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75-440: KF1 was the top level of karting . It is open to drivers aged 15 and up. This class used to be called Formula A and has changed since January 2007 when CIK - FIA decided to replace the 100 cc water-cooled two-stroke engines with 125 cc Touch-and-Go (TaG) water-cooled two-stroke engines (KF type). The engines produce 40 hp (30 kW). KF1 class karts use hand-operated front brakes. The front brakes are activated by

150-415: A power-valve system . The valves are normally in or around the exhaust ports. They work in one of two ways; either they alter the exhaust port by closing off the top part of the port, which alters port timing, such as Rotax R.A.V.E, Yamaha YPVS, Honda RC-Valve, Kawasaki K.I.P.S., Cagiva C.T.S., or Suzuki AETC systems, or by altering the volume of the exhaust, which changes the resonant frequency of

225-421: A rotary valve is that it enables the two-stroke engine's intake timing to be asymmetrical, which is not possible with piston-port type engines. The piston-port type engine's intake timing opens and closes before and after top dead center at the same crank angle, making it symmetrical, whereas the rotary valve allows the opening to begin and close earlier. Rotary valve engines can be tailored to deliver power over

300-421: A DKW design that proved reasonably successful employing loop charging. The original SAAB 92 had a two-cylinder engine of comparatively low efficiency. At cruising speed, reflected-wave, exhaust-port blocking occurred at too low a frequency. Using the asymmetrical three-port exhaust manifold employed in the identical DKW engine improved fuel economy. The 750-cc standard engine produced 36 to 42 hp, depending on

375-525: A Lever. Chassis and engines must be approved by the CIK-FIA. Minimum weight is 160 kg (350 lb) with driver. Karts are equipped with an electric starter and clutch. The engine rpm is limited at 16,000 rpm. Top speed is around 140 km/h (87 mph), depending on circuits. As the Formula One of karting, KF1 has high costs and drivers typically spend $ 100,000 per year to compete. It

450-448: A crossflow engine) is always best and support is good. In some engines, the small end is offset to reduce thrust in the intended rotational direction and the forward face of the piston has been made thinner and lighter to compensate, but when running backward, this weaker forward face suffers increased mechanical stress it was not designed to resist. This can be avoided by the use of crossheads and also using thrust bearings to isolate

525-524: A few years to improve their skills before moving on to car racing , or they become professional kart racers and race in KF1 until they retire. Many successful racing drivers and all current F1 drivers started their careers in karts, and KF1 has been home to rivalries involving the likes of Lewis Hamilton , Nico Rosberg and Robert Kubica in the early 2000s, as well as Max Verstappen , Lando Norris and Nicklas Nielsen in more recent times. The class also played

600-565: A final which last 20 minutes or more, with a variety of point scoring calculations to determine the event's overall winner. Typical duration does not normally exceed 25 minutes. Here, speed and successful passing is of the most importance. It normally occurs in the format of qualifying, one to three heats and a final race for trophy positions. Sprint Racing in the United States and Canada are held at three primary levels, club racing (local races at purpose-built tracks), regional racing - like

675-592: A four-stroke engine, since their power stroke occurs twice as often. Two-stroke engines can also have fewer moving parts , and thus be cheaper to manufacture and weigh less. In countries and regions with stringent emissions regulation, two-stroke engines have been phased out in automotive and motorcycle uses. In regions where regulations are less stringent, small displacement two-stroke engines remain popular in mopeds and motorcycles. They are also used in power tools such as chainsaws and leaf blowers . The first commercial two-stroke engine involving cylinder compression

750-587: A leading role in the so-called golden era of karting in the 80s and 90s. There is a European KF1 Championship , a World Cup, and a World Championship , the sport's main event. Since 2016 the new generation of Original Karts (OK) machines have taken over from the old KF engines. Kart racing Kart racing or karting is a motorsport discipline using open-wheel , four-wheeled vehicles known as go-karts or shifter karts. They are usually raced on scaled-down circuits , although some professional kart races are also held on full-size motorsport circuits. Karting

825-474: A light and heavy category. Many people race worldwide in Spec series such as X30 125cc (a TaG class). As in other disciplines in motorsports, a license is required to drive a racing kart in competition. The licenses, issued by governing bodies, are provided by clubs or associations. Basic insurance coverage is usually included in the licence annual fee. In some countries, such as France , regulations require

