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28-552: The engine is an air-cooled , parallel twin , six-speed (in some markets, such as the UK, the first model was sold in five-speed form), reed valve -equipped intake tract two-stroke engine . The bike is usually referred to as a sport bike. All models were equipped with "Autolube" automatic oil injection, relieving the user from the need to mix gasoline and two-stroke oil . Rim sizes are 18" WM2 (1.85") front and 18" WM3 (2.15") rear, both being of chromed, wire spoked steel construction. In

56-412: A closed circuit carrying liquid coolant through channels in the engine block and cylinder head. A fluid in these channels absorbs heat and then flows to a heat exchanger or radiator where the coolant releases heat into the air (or raw water , in the case of marine engines ). Thus, while they are not ultimately cooled by the liquid, as the heat is exchanged with some other fluid like air, because of

84-430: A fluid is a function of its capacity and the difference in input and output temperatures. As the boiling point of water is reduced with lower pressure, and the water could not be efficiently pumped as steam, radiators had to have enough cooling power to account for the loss in cooling power as the aircraft climbed. The resulting radiators were quite large and caused a significant amount of aerodynamic drag . This placed

112-486: A great percentage of the heat generated, around 44%, escapes through the exhaust. Another 8% or so ends up in the oil , which itself has to be cooled in an oil cooler . This means less than half of the heat has to be removed through other systems. In an air-cooled engine, only about 12% of the heat flows out through the metal fins. Air cooled engines usually run noisier, however it provides more simplicity which gives benefits when it comes to servicing and part replacement and

140-440: A horizontal fashion as a Flat engine , while vertical Straight-four engine have been used. Examples of past air-cooled road vehicles, in roughly chronological order, include: During the 1920s and 30s there was a great debate in the aviation industry about the merits of air-cooled vs. liquid-cooled designs. At the beginning of this period, the liquid used for cooling was water at ambient pressure. The amount of heat carried away by

168-595: A performance bike manufacturer in India. There were two models for the Rajdoot 350 - High Torque and Low Torque. Compared to the Yamaha RD350B that made 39 bhp (29 kW) at the crankshaft, the 'High Torque' version made 30.5 bhp (22.7 kW) and the later 'Low Torque' made only 27 bhp (20 kW), the engine being detuned in the quest for better fuel economy. By the time the production ended in 1990,

196-411: Is 90 feet (27 m) long, and has a maximum of 109 rpm. Some inboard motors are freshwater cooled, while others have a raw water cooling system where water from the lake , river or sea is pumped by the engine to cool it. However, as seawater is corrosive, and can damage engine blocks and cylinder heads, some seagoing craft have engines which are indirectly cooled via heat exchanger in

224-475: Is a marine propulsion system for boats . As opposed to an outboard motor , where an engine is mounted outside the hull of the craft, an inboard motor is an engine enclosed within the hull of the boat, usually connected to a propulsion screw by a driveshaft . Marine diesel engines used in international shipping are the largest, most powerful engines ever produced. The first marine craft to utilize inboard motors were steam engines going back to 1805 and

252-418: Is usually cheaper to be maintained. Many motorcycles use air cooling for the sake of reducing weight and complexity. Few current production automobiles have air-cooled engines (such as Tatra 815 ), but historically it was common for many high-volume vehicles. The orientation of the engine cylinders is commonly found in either single-cylinder or coupled in groups of two, and cylinders are commonly oriented in

280-763: The Clermont and the Charlotte Dundas . Harbour tugs, and small steam launches had inboard steam engines. In the 1880s the naphtha engine made its appearance and a few boat engines appeared. Such engines had low power and high fuel consumption. The gasoline (petrol) engine pioneer Gottlieb Daimler and Maybach built a four-cycle boat engine and tested it in 1887 on the Neckar River. Sintz in America built several commercially available engines from 1893. Inboard motors may be of several types, suitable for

308-623: The 1900s. The first commercial production was by the New Way Motor Company of Lansing, Michigan, US. The company produced air-cooled engines in single and twin cylinders in both horizontal and vertical cylinder format. Subsequent to their initial production which was exported worldwide, other companies took up the advantages of this cooling method, especially in small portable engines. Applications include mowers, generators, outboard motors, pump sets, saw benches and auxiliary power plants and more. Marine engine An inboard motor

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336-690: The Light-Sport Aircraft ( LSA ) and ultralight aircraft market. Rotax uses a combination of air-cooled cylinders and liquid-cooled cylinder heads. Some small diesel engines, e.g. those made by Deutz AG and Lister Petter are air-cooled. Probably the only big Euro 5 truck air-cooled engine (V8 320 kW power 2100 N·m torque one) is being produced by Tatra . BOMAG part of the FAYAT group also utilizes an air cooled inline 6 cylinder motor, in many of their construction vehicles. Stationary or portable engines were commercially introduced early in

364-573: The Navy underwriting air-cooled engine development at Pratt & Whitney and Wright Aeronautical . Most other groups, especially in Europe where aircraft performance was rapidly improving, were more concerned with the issue of drag. While air-cooled designs were common on light aircraft and trainers, as well as some transport aircraft and bombers , liquid-cooled designs remained much more common for fighters and high-performance bombers. The drag issue

392-611: The UK, rim sizes were 1.60 front and 1.85 rear. Brakes are: single front disc brake and a rear drum brake, a combination described by Cycle Magazine as the best in its class. The frame dimensions of the street 350 are very similar to the Yamaha TZ 250 and TZ 350 series factory road race bikes, differing mainly in weight and front fork rake – the RD being ~27 degrees and the TZ being ~25 degrees. The frames appear similar, side by side, with

