VT500 is a common name for the family of motorcycles sharing the Honda VT500 V-twin engine , with the cylinders set inline with the long-axis of the frame. Launched at the Cologne motorcycle show in September 1982, it was produced with various designations for different countries, such as Ascot , Shadow and Euro .
57-422: Conventional V twin engines often had the fore and aft cylinders set at 90-degrees to reduce the primary engine vibration, which in turn created a bulky, long engine requiring a long-wheelbase frame. Honda briefed their engineers to produce a compact, V twin engine with any angle narrower than 90 degrees, but leaving enough space between the cylinders to locate conventional carburetors with the airbox located under
114-420: A cold start . In order to ensure an adequate supply at all times, carburetors include a reservoir of fuel, called a "float chamber" or "float bowl". Fuel is delivered to the float chamber by a fuel pump . A floating inlet valve regulates the fuel entering the float chamber, assuring a constant level. Unlike in a fuel injected engine, the fuel system in a carbureted engine is not pressurized. For engines where
171-467: A venturi (aka "barrel"). Fuel is introduced into the air stream through small tubes (the main jets ) at the narrowest part of the venturi, where the air is at its highest speed. Downstream of the venturi is a throttle (usually in the form of a butterfly valve ) which is used to control the amount of air entering the carburetor. In a car, this throttle is connected to the vehicle's throttle pedal, which varies engine speed. At lesser throttle openings,
228-429: A flexible diaphragm on one side of the fuel chamber, connected to a needle valve which regulates the fuel entering the chamber. As the flowrate of the air in the chamber (controlled by the throttling valve/butterfly valve) decreases, the diaphragm moves inward (downward), which closes the needle valve to admit less fuel. As the flowrate of the air in the chamber increases, the diaphragm moves outward (upward) which opens
285-399: A low mileage example by as early as 1990. It was 390lbs (177 kg) equipped with front in-board disc and rear drum brakes sitting on 18" Comcast 3-spoke wheels front and back with a seat height of 31 inches and rearward footpegs. The headlight bucket leads the E's cosmetics being inclosed behind a "bikini-fairing" and small windshield, the rest of the bike's cosmetics are styled quite similarly to
342-440: A low-pressure area in the idle passage/port thus causing fuel to flow through the idle jet. The idle jet is set at some constant value by the carburetor manufacturer, thus flowing a specified amount of fuel. Many carburetors use an off-idle circuit, which includes an additional fuel jet which is briefly used as the throttle starts to open. This jet is located in a low-pressure area behind the throttle. The additional fuel it provides
399-464: A patent for a "gas or vapor engine", which ran on turpentine mixed with air. The design did not reach production. In 1875 German engineer Siegfried Marcus produced a car powered by the first petrol engine (which also debuted the first magneto ignition system). Karl Benz introduced his single-cylinder four-stroke powered Benz Patent-Motorwagen in 1885. All three of these engines used surface carburetors, which operated by moving air across
456-522: A property of air cavities known as Helmholtz resonance . Flow through the airbox is optimal at its resonance frequency , which depends on airbox volume and the inlet area and length of the snorkel. The resonance is typically chosen to be at a medium speed where torque otherwise drops, caused by valve timing overlap. This motorcycle, scooter or moped-related article is a stub . You can help Misplaced Pages by expanding it . Carburetor A carburetor (also spelled carburettor or carburetter )
513-433: A seat height of 31 inches and rearward footpegs. Appearance is sporty with a square tank (2.5 gallon (11 l) capacity) tapering to the long sleek seat with a gentle bump for the passenger tapering to the similarly shaped rear cowl. Beneath the seat is flat-tracker-style number plate side cover with a large decal stating "VT500 Ascot" emulating a number board/panel. The right side cover has a lower section painted black to emulate
570-406: A single carburetor shared between all of the cylinders, though some high-performance engines historically had multiple carburetors. The carburetor works on Bernoulli's principle : the static pressure of the intake air reduces at higher speeds, drawing more fuel into the airstream. In most cases (except for the accelerator pump ), the driver pressing the throttle pedal does not directly increase