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900-508: A motorsport in itself, it is one of the sports regulated by FIA (under the name of CIK ), permitting licensed racing for anyone from the age of 8 onward. In the United States, there is not as much FIA involvement; instead, many organizations regulate racing, such as the IKF ( International Kart Federation ), WKA ( World Karting Association ), KART (Karters of America Racing Triad), USPKS (United States Pro Karting Series) SKUSA (SuperKartsUSA). In

975-470: A patent in 1880 in Germany. The first truly practical two-stroke engine is attributed to Yorkshireman Alfred Angas Scott , who started producing twin-cylinder water-cooled motorcycles in 1908. Two-stroke gasoline engines with electrical spark ignition are particularly useful in lightweight or portable applications such as chainsaws and motorcycles. However, when weight and size are not an issue,

1050-412: A personal computer equipped with a data analysis software. More sophisticated systems allow for more information such as lateral and longitudinal acceleration ( g-force ), throttle position, steering wheel position and brake pressure. Kart racing is generally accepted as the most economical form of motorsport available on four wheels. As a free-time activity, it can be performed by almost anybody, and as

1125-449: A scavenging function. The units run in pairs, with the lower half of one piston charging an adjacent combustion chamber. The upper section of the piston still relies on total-loss lubrication, but the other engine parts are sump lubricated with cleanliness and reliability benefits. The mass of the piston is only about 20% more than a loop-scavenged engine's piston because skirt thicknesses can be less. Many modern two-stroke engines employ

1200-658: A similar system. Traditional flywheel magnetos (using contact-breaker points, but no external coil) worked equally well in reverse because the cam controlling the points is symmetrical, breaking contact before top dead center equally well whether running forward or backward. Reed-valve engines run backward just as well as piston-controlled porting, though rotary valve engines have asymmetrical inlet timing and do not run very well. Serious disadvantages exist for running many engines backward under load for any length of time, and some of these reasons are general, applying equally to both two-stroke and four-stroke engines. This disadvantage

1275-606: A stiffer chassis is preferable, while in wet or other poor traction conditions, a more flexible chassis may work better. Temperature of the track can also affect handling and may prompt additional chassis adjustments. The best chassis allow for stiffening bars at the rear, front and side to be added or removed according to race conditions. Braking is achieved by a disc brake mounted on the rear axle. Front disc brakes are used in most shifter kart classes and are increasingly popular in other classes; however, certain classes do not allow them. Shifter karts have dual master cylinders, one for

1350-421: A transmission in the automotive power train or drive train. The transmission can: Karts do not have a differential . The lack of a differential means that one rear tire must slide while cornering. This is achieved by designing the chassis so that the inside rear tire lifts up slightly when the kart turns the corner. This allows the tire to lose some of its grip and slide or lift off the ground completely. Power

1425-518: A turbocharger. Crankcase-compression two-stroke engines, such as common small gasoline-powered engines, are lubricated by a petroil mixture in a total-loss system . Oil is mixed in with their petrol fuel beforehand, in a fuel-to-oil ratio of around 32:1. This oil then forms emissions, either by being burned in the engine or as droplets in the exhaust, historically resulting in more exhaust emissions, particularly hydrocarbons, than four-stroke engines of comparable power output. The combined opening time of

1500-400: A wider speed range or higher power over a narrower speed range than either a piston-port or reed-valve engine. Where a portion of the rotary valve is a portion of the crankcase itself, of particular importance, no wear should be allowed to take place. In a cross-flow engine, the transfer and exhaust ports are on opposite sides of the cylinder, and a deflector on the top of the piston directs

1575-413: Is accepted in most cases where cost, weight, and size are major considerations. The problem comes about because in "forward" running, the major thrust face of the piston is on the back face of the cylinder, which in a two-stroke particularly, is the coolest and best-lubricated part. The forward face of the piston in a trunk engine is less well-suited to be the major thrust face, since it covers and uncovers

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1650-422: Is attributed to Scottish engineer Dugald Clerk , who patented his design in 1881. However, unlike most later two-stroke engines, his had a separate charging cylinder. The crankcase -scavenged engine, employing the area below the piston as a charging pump, is generally credited to Englishman Joseph Day . On 31 December 1879, German inventor Karl Benz produced a two-stroke gas engine, for which he received

