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42-708: The Norton Manxman was a 650 cc vertical twin motorcycle manufactured by the British Norton Motorcycle Company at their Bracebridge St, Birmingham factory for export. The engine was an enlargement of the 600 cc engine used in the Model 99 Dominator . The Manxman was first shown at the November 1960 Earls Court Motorcycle Show and listed by the American importer, Berliner , in their catalogue from 1961 to October 1962 Berliner had asked for

84-450: A longitudinal engine orientation (i.e. with the crankshaft in line with the chassis) or a U-engine ( tandem twin ) where the cylinders are arranged longitudinally in the chassis (although the two crankshafts are actually oriented transversely). Compared with V-twin engines and flat-twin engines , straight-twins are more compact, a simpler design and cheaper to produce. Straight-twin engines can be prone to vibration, either because of

126-426: A 180 degree crankshaft and a balance shaft. Since 1993, most Honda straight-twin motorcycle engines use 180 degree crankshafts. Two-stroke engines typically use a 180 degree crankshaft, since this results in two evenly-spaced power strokes per revolution. The fundamental frequency of vibration is twice that of an equivalent single-cylinder engine; however, the amplitude is halved. Two-stroke engines that do not use

168-421: A 180 degree crankshaft include the 1972 Yankee . In an engine with a 270 degree crankshaft, one piston follows three quarters of a rotation behind the other. This results in an uneven firing interval where the second cylinder fires 270 degrees after the first, followed by a gap of 450 degrees until the first cylinder fires again. This is the same pattern as a 90 degree V-twin engine , and both configurations have

210-413: A 270 degree crankshaft can have a similar sound and feel to a V-twin engine with an uneven firing order. Longitudinal engine straight-twin motorcycles are less common; however, examples include the 1930–1938 Dresch Monobloc and the 1949–1956 Sunbeam S7 and S8 . This engine orientation allows for a motorcycle as narrow as a single-cylinder engine, which reduces the aerodynamic drag, especially for

252-476: A 360 degree crankshaft. Vibration was less of an issue for smaller engines, such as the 1965 Honda CB92 and 1979 Honda CM185 . Larger engines, such as the 1969 Yamaha XS 650 and 1972 Yamaha TX750 , often used balance shafts to reduce the vibration. The later 1978–1984 Honda CB250N/CB400N engines also used a 360 degree crankshaft, as does the 1989 Yamaha XTZ750 Super Ténéré . The 2008 BMW F series parallel-twin motorcycles also use 360 degree crankshafts, with

294-551: A balance shaft is often used to compensate for this. The secondary balance of a 270 degree engine is perfect; however, the configuration does result in an unbalanced rocking couple. The first production 270 degree straight-twin motorcycle engines were fitted to the 1996 Yamaha TRX850 and Yamaha TDM . Later examples include the 2009 Triumph Thunderbird , 2010 Norton Commando 961 , 2012 Honda NC700 series , 2014 Yamaha MT-07 , 2016 Triumph Thruxton 1200 and 2018 Royal Enfield Interceptor 650 & Continental GT . This architecture

336-442: A balance shaft to reduce the vibration. A 180 degree straight-twin engine has a secondary imbalance (similar to an inline-four engine); however, the lower reciprocating mass means that this often does not require treatment. A 180° crankshaft engine suffers fewer pumping losses than a 360° twin, because displacement of the crankcase is relatively unchanged as the pistons move. In the 1960s, Japanese motorcycle manufacturers favoured

378-413: A chain or belt drive a transverse engine is usually used, and with shaft drives a longitudinal engine. Longitudinal engines in motorcycles do have one disadvantage: the "tipping point" of the crankshaft tilts along the entire motorcycle to a greater or lesser degree when accelerating. This is partly resolved by having other components, such as the generator and the gearbox, rotate in the opposite direction to

420-430: A common crank pin for both connecting rods . Most vintage British straight-twin motorcycle engines (such as Triumph, BSA, Norton and Royal Enfield) had two main bearings . Beginning in the late 1950s, most Honda straight-twin engines had four main bearings. Subsequent straight-twin engines had four or occasionally three main bearings. The world's first production motorcycle, the 1894 Hildebrand & Wolfmüller used

