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91-569: Ducati abandoned the Grand Prix racing scene at the start of the 1970s. For many years the 500 class was essentially a class for two-stroke motorcycles, an engineering technology that was far removed from the four-stroke road-going machines sold by Ducati. Technical rules changed in 2002, giving priority to four-stroke machinery and turning the 500 class of World Road Racing into the MotoGP Championship. This convinced Ducati to make

182-415: 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

273-421: 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

364-421: 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

455-448: 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

546-472: A departure from Ducati's traditional steel trellis chassis. Although carbon fibre chassis were tried in mid 1980s, currently no other MotoGP racing team uses them. On January 15, 2010, Ducati introduced the GP10 for the 2010 MotoGP season. Development concentrated on improving engine longevity, to keep within new engine restrictions, and rideability. Most notably, the GP10 makes use of a big-bang firing order for

637-425: A difference in collarbone length between age groups 18–20 and 21–25 of about 6 and 5 mm (0.24 and 0.20 in) for males and females respectively. The left clavicle is usually longer and weaker than the right clavicle. The collarbones are sometimes partly or completely absent in cleidocranial dysostosis . The levator claviculae muscle , present in 2–3% of people, originates on the transverse processes of

728-410: A high shoulder position similar to that in modern humans . In dinosaurs , the main bones of the pectoral girdle were the scapula (shoulder blade) and the coracoid , both of which directly articulated with the clavicle. The clavicle was present in saurischian dinosaurs but largely absent in ornithischian dinosaurs. The place on the scapula where it articulated with the humerus (upper bone of

819-430: A mass of cancellous bone surrounded by a compact bone shell. The cancellous bone forms via two ossification centres , one medial and one lateral, which fuse later on. The compact forms as the layer of fascia covering the bone stimulate the ossification of adjacent tissue. The resulting compact bone is known as a periosteal collar. The collarbone has a medullary cavity ( marrow cavity ) in its medial two-thirds. It

910-485: A much-awaited return to the track in the new MotoGP class. Ducati history is classically based on 90° V-twin (or L-twin) engines, using desmodromic valve technology. Initially, Ducati considered the possibility of creating a MotoGP 'super-twin', taking advantage of the MotoGP regulations that give twin-cylinder machines a considerable weight reduction over four, five or six-cylinder bikes. However, analysis indicated that

1001-470: 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,

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1092-449: 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

1183-540: A second advantage over the next fastest 800 cc bike, a Honda ridden by Dani Pedrosa . MotoGP's 800 cc era officially began with the first race of the 2007 MotoGP season, at the Losail International Circuit in Qatar . Casey Stoner won the race on the new GP7. The bike had a clear top speed advantage over the rest of the grid, due to its higher output motor. A new track record was set on

1274-658: 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

1365-518: 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

1456-523: A twin-cylinder engine would not have been able to produce the required amount of power, without excessively increasing the number of revs. A twin would have had to rev at over 17,000 rpm, but this would require a very short stroke and a very large bore, as a result producing possible combustion problems. The basis of the Desmosedici engine design is a V4 configuration; essentially two classic V-twins mounted side-by-side, with two-cylinder stroking at

1547-400: 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

1638-421: Is a type of internal combustion engine that completes a power cycle with two strokes of the piston (one up and one down movement) in one revolution of the crankshaft. (A four-stroke engine requires four strokes of the piston to complete a power cycle, in two crankshaft revolutions.) In a two-stroke engine, the end of the combustion stroke and the beginning of the compression stroke happen simultaneously, with

1729-413: 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

1820-416: Is associated with the pectoral fin ; they also have a bone called the cleithrum . In such fish, the paired clavicles run behind and below the gills on each side, and are joined by a solid symphysis on the fish's underside. They are, however, absent in cartilaginous fish and in the vast majority of living bony fish, including all of the teleosts . The earliest tetrapods retained this arrangement, with

1911-422: 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

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2002-597: 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