1725-534: Is being phased out. Honda , for instance, ceased selling two-stroke off-road motorcycles in the United States in 2007, after abandoning road-going models considerably earlier. Due to their high power-to-weight ratio and ability to be used in any orientation, two-stroke engines are common in handheld outdoor power tools including leaf blowers , chainsaws , and string trimmers . Two-stroke diesel engines are found mostly in large industrial and marine applications, as well as some trucks and heavy machinery. Although

1800-574: Is common in on-road, off-road, and stationary two-stroke engines ( Detroit Diesel ), certain small marine two-stroke engines ( Gray Marine Motor Company , which adapted the Detroit Diesel Series 71 for marine use ), certain railroad two-stroke diesel locomotives ( Electro-Motive Diesel ) and large marine two-stroke main propulsion engines ( Wärtsilä ). Ported types are represented by the opposed piston design in which two pistons are in each cylinder, working in opposite directions such as

1875-481: Is commonly perceived as the stepping stone to the higher ranks of motorsports, with most Formula One drivers—including Ayrton Senna , Michael Schumacher , Fernando Alonso , Kimi Räikkönen , Lewis Hamilton , Sebastian Vettel , Nico Rosberg , and Max Verstappen —having begun their careers in karting. Karts vary widely in speed, and some (known as superkarts ) can reach speeds exceeding 160 kilometres per hour (100 mph), while recreational go-karts intended for

1950-963: Is held annually and lasts 24 hours with multiple classes participating. This event is hosted by the Prokart SSS Club near Johannesburg. The most popular class runs the Honda GX390 four-stroke engine, which is both affordable and durable, keeping running costs to a minimum. The Prokart Super Single Series, also known as Prokart SSS, has been running for more than 20 years and has proven to be a very popular entry platform for drivers of all ages who want to get into karting. Many clubs worldwide have taken on four-stroke endurance karting for this reason, since two-stroke karting can be very expensive. Speedway racing takes place on asphalt or clay oval tracks which are normally between 1/10-mile and 1/4-mile long. Tracks primarily consist of two straights and four left-turn corners, few tracks are symmetric and often

2025-488: Is needed to finance much practice, training and testing, team costs, chassis and engines, tires and parts, and traveling. Most teams in this category are factory teams or financed by chassis or engine manufacturers. Drivers typically compete in national competitions, then move into international racing in the KF3 or KF2 classes where they must finish in the top 34 to qualify to compete in KF1. Once in KF1, drivers either stay for

2100-507: Is no suspension , so chassis have to be flexible enough to work as a suspension and stiff enough not to break or give way on a turn. Kart chassis are classified in the United States as "Open", "Caged", "Straight" or "Offset". All Commission Internationale de Karting –, Fédération Internationale de l'Automobile –, or CIK-FIA-approved chassis are "Straight" and "Open". The stiffness of the chassis enables different handling characteristics for different circumstances. Typically, for dry conditions,

2175-852: Is one example. They have become the norm as the top international classes have switched to 125 cc clutch-equipped engines as of January 2007. Wheels and tires are much smaller than those used on a normal car. Wheels are made of magnesium alloy, aluminum , or composite materials . Tires can support cornering forces in excess of 2 g (20 m/s²), depending on chassis, engine, and motor setup . Some car tire manufacturers, such as MG Bridgestone , Dunlop , and Maxxis make tires for karts. There are also specific kart tire manufacturers, which include MG, Vega, MOJO, LeCont, Cobra, Hoosier and Burris. Similarly to other motorsports, kart tires have different types for use appropriate to track conditions: As in other motor sports, several data acquisition systems have been developed for kart racing. These systems allow

2250-432: Is that the two-stroke's crankcase is sealed and forms part of the induction process in gasoline and hot-bulb engines . Diesel two-strokes often add a Roots blower or piston pump for scavenging . The reed valve is a simple but highly effective form of check valve commonly fitted in the intake tract of the piston-controlled port. It allows asymmetric intake of the fuel charge, improving power and economy, while widening

2325-448: Is transmitted from the engine to the rear axle by a chain. Both engine and axle sprockets are removable. Their ratio must be adapted to the track configuration to obtain the most performance from the engine. In the early days, karts were direct drive, requiring push starts. The inconvenience of that configuration led to the centrifugal clutch for the club level classes. Dry centrifugal clutches are now used in many categories; Rotax Max