627-437: Is a stub . You can help Misplaced Pages by expanding it . Airbox An airbox is an empty chamber on the inlet of most combustion engines. It collects air from outside and feeds it to the intake hoses of each cylinder. Older engines drew air directly from the surroundings into each individual carburetor . Modern engines instead draw air into an airbox, which is connected by individual hoses to each carburetor or directly to
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#1732782546400684-753: Is a device used by a gasoline internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to the intake air is through the Venturi tube in the main metering circuit, though various other components are also used to provide extra fuel or air in specific circumstances. Since the 1990s, carburetors have been largely replaced by fuel injection for cars and trucks, but carburetors are still used by some small engines (e.g. lawnmowers, generators, and concrete mixers) and motorcycles. In addition, they are still widely used on piston engine driven aircraft. Diesel engines have always used fuel injection instead of carburetors, as
741-420: Is a large wiring change in 84. No other mechanical differences exist outside the wiring update. The Shadow was offered world-wide from 1983 to 1986, though in a number of countries it was available through 1988. Riding on an Comcast's 18" front and 16" rear 5-spoke wheels with a 29-inch (735 mm) seat height, taller handle bars, and more forward-mounted foot controls this was the more popular cruiser alternative to
798-415: Is held shut by engine vacuum, is often used to do so. As the airflow through the carburetor increases the reduced manifold vacuum pulls the power valve open, allowing more fuel into the main metering circuit. In a two-stroke engine , the carburetor power valve operates in the opposite manner: in most circumstances the valve allows extra fuel into the engine, then at a certain engine RPM it closes to reduce
855-400: Is limited mainly by the fuel's viscosity so that the fuel flow tends to be proportional to the pressure difference. So jets sized for full power tend to starve the engine at lower speed and part throttle. Most commonly this has been corrected by using multiple jets. In SU and other (e.g. Zenith-Stromberg ) variable jet carburetors, it was corrected by varying the jet size. The orientation of
912-405: Is often used to prevent icing. This system consists of a secondary air intake which passes around the exhaust, in order to heat the air before it enters the carburetor. Typically, the system is operated by the pilot manually switching the intake air to travel via the heated intake path as required. The carburetor heat system reduces the power output (due to the lower density of heated air) and causes
969-664: Is spelled "carburetor" in American English and "carburettor" in British English . Colloquial abbreviations include carb in the UK and North America or Carby in Australia. Air from the atmosphere enters the carburetor (usually via an air cleaner ), has fuel added within the carburetor, passes into the inlet manifold , then through the inlet valve(s) , and finally into the combustion chamber . Most engines use
1026-399: Is used to compensate for the reduced vacuum that occurs when the throttle is opened, thus smoothing the transition from the idle circuit to the main metering circuit. In a four-stroke engine it is often desirable to provide extra fuel to the engine at high loads (to increase the power output and reduce engine knocking ). A 'power valve', which is a spring-loaded valve in the carburetor that
1083-541: The Carter Carburetor WCFB and the identical Rochester 4GC, introduced in various General Motors models for 1952. Oldsmobile referred the new carburetor as the "Quadri-Jet" (original spelling) while Buick called it the "Airpower". In the United States, carburetors were the common method of fuel delivery for most US-made gasoline (petrol) engines until the late 1980s, when fuel injection became
1140-414: The 1970s. EEC legislation required all vehicles sold and produced in member countries to have a catalytic converter after December 1992. This legislation had been in the pipeline for some time, with many cars becoming available with catalytic converters or fuel injection from around 1990. A significant concern for aircraft engines is the formation of ice inside the carburetor. The temperature of air within
1197-457: The V45 Sabre. The tank is very angular and pointed at the front edge then tapers with leg cut-outs to the thin seat with a taller passenger bump and lastly a gentle up-turn like a lip spoiler. Following the seat is a wrap-over grab bar mounted to a complex rear cowl (and extended rear fender) and angular taillight. The proceeding side covers are large but only the rear halves are painted to match