2093-574: 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

2184-428: Is divided into two main regions, the medial region, and the lateral region. The medial region is also known as the sternal region, it is the longest clavicular region as it takes up two-thirds of the entire shaft. The lateral region is also known as the acromial region, it is both the widest clavicular region and thinnest clavicular region. The lateral region of the shaft has two borders and two surfaces. The collarbone

2275-404: Is made up of spongy cancellous bone with a shell of compact bone . It is a dermal bone derived from elements originally attached to the skull. The shape of the clavicle varies more than most other long bones. It is occasionally pierced by a branch of the supraclavicular nerve . In males the clavicle is usually longer and larger than in females. A study measuring 748 males and 252 females saw

2366-432: 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

2457-415: Is the first bone to begin the process of ossification (laying down of minerals onto a preformed matrix) during development of the embryo , during the fifth and sixth weeks of gestation . However, it is one of the last bones to finish ossification at about 21–25 years of age. Its lateral end is formed by intramembranous ossification while medially it is formed by endochondral ossification . It consists of

2548-446: Is the most commonly fractured bone. It can easily be fractured by impacts to the shoulder from the force of falling on outstretched arms or by a direct hit. The collarbone is a thin doubly curved long bone that connects the arm to the trunk of the body. Located directly above the first rib , it acts as a strut to keep the scapula in place so that the arm can hang freely. At its rounded medial end (sternal end), it articulates with

2639-409: 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)

2730-525: The 2024 Aragon motorcycle Grand Prix . ( key ) (results in bold indicate pole position; results in italics indicate fastest lap) * Season still in progress. Being his final MotoGP race, Capirossi switched numbers for Valencia as a memorial to his fallen countryman Marco Simoncelli , killed at Sepang , by racing with No. 58 that Simoncelli used, instead of his normal No. 65. He was still shown as No. 65 in official timing documentation. Two-stroke A two-stroke (or two-stroke cycle ) engine

2821-464: 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

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2912-405: The coracoid process ). These surface features are attachment sites for muscles and ligaments of the shoulder. It can be divided into three parts: medial end, lateral end, and shaft. The medial end is also known as the sternal end. It is quadrangular and articulates with the clavicular notch of the manubrium of the sternum to form the sternoclavicular joint . The articular surface extends to

3003-512: 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

3094-401: The gallbladder which is between the mid-clavicular line and the transpyloric plane . Clavicle fractures (colloquially, a broken collarbone) occur as a result of injury or trauma. The most common type of fractures occur when a person falls horizontally on the shoulder or with an outstretched hand. A direct hit to the collarbone will also cause a break. In most cases, the direct hit occurs from

3185-426: The manubrium of the sternum (breastbone) at the sternoclavicular joint . At its flattened lateral end (acromial end), it articulates with the acromion , a process of the scapula (shoulder blade), at the acromioclavicular joint . The rounded medial region (sternal region) of the shaft has a long curve laterally and anteriorly along two-thirds of the entire shaft. The flattened lateral region (acromial region) of

3276-479: 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

3367-528: 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

3458-407: 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

3549-722: The 2003 MotoGP championship. The Desmosedici GP3 quickly scored a series of results with Loris Capirossi, who stepped onto the podium in the opening round of the championship in Japan and won the GP Catalunya in Barcelona . Riders Capirossi finished fourth in the final championship standings and Bayliss sixth; while Ducati finished second overall in the Manufacturers' standings. In 2004 the Desmosedici GP4, again in

3640-462: The 2007 Australian Grand Prix. In the 17th round of the season at the newly resurfaced Sepang International Circuit in Malaysia, Dovizioso took his second pole of the year in wet conditions. At the start, he fell back to 4th while Iannone, who had qualified in 6th place, led briefly before falling to 2nd place. He stayed there till he crashed at Turn 9. That left Valentino Rossi with Dovizioso at