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2400-409: Is under every circumstance more efficient than cross-flow scavenging. In a uniflow engine, the mixture, or "charge air" in the case of a diesel, enters at one end of the cylinder controlled by the piston and the exhaust exits at the other end controlled by an exhaust valve or piston. The scavenging gas-flow is, therefore, in one direction only, hence the name uniflow. The design using exhaust valve(s)

2475-1124: The California ProKart Challenge , the Texas Sprint Racing Series , the Florida-based Sunshine Karting Championship Series , Route 66 Sprint Series in the Midwest, and the F-Series Gearup Challenge in the Northeast. National level karting takes place across North America in dedicated national series like the SKUSA Pro Tour Archived 22 July 2024 at the Wayback Machine , the USPKS Championship Series , WKA Manufacturers Cup and

2550-464: The Junkers Jumo 205 and Napier Deltic . The once-popular split-single design falls into this class, being effectively a folded uniflow. With advanced-angle exhaust timing, uniflow engines can be supercharged with a crankshaft-driven blower, either piston or Roots-type. The piston of this engine is "top-hat"-shaped; the upper section forms the regular cylinder, and the lower section performs

2625-806: The Karting World Championship , SKUSA SuperNats and all SKUSA Pro Tour, USPKS and ROK Cup USA Nationals take place in this format. Sprint racing can be held at a dedicated purpose-built track (most of which also rent club karts for family fun), and sprint races are also held at kart tracks that exist at many major auto sports complexes like Daytona International Speedway , Charlotte Motor Speedway , Pittsburgh International Race Complex , NOLA Motorsports Park in New Orleans, Homestead-Miami Speedway , and Road America . Sprint races are also held at temporary kart circuits that can be built in parking areas at large stadiums and casinos throughout

2700-579: The ROK Cup USA . The SKUSA Pro Tour championship is one of the most coveted, and the SKUSA SuperNats event held in Las Vegas annually is one of the largest kart races in the world, attracting drivers from every continent. The SKUSA SuperNats event has been run continuously for 25 years, and a SuperNats win is considered a legendary win in karting circles. The FIA championships, including

2775-512: The expansion chamber , such as the Suzuki SAEC and Honda V-TACS system. The result is an engine with better low-speed power without sacrificing high-speed power. However, as power valves are in the hot gas flow, they need regular maintenance to perform well. Direct injection has considerable advantages in two-stroke engines. In carburetted two-strokes, a major problem is a portion of the fuel/air mixture going directly out, unburned, through

2850-479: The oil reservoir does not depend on gravity. A number of mainstream automobile manufacturers have used two-stroke engines in the past, including the Swedish Saab , German manufacturers DKW , Auto-Union , VEB Sachsenring Automobilwerke Zwickau , VEB Automobilwerk Eisenach , and VEB Fahrzeug- und Jagdwaffenwerk , and Polish manufacturers FSO and FSM . The Japanese manufacturers Suzuki and Subaru did

2925-528: The 1960s due in no small way to the increased power afforded by loop scavenging. An additional benefit of loop scavenging was the piston could be made nearly flat or slightly domed, which allowed the piston to be appreciably lighter and stronger, and consequently to tolerate higher engine speeds. The "flat top" piston also has better thermal properties and is less prone to uneven heating, expansion, piston seizures, dimensional changes, and compression losses. SAAB built 750- and 850-cc three-cylinder engines based on

3000-407: The 1960s, especially for motorcycles, but for smaller or slower engines using direct injection, the deflector piston can still be an acceptable approach. This method of scavenging uses carefully shaped and positioned transfer ports to direct the flow of fresh mixture toward the combustion chamber as it enters the cylinder. The fuel/air mixture strikes the cylinder head , then follows the curvature of

3075-452: The German inventor of an early form in the mid-1920s, it became widely adopted in Germany country during the 1930s and spread further afield after World War II . Loop scavenging is the most common type of fuel/air mixture transfer used on modern two-stroke engines. Suzuki was one of the first manufacturers outside of Europe to adopt loop-scavenged, two-stroke engines. This operational feature

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3150-581: The MSA. Billed as the UK's first national karting league , the Elite Karting League also falls outside of MSA governance. In Australia, kart racing is administered by one of the following Karting bodies: Racing classes start at age 7 or 8 (5 in the United States with "Kid Karts") and generally run in 3-year age groupings or weight divisions until "senior" status is reached at age 15 or 16, depending on