462-422: A crankshaft angle of 360 degrees, since the two pistons are in the same direction (i.e. parallel to each other). "Vertical-twin" was used to describe engines with a crankshaft angle of 180 degrees, which causes the pistons to travel in opposite directions. The terms "straight-twin" and "inline-twin" were used more generically for any crankshaft angle. For motorcycles, "inline-twin" has sometimes referred to either

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504-419: A greater angle. In the late 1960s, GM divisions Oldsmobile and Cadillac had front-wheel drive models Toronado and Eldorado respectively, with a longitudinal V8 engine and an integrated automatic transmission and differential unit powering the front wheels. Honda and Toyota also offered front-wheel drive cars with longitudinal engines, namely Honda Vigor , Acura/Honda Legend/RL , and Toyota Tercel . This

546-406: A similar 'pulsing' exhaust sound as a result. The pistons in a 270 degree straight-twin engine are never both stationary at the same time (as per a 90 degree V-twin engine), thereby reducing the net momentum exchange between the crank and pistons during a full rotation. An imperfect primary balance is created in a 270 degree straight-twin engine, due to a combination of free force and rocking couple;

588-530: A small 2.5 US gal (9.5 L; 2.1 imp gal) petrol tank and high bars. The bike was finished in polychromatic blue with a red seat with white piping. Mudguards and the chaincase were chrome plated. Straight-twin engine Straight-twin engines are primarily used in motorcycles; other uses include automobiles, marine vessels, snowmobiles, jet skis , all-terrain vehicles, tractors and ultralight aircraft. Various different crankshaft configurations have been used for straight-twin engines, with

630-514: A straight-twin engine. The cylinders lay flat and forward-facing, with the pistons connected directly to the rear wheel using a locomotive-style connecting rod. In 1903, the Werner Motocyclette became the second production motorcycle model, using a straight-twin engine with vertical cylinders. The Werner engine uses cast-iron cylinders with integral heads, side valves and has a displacement of 500 cc. The 1938 Triumph Speed Twin

672-410: A third "vestigial" connecting rod (acting as a counterbalance) and a rev limit of 9,000 rpm to reduce vibrations. In 2009 Fiat launched Multiair inline twin car engines that use 360 degree crankshaft which relied on balance shafts to reduce the vibrations. In an engine with a 180 degree crankshaft, one piston rises as the other falls. In a four-stroke engine, the firing interval is uneven, with

714-415: Is as per a single-cylinder engine of equivalent reciprocating mass. Early engines attempted to reduce vibration through counterweights on the crankshaft; however, later methods also included balance shafts and a separate weighted connecting rod. Compared with a single-cylinder engine, the more frequent firing interval (360 degrees compared with 720 degrees) results in smoother running characteristics, despite

756-405: Is proving popular among manufacturers, which are upgrading models that were previously equipped with other engine types, such as the 2016 Honda Africa Twin (formerly a V-twin ), 2023 Honda Hornet (formerly an inline-4 ) or 2023 V-Strom 800 (the older design being equipped with a V-twin ). Each cylinder in a straight-twin engine has a separate crank pin , unlike V-twin engines which can use

798-474: Is usually used for rear-wheel drive cars, except for some Audi , SAAB , the Oldsmobile Toronado , and the 1967 Cadillac Eldorado equipped with longitudinal engines in front wheel drive. In front-wheel drive cars a transverse engine is usually used. Trucks often have longitudinal engines with rear-wheel drive. For motorcycles, the use of a particular type depends on the drive: in the case of

840-458: The 1961 Isle of Man TT Senior race, and achieved the first 100 mph (160 km/h) lap of the island on a pushrod machine. The head had downdraft inlet ports and wide-splayed exhaust ports to help cooling airflow over the head. A pair of Amal Monobloc carburettors were fitted. The new head, twin carbs, sports camshaft and 8.9:1 Compression ratio enabled the engine to produce a claimed 52 bhp (39 kW) at 6,800 rpm. Primary drive

882-588: The Hirth 2704 and Cuyuna 430-D. Purpose-built engines for ultralight aircraft include the Rotax 503 and Rotax 582 . Straight-twin engines are sometimes also used in large scale radio-controlled aircraft . Longitudinal engine In automotive engineering , a longitudinal engine is an internal combustion engine in which the crankshaft is oriented along the long axis of the vehicle , from front to back. See also: transverse engine This type of motor