3731-559: The Desmosedici's development process from early testing to track debut and the project's evolution. In 2007, Ducati's pilot Casey Stoner, riding a Desmosedici, obtained Ducati's first MotoGP World Championship title. In early 2021, Ducati rider Johann Zarco set the highest trap speed record in competition practice on the Desmosedici. While still fully committed to Superbike racing, the Ducati Marlboro Team of Loris Capirossi and Troy Bayliss would compete in all rounds of

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3822-505: The GP7. Throughout 2007, Ducati tested a special fuel-saving clutch arrangement which disengaged the clutch during braking and reduced fuel consumption, however the arrangement was not incorporated in the GP8 as various advanced lubricants and fuels used with the GP8 are believed to provide comparable fuel savings, while decreasing internal engine friction and increasing maximum power. In race trim,

3913-503: The GP7. Its specifications were: 800 cc bike, double L-Twin motor (4 Cylinder Twin Pulse). Ducati started its project to build an 800 cc MotoGP bike extremely early and according to Ducati's racing chief Filippo Preziosi, by August 2006 Ducati had already built twenty 800 cc engines with various specifications. In addition, an early version of the bike was track tested for the first time during early May 2006. Public testing with

4004-488: The GP7. Second place contender and five time World champion, Yamaha's Valentino Rossi , realised that "unfortunately, there was too much difference between (our) bikes in the straight" and "Our Yamaha will never go as quick on a straight as the Ducati." These words turned out to be true, as the GP7 enjoyed a top speed advantage throughout the season, although the other manufacturers (Yamaha, Honda, Kawasaki and Suzuki ) closed

4095-452: 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

4186-552: The Italian skiing resort of Madonna di Campiglio , the GP6 is a lighter and more powerful version of the GP5. Involving better aerodynamics and a better fuel tank position, most importantly, although more powerful, the engine delivery was smoothened to make the bike more rideable. This made the bike slower on top speed, but quicker into, around and out of corners. The new rider with Capirossi

4277-517: The addition of a diamond-shaped interclavicle between the base of the clavicles, although this is not found in living amphibians . The cleithrum disappeared early in the evolution of reptiles , and is not found in any living amniotes , but the interclavicle is present in most modern reptiles, and also in monotremes . In modern forms, however, there are a number of variations from the primitive pattern. For example, crocodilians and salamanders lack clavicles altogether (although crocodilians do retain

4368-625: The back of Capirossi's bike. Both riders ended up injured and in the hospital, with Gibernau sustaining a broken collar bone , and both missed the Dutch Grand Prix at Assen . Capirossi returned at the British Grand Prix, while Gibernau was replaced by German Alex Hofmann for the Dutch Grand Prix, the British Grand Prix, and also the Czech Grand Prix after undergoing additional surgery. With Gibernau sidelined for

4459-519: The bike began at the Brno Track, where Loris Capirossi had won the day before riding the GP6, on the 21st of August. Capirossi's lap times on the prototype GP7 were only 1.4 seconds off his track record time set on the 990 cc GP6. Further testing of the GP7 in Motegi, Japan, revealed that the 800 cc machine could run faster laps than the higher-displacement 990 cc bikes, and held nearly

4550-484: The bike recorded an official top speed of 343.2 km/h (213.3 mph) at the 2008 Chinese motorcycle Grand Prix . The GP9 was Ducati's entry for the 2009 MotoGP World Championship. Ducati began testing it on track prior to May 2008. On 9 June 2008, Ducati publicly rolled out the Desmosedici GP9 for testing at Circuit de Catalunya . A distinctive feature of GP9 is its carbon fibre chassis, representing

4641-426: The body. The clavicle is the only long bone in the body that lies horizontally . Together with the shoulder blade, it makes up the shoulder girdle . It is a palpable bone and, in people who have less fat in this region, the location of the bone is clearly visible. It receives its name from Latin clavicula 'little key' because the bone rotates along its axis like a key when the shoulder is abducted . The clavicle

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4732-423: 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