3225-483: The UK, the Motor Sports Association (MSA) regulates most "owner driver" Karting. Some associations, such as NatSKA (National Schools Karting Association), organize race meetings throughout the country under the authority of the MSA. Various four-stroke "hire kart" series such as EPEC (European Prokart Endurance Championship) or BRKC (British Rental Kart Championship) fall outside the governance of

3300-489: The UK, the most celebrated karting series is the National karting series, also known as Super One . There are three types of Super One championships: Other UK National Championships include: Birel BirelART series UK: Cadet 60cc, Junior 100cc, Senior Light 125cc, Senior Heavy 125cc, British Indoor Karting Championship (BIKC) The BRKC is the UK's rental karting National championship, and the UK's official feeder series to

3375-749: The United States. Additionally, there are street races where races take place on city streets on temporary circuits like some of the IndyCar races. Endurance races last for an extended period, ranging from 30 minutes up to 24 hours or more, for one or more drivers. In general, consistency, reliability, and pit strategy is of greater importance than all out speed. Called "enduro" racing in the United States, most WKA and IKF sanctioned events typically last 30 minutes (sprint enduro) or 45 minutes (laydown enduro) and are run continuously without pit stops. Enduro events are held on full-size road racing circuits that are usually between 1.5 and 4 miles in length. As well as

3450-423: The bore diameter for reasonable piston ring life. Beyond this, the piston rings bulge into the exhaust port and wear quickly. A maximum 70% of bore width is possible in racing engines, where rings are changed every few races. Intake duration is between 120 and 160°. Transfer port time is set at a minimum of 26°. The strong, low-pressure pulse of a racing two-stroke expansion chamber can drop the pressure to -7 psi when

3525-459: The combustion chamber, and then is deflected downward. This not only prevents the fuel/air mixture from traveling directly out the exhaust port, but also creates a swirling turbulence which improves combustion efficiency , power, and economy. Usually, a piston deflector is not required, so this approach has a distinct advantage over the cross-flow scheme (above). Often referred to as "Schnuerle" (or "Schnürle") loop scavenging after Adolf Schnürle,

3600-453: The crankshaft commonly spins in the same axis and direction as do the wheels i.e. "forward". Some of the considerations discussed here apply to four-stroke engines (which cannot reverse their direction of rotation without considerable modification), almost all of which spin forward, too. It is also useful to note that the "front" and "back" faces of the piston are - respectively - the exhaust port and intake port sides of it, and are not to do with

3675-415: The cycle's potential for high thermodynamic efficiency makes it ideal for diesel compression ignition engines operating in large, weight-insensitive applications, such as marine propulsion , railway locomotives , and electricity generation . In a two-stroke engine, the exhaust gases transfer less heat to the cooling system than a four-stroke, which means more energy to drive the piston, and if present,

3750-411: The driver to monitor from a display fixed on the steering wheel some parameters such as RPM, timing of laps (including sectors), number of laps, best lap, cooling system temperature, exhaust gas temperature and sometimes speed or even gear for shifter karts. Some of those systems are able to record (logging) laps data from the sensors, allowing replay of an entire running session or/and direct download to

3825-416: The drivers to pass a medical exam each year. License classes differ between countries according to age groups or levels. Most of the time a Practice License can be easily obtained, while a Racing License might require a capability assessment. For their safety, kart drivers are required to wear proper equipment: Two-stroke engine Two-stroke engines often have a higher power-to-weight ratio than

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3900-400: The engine from end loads. Large two-stroke ship diesels are sometimes made to be reversible. Like four-stroke ship engines (some of which are also reversible), they use mechanically operated valves, so require additional camshaft mechanisms. These engines use crossheads to eliminate sidethrust on the piston and isolate the under-piston space from the crankcase. On top of other considerations,

3975-415: The exhaust port in the cylinder, the hottest part of the engine, where piston lubrication is at its most marginal. The front face of the piston is also more vulnerable since the exhaust port, the largest in the engine, is in the front wall of the cylinder. Piston skirts and rings risk being extruded into this port, so having them pressing hardest on the opposite wall (where there are only the transfer ports in

4050-409: The exhaust port, and direct injection effectively eliminates this problem. Two systems are in use: low-pressure air-assisted injection and high-pressure injection. Since the fuel does not pass through the crankcase, a separate source of lubrication is needed. For the purpose of this discussion, it is convenient to think in motorcycle terms, where the exhaust pipe faces into the cooling air stream, and