420-435: The bike was nearly 100% sourced in India, with very little Japanese parts content. Brakes are: 180mm dia drum brakes front internal expansion (twin leading type) and rear single internal expansion. The RD350 was the first sporting motorcycle built in India, and it still enjoys cult status, with many RD clubs around the country. Around 7000 were made at the end of 1990. Air-cooled engine Air-cooled engines rely on

448-868: The circulation of air directly over heat dissipation fins or hot areas of the engine to cool them in order to keep the engine within operating temperatures. Air-cooled designs are far simpler than their liquid-cooled counterparts, which require a separate radiator , coolant reservoir, piping and pumps. Air-cooled engines are widely seen in applications where weight or simplicity is the primary goal. Their simplicity makes them suited for uses in small applications like chainsaws and lawn mowers , as well as small generators and similar roles. These qualities also make them highly suitable for aviation use, where they are widely used in general aviation aircraft and as auxiliary power units on larger aircraft. Their simplicity, in particular, also makes them common on motorcycles . Most modern internal combustion engines are cooled by

476-575: The liquid-coolant circuit they are known as liquid-cooled . In contrast, heat generated by an air-cooled engine is released directly into the air. Typically this is facilitated with metal fins covering the outside of the Cylinder Head and cylinders which increase the surface area that air can act on. Air may be force fed with the use of a fan and shroud to achieve efficient cooling with high volumes of air or simply by natural air flow with well designed and angled fins. In all combustion engines,

504-542: The more refined and cleaner running RD400C in 1976, the "D" and "E" in 77–78 and the final model, the white 1979 RD400F. A licensed version of the RD350B was assembled in India between 1983–1990 by Escorts group under the brand name Rajdoot 350 . It did not repeat the success of the RD350B in the Indian market, which some attribute to a high purchase price and poor fuel efficiency . However, it established Rajdoot/Yamaha as

532-506: The much smaller radiators and less fluid in the system, the weight and drag of these designs was well below contemporary air-cooled designs. On a weight basis, these liquid-cooled designs offered as much as 30% better performance. In the late- and post-war era, the high-performance field quickly moved to jet engines . This took away the primary market for late-model liquid-cooled engines. Those roles that remained with piston power were mostly slower designs and civilian aircraft. In these roles,

560-434: The propulsion system may include many types, such as diesel , gas turbine , or even fossil-fuel or nuclear-generated steam. Some early models used coal for steam-driven ships. The largest engines in the world are marine diesel engines used to power supertankers and container ships . The Wärtsilä RT-flex96C produces 109,000 horsepower (81,000 kW), weighs 2,300 short tons (2,100 t), stands 44 feet (13 m) tall,

588-529: The radiator size by 50% compared to water cooled designs. The experiments were extremely successful and by 1932 the company had switched all future designs to this coolant. At the time, Union Carbide held a monopoly on the industrial process to make glycol, so it was initially used only in the US, with Allison Engines picking it up soon after. It was not until the mid-1930s that Rolls-Royce adopted it as supplies improved, converting all of their engines to glycol. With

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616-454: The simplicity and reduction in servicing needs is far more important than drag, and from the end of the war on almost all piston aviation engines have been air-cooled, with few exceptions. As of 2020 , most of the engines manufactured by Lycoming and Continental are used by major manufacturers of light aircraft Cirrus , Cessna and so on. Other engine manufactures using air-cooled engine technology are ULPower and Jabiru , more active in

644-549: The size of craft they are fitted to. Boats can use one cylinder to v12 engines, depending if they are used for racing or trolling . For pleasure craft, such as sailboats and speedboats, diesel, gasoline and electric engines are used. Many inboard motors are derivatives of automobile engines, known as marine automobile engines . The advent of the stern drive propulsion leg improved design so that auto engines could easily power boats. For larger craft, including ships, where outboard propulsion would in any case not be suitable,

672-458: The steam through tubes located just under the skin of the wings and fuselage, where the fast moving outside air condensed it back to water. While this concept was used on a number of record-setting aircraft in the late 1930s, it always proved impractical for production aircraft for a wide variety of reasons. In 1929, Curtiss began experiments replacing water with ethylene glycol in a Curtiss D-12 engine. Glycol could run up to 250 C and reduced

700-501: The street frame adorned with many brackets for the street equipment. The weight difference is substantial though, with the street-going RD frame weighing almost twice as much as the "TZ" roadrace race frame. The stock bike made 39 bhp (29 kW) (32 bhp (24 kW) at the back wheel) at 7500 rpm – very fast for the time. A contemporary of the RD is the Kawasaki H2 750cc Triple that produced 74 hp. The 350 evolved into

728-459: The two designs roughly equal in terms of power to drag, but the air-cooled designs were almost always lighter and simpler. In 1921, the US Navy , largely due to the efforts of Commander Bruce G. Leighton , decided that the simplicity of the air-cooled design would result in less maintenance workload, which was paramount given the limited working area of aircraft carriers . Leighton's efforts led to

756-590: The volume of water required and the size of the radiator by as much as 30%, which opened the way to a new generation of high-powered, relatively low-drag liquid cooled inline engines such as the Rolls-Royce Merlin and Daimler-Benz DB601 , which had an advantage over the unpressurized early versions of the Jumo 211 . This also led to development work attempting to eliminate the radiator entirely using evaporative cooling , allowing it to turn to steam and running

784-493: Was upset by the 1929 introduction of the NACA cowl , which greatly reduced the drag of air-cooled engines in spite of their larger frontal area, and the drag related to cooling was at this point largely even. In the late 1920s into the 1930s, a number of European companies introduced cooling system that kept the water under pressure allowed it to reach much higher temperatures without boiling, carrying away more heat and thus reducing

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