4823-459: 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,

4914-453: 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

5005-415: 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,

5096-470: The development of new tyres and by the end of the season the Desmosedici became a competitive machine. Bridgestone found that hard tyres suited the bike more than softer tyres to create grip, allowing it to spin the rear wheel gave better control. Capirossi took two wins in the Grand Prix of Japan at Motegi and in the Malaysian GP at Sepang , while Checa scored a brace of podium finishes. Launched at

5187-400: 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,

5278-415: 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

5369-409: 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

5460-401: The final round of the season at Valencia following a collision with Casey Stoner, Ducati recalled Bayliss, who was recently crowned World Superbike champion. The race was won by Bayliss, his first MotoGP victory, with Capirossi taking second place for the first Ducati 1–2 finish. For 2007, MotoGP rules were changed to cap motors to a maximum displacement of 800 cc. In response, Ducati built

5551-605: The first time since the Desmosedici changed from the 990 cc to the 800 cc engine capacity. Ducati also redesigned the fairing, first seen at the 2009 Estoril round. On January 12, 2011, Ducati introduced the GP11 for the 2011 MotoGP season . The bike was raced by Valentino Rossi and Nicky Hayden . On March 19, 2012, Ducati unveiled the GP12 for the 2012 Grand Prix motorcycle racing season which incorporated new displacement standards of up to 1,000 cc in capacity. The bike

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5642-414: The form and function of the pectoral girdle. One exception is the clavicle of AL 333x6/9 attributed to Australopithecus afarensis which has a well-preserved sternal end. One interpretation of this specimen, based on the orientation of its lateral end and the position of the deltoid attachment area, suggests that this clavicle is distinct from those found in extant apes (including humans), and thus that

5733-413: 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

5824-480: The front and Jorge Lorenzo in a distant 3rd place. Rossi ran wide at turn 1 some laps later and fell back by around 1+ seconds per lap. 'DesmoDovi' held on for his first win with Ducati and his first win since his victory at Donington Park with the Repsol Honda Team in 2009. The Desmosedici RR is a road-legal version of the Desmosedici, first delivered in early 2008. These results are accurate up to

5915-462: The gap significantly by the end of the year. Stoner and his Bridgestone-shod Ducati proved to be the top combination in MotoGP and he won the world championship at Motegi , Japan, on September 23, 2007, four races before the end of the season. An update of the GP7 design, Ducati's entry for the 2008 MotoGP World Championship was tested first in February 2007. For purposes of avoiding chatter which

6006-476: The hands of Capirossi and Bayliss, underwent a series of major modifications. A large part of the season went by before the bike became competitive, but the season concluded with both riders on the podium. The GP5 version lined up for Ducati's third season in MotoGP, with Bayliss replaced by the Spanish rider Carlos Checa . Thanks to a collaboration agreement with Bridgestone , Ducati could finally contribute to

6097-417: The inferior aspect for articulation with the first costal cartilage . The lateral end is also known as the acromial end. It is flat from above downward. It bears a facet that articulates with the shoulder to form the acromioclavicular joint . The area surrounding the joint gives an attachment to the joint capsule. The anterior border is concave forward and the posterior border is convex backward. The shaft

6188-741: The intake and exhaust (or scavenging ) functions occurring at the same time. Two-stroke engines often have a higher power-to-weight ratio than 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

6279-443: 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

6370-467: The interclavicle), while in turtles , they form part of the armoured plastron . The interclavicle is absent in marsupials and placental mammals . In many mammals, the clavicles are also reduced, or even absent, to allow the scapula greater freedom of motion, which may be useful in fast-running animals. Though a number of fossil hominin (humans and chimpanzees) clavicles have been found, most of these are mere segments offering limited information on

6461-399: The lateral side towards the medial side of the bone. The most common site of fracture is the junction between the two curvatures of the bone, which is the weakest point. This results in the sternocleidomastoid muscle lifting the medial aspect superiorly, which can result in perforation of the overlying skin. The clavicle first appears as part of the skeleton in primitive bony fish , where it