4125-488: The famous 24 Hours of Le Mans race for automobiles there is also a 24-hours event for karts which takes place at the kart circuit Alain Prost at Le Mans , France. This race has taken place since 1986 and its winners list include four-time Champ Car champion Sébastien Bourdais (in 1996). Endurance racing is also considered a more affordable way of getting into karting. In South Africa, the 24 Hours of Karting Festival race

4200-524: The fastest growing in the United States is Lo206. The general classes are 125cc Shifter, 100cc tag, 125cc tag and then the X30 equivalents of these karts. The CIK-FIA sanctions international championships in OK , OKJ , KZ1 , KZ2 and Superkart . These are regarded as the top-level classes of karting and are also raced in national championships worldwide. The World Championship is decided here. In May 2019 it held

4275-413: The fresh intake charge into the upper part of the cylinder, pushing the residual exhaust gas down the other side of the deflector and out the exhaust port. The deflector increases the piston's weight and exposed surface area, and the fact that it makes piston cooling and achieving an effective combustion chamber shape more difficult is why this design has been largely superseded by uniflow scavenging after

4350-745: The front and one for the rear, and are adjustable to allow for front/rear bias changes. Professionally raced karts typically weigh 165 to 175 lb (75 to 79 kg), complete without driver. Avanti , Tony Kart, Trulli , Birel , CRG , Gillard , Intrepid , Remo Racing , Kosmic, Zanardi or FA Kart and EKS are a few well-known examples of the many European manufacturers of race-quality chassis. Emmick, Coyote, Bandit, Shadow, MGM, Titan, PRC and Margay are American companies producing kart chassis. Racing karts mostly use small two-stroke or four-stroke engines; however, as of 2022, there has been small-scale adoption of electric motors in racing karts. Purpose of transmission: There are three reasons for having

4425-646: The general public may be limited to lower speeds. American Art Ingels is generally accepted to be the father of karting. A veteran hot rodder and a race car builder at Kurtis Kraft , he built the first kart in Southern California in 1956. Early karting events were held in the Rose Bowl Stadium car park. Instantly popular, Karting rapidly spread to other countries, and currently has a large following in Europe. The first kart manufacturer

4500-443: The intake and exhaust ports in some two-stroke designs can also allow some amount of unburned fuel vapors to exit in the exhaust stream. The high combustion temperatures of small, air-cooled engines may also produce NO x emissions. Two-stroke gasoline engines are preferred when mechanical simplicity, light weight, and high power-to-weight ratio are design priorities. By mixing oil with fuel, they can operate in any orientation as

4575-453: The international under-15 championship. The driver who finished first overall was Vlad Sputzki (Russia) followed by Daniel Smith (England) and then followed by Maximilien Blank (Australia) CIK-FIA categories: Non CIK-FIA categories: The Kart World Championship (or KWC) as opposed to the FIA's "Karting World Championship" uses 4-stroke rental karts and travels to a different country each year. In

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4650-475: The model year. The Monte Carlo Rally variant, 750-cc (with a filled crankshaft for higher base compression), generated 65 hp. An 850-cc version was available in the 1966 SAAB Sport (a standard trim model in comparison to the deluxe trim of the Monte Carlo). Base compression comprises a portion of the overall compression ratio of a two-stroke engine. Work published at SAE in 2012 points that loop scavenging

4725-399: The oil pump of a modern two-stroke may not work in reverse, in which case the engine suffers oil starvation within a short time. Running a motorcycle engine backward is relatively easy to initiate, and in rare cases, can be triggered by a back-fire. It is not advisable. Model airplane engines with reed valves can be mounted in either tractor or pusher configuration without needing to change

4800-487: The other - the inlet pipe having passage to the crankcase only when the two cutouts coincide. The crankshaft itself may form one of the members, as in most glow-plug model engines. In another version, the crank disc is arranged to be a close-clearance fit in the crankcase, and is provided with a cutout that lines up with an inlet passage in the crankcase wall at the appropriate time, as in Vespa motor scooters. The advantage of

4875-434: The piston covering and uncovering the ports as it moves up and down in the cylinder. In the 1970s, Yamaha worked out some basic principles for this system. They found that, in general, widening an exhaust port increases the power by the same amount as raising the port, but the power band does not narrow as it does when the port is raised. However, a mechanical limit exists to the width of a single exhaust port, at about 62% of

