalled.
2, black smoke from the exhaust pipe
Check the concentration of gas mixture. After the symptoms of failure, first check the carburetor damper. In the normal operation of the engine, whether there is X longitudinal mechanism stuck, failure and can not close, open the phenomenon, if there should be repaired or replaced. Next, you should also check: whether the float chamber oil level is too high; whether the float is broken and cannot float; whether the main volume hole needle valve is too open; whether the air filter is blocked, etc. After the engine is turned off, look at the main jet from the carburetor, if there is oil flowing out or dripping, it means that the float chamber oil level is too high, the float should be adjusted by bending the tongue piece upwards appropriately or adding appropriate shims under the needle valve acne. Check the float, if there is rupture and oil leakage, it should be welded and repaired or replaced. Note that the weight of the welded float will be increased and must be re-adjusted when installed to ensure the normal liquid level. Check whether the triangle needle valve is not sealed tightly, if so, it should be replaced. Check the oil filter, if there is a blockage phenomenon, should be cleaned or replaced.
Check the spark plug jump fire situation. If the spark plug jump fire weak or jump fire is not normal, mixed full gas will not be able to burn, there will be black smoke conditions. If the spark plug is not jumping along the electrode, but jumping around the spark plug, it means that the spark plug is not normal and should be replaced with a new spark plug; if the spark plug has
The engine exhaust line in the process of black smoke can be, if the pieces have "burst" sound and "release" sound, it means that the ignition is too late. If the above-mentioned situation, correct in time.
3 white smoke from the exhaust pipe
White smoke from the engine exhaust pipe is mostly caused by the fuel containing water in the cylinder and water in the muffler. If there has been white smoke phenomenon, indicating that the fuel is not qualified, should be replaced with good quality fuel. If only white smoke when starting, disappear after normal operation, this problem is not a concern.
4、Lack of power
Such cases are mostly piston ring aging seal is not good, the valve is not closed or carburetor blockage! Should replace the piston ring. Valve and cleaning carburetor.

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