6552-475: 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

6643-399: 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

6734-487: 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

6825-434: 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

6916-440: 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

7007-550: 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

7098-487: The previous year, albeit now coloured to match the predominantly white and red Desmosedici. In the 10th round of the season in Austria , Ducati dominated all sessions. Andrea Iannone and Andrea Dovizioso qualified 1st and 3rd respectively. In the race, Ducati used their lack of wheelies and extra power to stretch out a gap to Jorge Lorenzo after some laps. The two bikes stayed together, with Dovizioso in first for most of

7189-466: 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

7280-434: The propeller. These motors are compression ignition, so no ignition timing issues and little difference between running forward and running backward are seen. Collar bone The clavicle , collarbone , or keybone is a slender, S-shaped long bone approximately 6 inches (15 cm) long that serves as a strut between the shoulder blade and the sternum (breastbone). There are two clavicles, one on each side of

7371-413: The race. But Iannone out-braked him and took the lead into the penultimate corner of the last lap. The win was the first for Iannone in MotoGP and his first since Moto2 Italy 2012 . The win was the first for Ducati (and any other manufacturer than Honda or Yamaha ) since Casey Stoner won for the team in 2010 Australian Grand Prix. Dovizioso finished in 2nd place to mark the first Ducati 1–2 finish since

7462-821: 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

7553-542: The same time (also called Twin Pulse). With four valves per cylinder, the total number of valves is sixteen – Desmosedici means desmodromic distribution with sixteen valves shortened in Italian . Design had started in 2001, the bike was unveiled at the 2002 Italian GP at Mugello , for use in the following seasons MotoGP World Championship. Vittoriano Guareschi , the Ducati Corse test-rider, followed every phase of

7644-427: The shaft has an even larger posterior curve to articulate with the acromion of the scapula. The medial region is the longest clavicular region as it takes up two-thirds of the entire shaft. The lateral region is both the widest clavicular region and thinnest clavicular region. The lateral end has a rough inferior surface that bears a ridge, the trapezoid line , and a slight rounded projection, the conoid tubercle (above

7735-408: The shape of the human shoulder dates back to less than 3 to 4 million years ago . However, analyses of the clavicle in extant primates suggest that the low position of the scapula in humans is reflected mostly in the curvature of the medial portion of the clavicle rather than the lateral portion. This part of the bone is similar in A. afarensis and it is thus possible that this species had

7826-520: 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

7917-419: The upper cervical vertebrae and is inserted in the lateral half of the clavicle. The collarbone serves several functions: Muscles and ligaments that attach to the collarbone include: A vertical line drawn from the mid-clavicle called the mid-clavicular line is used as a reference in describing cardiac apex beat during medical examination. It is also useful for evaluating an enlarged liver, and for locating

8008-609: Was Spanish rider Sete Gibernau . After encouraging winter tests, the Desmosedici GP6 took its first win of 2006 in the opening GP at Jerez de la Frontera, Spain, followed by a podium in Qatar. Capirossi led the championship for a short while, but at the start of the Grand prix de Catalunya at Barcelona, Gibernau's bike collided with Capirossi's after Gibernau braked too late and compressed his brake lever further after impacting it on

8099-499: Was encountered on some occasions with GP7, the rigidity of the GP8's frame was altered, although further details of relevant modifications are not disclosed. In addition, in an attempt to reduce an effect described as "pumping", some modifications to the bike's suspension geometry were made. As with its predecessor the GP8 contains a four-cylinder 800 cc engine with desmodromic actuation of its 16 valves. The engine has improved mid-range response and top-end power compared to that of

8190-433: Was raced by Valentino Rossi and Nicky Hayden . The Desmosedici GP16 was unveiled in February 2016. It ran the first two pre-season tests with race riders Andrea Dovizioso and Andrea Iannone without a livery. Ducati's MotoGP boss Gigi Dall'Igna describes the 2016 Desmosedici as an "evolution" of its recent challengers. The GP16 was still the fastest bike in a straight line with its extra power. The winglets remained from

8281-482: 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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