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924-499: The 2001 Yamaha TMAX and the 2001 Honda Silver Wing . Straight-twin engines are also used in motocross sidecar racing. Many large British motorcycles from 1945 to the 1960s used a straight-twin transverse engine (i.e. oriented with the crankshaft perpendicular to the frame), such as the Triumph Bonneville and Norton Commando . This layout is well suited to air-cooling, since both cylinders receive equal airflow and

966-617: The 2008 Tata Nano . As of January 2024, petrol straight-twin engines used in production cars currently just include the Fiat TwinAir engine (used in various models from Fiat, Lancia and Alfa Romeo). The Piaggio Porter made use of a diesel straight-twin engine until 2020. Straight-twin engines have been often used as inboard motors , outboard motors and jet pump motors. In the early 20th century, gaff-rigged British fishing boats such as Morecambe Bay Prawners Lancashire Nobbys would sometimes retrofit an inboard engine, such as

1008-601: The American manufacturer Indian . In 1949, the AJS E-90 Porcupine won the 500  1949 Grand Prix World Championship , becoming the first and only straight-twin motorcycle to win the championship. This engine is one of few four-stroke straight-twins to use cylinders oriented horizontally rather than vertically. Since the 2000s, BMW and several Japanese manufacturers have continued to produce straight-twin engines, mostly for middleweight models. Several large scooters have also used straight-twin engines, such as

1050-660: The Amsterdam International Auto Show and went on sale in April that year as the 650SS . The Manxman's engine had its roots in the 1948 Bert Hopwood 500 cc design first used in the Model 7 Dominator . The air-cooled OHV vertical twin had been enlarged to 600 cc in September 1955 to satisfy the demands of the American market for larger engines. Norton's competitors were offering 650 cc machines so

1092-908: The Lister or the Kelvin E2 3.0 litre petrol-paraffin engine. From the 1950s, manufacturers of outboard motors had settled on the use of the basic inline engine design, cylinders stacked on top of each other with the crankshaft driving the propeller shaft . The Suzuki 15 outbound motor was introduced in 1989. Other uses include tractors (such as various John Deere models until 1960), snowmobiles , personal watercrafts , and all-terrain vehicles . Design variations include two-stroke, four-stroke, petrol, diesel, air-cooling , water-cooling , natural aspiration and turbocharging . Ultralight aircraft , single seat gyro-copters and small homebuilt aircraft have also used straight-twin engines, often using engines originally designed for snowmobiles such as

1134-483: The crankshaft. Most larger, "premium" vehicles use the longitudinal engine orientation in combination with rear wheel drive , because powerful engines such as the inline-6 and 90° big-bore V8 are usually too long to fit in a FF transverse engine bay. By contrast most mainstream modern vehicles use front wheel drive along with a transverse engine arrangement since they are usually equipped with inline-4 or V6 engines. While both layouts can be adapted for all-wheel drive ,

1176-436: The engine was again enlarged.to 89mm. with a all New crankcases were required for the longer stroke along with a new crankshaft that had larger crankpins and a wider flywheel, all-new cylinder barrels and pistons with short skirts and a;; new downdraft cylinder head for twin carbuerettors. (Anna J Dixon) A new alloy cylinder head was fitted that was derived from the 500 Domiracer that Tom Phillis had ridden to 3rd place in

1218-419: The exhaust can exit in the well-cooled location at the front of each cylinder. The transverse-engine straight-twin design has been largely replaced by V-twin engines ; however, the straight-twin design has the advantage of easier packaging of ancillaries (such as the air-filter, carburettor and ignition components), which also improves access to ancillaries for maintenance/repairs. A straight-twin engine using

1260-409: The irregular firing interval present in 180° crank engines or the large uncountered reciprocating mass in 360° crank engines. Inline-twins also suffer further from torsional torque reactions and vibration. The most common crankshaft configurations for straight-twin engines are 360 degrees, 180 degrees and 270 degrees. In an engine with a 360 degree crankshaft, both pistons move up and down at

1302-440: The longitudinal engine orientation has a more balanced weight distribution leading to superior handling characteristics, but is less efficient in terms of packaging and interior space. Cars with longitudinal engines usually have a smaller minimum turning circle than those with transverse engines. This is because there is more space to the sides of the engine, allowing deeper wheel arches so the front wheels are able to turn through