4950-440: The piston is at bottom dead center, and the transfer ports nearly wide open. One of the reasons for high fuel consumption in two-strokes is that some of the incoming pressurized fuel-air mixture is forced across the top of the piston, where it has a cooling action, and straight out the exhaust pipe. An expansion chamber with a strong reverse pulse stops this outgoing flow. A fundamental difference from typical four-stroke engines

5025-550: The power band. Such valves are widely used in motorcycle, ATV, and marine outboard engines. The intake pathway is opened and closed by a rotating member. A familiar type sometimes seen on small motorcycles is a slotted disk attached to the crankshaft , which covers and uncovers an opening in the end of the crankcase, allowing charge to enter during one portion of the cycle (called a disc valve). Another form of rotary inlet valve used on two-stroke engines employs two cylindrical members with suitable cutouts arranged to rotate one within

5100-466: The principles remain the same, the mechanical details of various two-stroke engines differ depending on the type. The design types vary according to the method of introducing the charge to the cylinder, the method of scavenging the cylinder (exchanging burnt exhaust for fresh mixture) and the method of exhausting the cylinder. Piston port is the simplest of the designs and the most common in small two-stroke engines. All functions are controlled solely by

5175-750: The rental Kart World Championship. NatSKA is a budget karting association set up for schools and youth groups in the UK, with 13 classes. In the United States, Dirt oval classes (which often use Briggs & Stratton industrial engines) are prominent in the Southeast and Midwest. In the West, European style sprint racing is much more common. In particular, 125cc shifter karts using Honda CR125 power units have gained tremendous popularity in recent years. In Australia, classes include Cadet (previously called Midget),Junior KA4, Junior KA3, X30, KZ2, Senior KA3, Senior TAG (Restricted and Unrestricted). Most classes run

5250-770: The same in the 1970s. Production of two-stroke cars ended in the 1980s in the West, due to increasingly stringent regulation of air pollution . Eastern Bloc countries continued until around 1991, with the Trabant and Wartburg in East Germany. Two-stroke engines are still found in a variety of small propulsion applications, such as outboard motors , small on- and off-road motorcycles , mopeds , motor scooters , motorized bicycles , tuk-tuks , snowmobiles , go-karts , RC cars , ultralight and model airplanes. Particularly in developed countries, pollution regulations have meant that their use for many of these applications

5325-424: The series. Typically, race formats are one of the following: Sprint racing takes place on dedicated kart circuits resembling small road courses, with left and right turns, hairpins, chicanes, and short and long straightaways. Tracks range from 1/4-mile (400 metres) to over 1 mile (1,600 metres) in length. The sprint format is a series of short-duration races, normally for a small number of laps, that qualify for

5400-540: The shape parallels that of an egg or a tri-oval . "Offset" kart chassis have been developed for precise handling and adjustability in left-turn-only racing competition taking place on oval and tri-oval tracks. Depending on the track material, different tires are used on the kart. Speedway kart races range in length from 4 laps for a trophy dash, to 20 laps for a main event. The two chief racing formats used in dirt speedway karting are heat races and timed laps qualification: There are many different classes in kart. One of

5475-520: The top or bottom of the piston. Regular gasoline two-stroke engines can run backward for short periods and under light load with little problem, and this has been used to provide a reversing facility in microcars , such as the Messerschmitt KR200 , that lacked reverse gearing. Where the vehicle has electric starting, the motor is turned off and restarted backward by turning the key in the opposite direction. Two-stroke golf carts have used

5550-567: Was an American company, Go Kart Manufacturing Co. (1957). In 1959, McCulloch was the first company to produce engines for karts. Its first engine, the McCulloch MC-10, was an adapted chainsaw two-stroke engine . Later, in the 1960s, motorcycle engines were also adapted for kart use, before dedicated manufacturers, especially in Italy ( IAME ), started to build engines for the sport. The chassis are made of chromoly tubing. There

5625-541: Was used in conjunction with the expansion chamber exhaust developed by German motorcycle manufacturer, MZ, and Walter Kaaden. Loop scavenging, disc valves, and expansion chambers worked in a highly coordinated way to significantly increase the power output of two-stroke engines, particularly from the Japanese manufacturers Suzuki, Yamaha, and Kawasaki. Suzuki and Yamaha enjoyed success in Grand Prix motorcycle racing in

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