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1344-626: The model to be named Manxman although the twin had never been raced at the Isle of Man . 630 machines were produced in the first half of 1961 in 3 batches: first, 330 on 13 January, then 150 on 3 March and lastly 150 on 8 June. Of these, 99 were sent to Australia, 25 to Sweden, 1 to the Falkland Islands and the rest to the US. A European-styled version of the Manxman was shown in early 1962 at

1386-481: The most common being 360 degrees, 180 degrees and 270 degrees. The straight-twin layout is also referred to as "parallel-twin", "vertical-twin" and "inline-twin". Some of these terms originally had specific meanings relating to the crankshaft angle or engine orientation; however, they are often also used interchangeably. In the United Kingdom, the term "parallel-twin" is traditionally used for engines with

1428-619: The purpose of motorcycle racing. However, the main disadvantage for air-cooled engines is that the rear cylinder runs hotter than the front cylinder. Although two-cylinder engines are quite uncommon in cars, the straight-twin layout has been used for several automobile engines over time. The first known straight-twin engine was a variant of the Daimler Motors' Phoenix engine introduced in 1895; these engines were used in Panhard cars that year. Another early straight-twin engined car

1470-450: The same time. However, the firing interval is offset between cylinders, with one of the cylinders firing during the first crankshaft rotation and then the other cylinder in the following rotation. This set up results an even 360 degree firing interval unlike other crank configurations in inline twin engines. The 360 degree engines can use a single ignition system for both cylinders, using a wasted spark system. The imperfect primary balance

1512-435: The second cylinder firing 180 degrees after the first, followed by a gap of 540 degrees until the first cylinder fires again. The uneven firing interval causes vibrations and results in a 'lumpy' power delivery. A 180° engine also requires a separate ignition system for each cylinder. Perfect primary balance is possible with a 180 degree straight-twin engine; however, the design creates a rocking couple which requires use of

1554-439: The similar dynamic imbalance. From the 1930s, most British four-stroke straight-twin motorcycle engines used a 360 degree crankshaft, since this avoided the uneven intake pulsing of other configurations, thus preventing the need for twin carburettors. In the 1960s, even though Japanese motorcycles mostly switched to 180 degree crankshafts for engines sized from 250 to 500 cc, various smaller and larger engines continued to use

1596-408: The use of 180 degree crankshafts, since the increased smoothness allowed higher rpm and thus higher power outputs. For example, the 1966 Honda CB450 180 degree crankshaft engine has a similar power output to contemporary British 360 degree crankshaft engines, despite having a smaller displacement of 450 cc compared with 650 cc. Both the 1973 Yamaha TX500 and the 1977 Suzuki GS400 had

1638-501: Was a successful straight-twin motorcycle which also led to straight-twin engines becoming more widely used by other brands. The engine was designed by Edward Turner and Val Page , and was initially used in the 1933 Triumph 6/1 sidecar hauler (which won the International Six Days Trial silver medal and the 1933 Maudes Trophy ). During the development of the engine, it was found that a 360 degree crank angle

1680-572: Was better suited to the use of a single carburettor than a 180 degree crank angle. Following the trend created by the Triumph Speed Twin, the most common design used by British motorcycle manufacturers until the mid-1970s was a four-stroke straight-twin engine with a 360 degree crankshaft. The manufacturers producing these motorcycles included BSA , Norton , Triumph , Ariel , Matchless and AJS . Straight-twin engines were also produced by Italian and German manufacturers, along with

1722-465: Was by chain to a multiplate wet clutch and was enclosed in a pressed steel chaincase. The gearbox had 4 speeds. The combination of slimline featherbed frame and Roadholder forks used on the Dominators was carried forward to the Manxman. Alloy hubs containing 8 in (200 mm) front and 7 in (180 mm) rear drum brakes were fitted. Styled for the American market, the machine had

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1764-427: Was the 1898 Decauville Voiturelle , which used a pair of cylinders taken from a de Dion model mounted fore and aft and positioned below the seat. Straight-twin engines have been used in various small cars, such as the 1957 Fiat 500 , 1958 Subaru 360 , 1958 NSU Prinz , 1962 Mitsubishi Minica , 1967 Honda N360 , 1970 Honda Z600 , 1972 Fiat 126 , 1988 VAZ Oka , 1988 Dacia Lăstun , 1980 Daihatsu Cuore , and

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