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#17327825464001254-468: The VT500 Euro & Ascot. The Shadow's hardware was all chrome and clear-coated aluminum typical of the other Honda cruisers of the time (Magnas & Shadow 750/700) so the only black parts on the bike are the frame, swingarm, radiator shroud, and engine (engine side covers became clear-coated aluminum in 1985). For all VT500 Shadows the tank (3 gallons (13.5 l)) was a large teardrop shape tapering to
1311-620: The VT500FT Ascot was available in Pearl Siren Blue (very dark blue with subtle but plentiful blue, purple, and red metallics) and Candy Bourgogne Red (medium/dark red with a bright metallic). In 1984 the VT500FT Ascot was available in Black (simply gloss black) and Metallic Red (very similar to the 83's "Candy Bourgogne Red" but slightly darker red base coat. Notable differences between the 1983 & 1984 VT500FT Ascots consist of
1368-413: The air speed through the venturi is insufficient to maintain the fuel flow, therefore the fuel is instead supplied by the carburetor's idle and off-idle circuits . At greater throttle openings, the speed of air passing through the venturi increases, which lowers the pressure of the air and draws more fuel into the airstream. At the same time, the reduced manifold vacuum results in less fuel flow through
1425-450: The barrels consist of "primary" barrel(s) used for lower load situations and secondary barrel(s) activating when required to provide additional air/fuel at higher loads. The primary and secondary venturi are often sized differently and incorporate different features to suit the situations in which they are used. Many four-barrel carburetors use two primary and two secondary barrels. A four-barrel design of two primary and two secondary barrels
1482-488: The body line of the fuel tank, the forward parts of the side covers are painted black to match the engine and frame. The Ascot was only available in North America and only for 1983 & 1984 overlapping the similarly named but entirely different 1982-1983 Honda FT500 Ascot. The 1983 VT500 Ascot was 390lbs (177 kg) equipped with front disc and rear drum brakes sitting on 18" Comcast 5-spoke wheels front and back with
1539-420: The carburetor can be reduced by up to 40 °C (72 °F), due to a combination of the reduced air pressure in the venturi and the latent heat of the evaporating fuel. The conditions during the descent to landing are particularly conducive to icing, since the engine is run at idle for a prolonged period with the throttle closed. Icing can also occur in cruise conditions at altitude. A carburetor heat system
1596-548: The carburetor is a key design consideration. Older engines used updraft carburetors, where the air enters from below the carburetor and exits through the top. From the late 1930s, downdraft carburetors become more commonly used (especially in the United States), along with side draft carburetors (especially in Europe). The main metering circuit consists of a pipe which reduces to a narrows before widening again, forming
1653-466: The choke based on the temperature of the engine's coolant liquid, an electrical resistance heater to do so, or air drawn through a tube connected to an engine exhaust source. A choke left closed after the engine has warmed up increases the engine's fuel consumption and exhaust gas emissions, and causes the engine to run rough and lack power due to an over-rich fuel mixture. However, excessive fuel can flood an engine and prevent it from starting. To remove
1710-408: The compression-based combustion of diesel requires the greater precision and pressure of fuel-injection. The name "carburetor" is derived from the verb carburet , which means "to combine with carbon", or, in particular, "to enrich a gas by combining it with carbon or hydrocarbons ". Thus a carburetor mixes intake air with hydrocarbon-based fuel, such as petrol or AutoGas (LPG). The name
1767-485: The engine in steady-state conditions, the inertia of fuel (being higher than that of air) causes a temporary shortfall as the throttle is opened. Therefore, an accelerator pump is often used to briefly provide extra fuel as the throttle is opened. When the driver presses the throttle pedal, a small piston or diaphragm pump injects extra fuel directly into the carburetor throat. The accelerator pump can also be used to "prime" an engine with extra fuel prior to attempting
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1824-418: The excess fuel, many carburetors with automatic chokes allow it to be held open (by manually, depressing the accelerator pedal to the floor and briefly holding it there while cranking the starter) to allow extra air into the engine until the excess fuel is cleared out. Another method used by carburetors to improve the operation of a cold engine is a fast idle cam , which is connected to the choke and prevents
1881-433: The float chamber is located close to the engine, heat from the engine (including for several hours after the engine is shut off) can cause the fuel to heat up to the point of vaporization. This causes air bubbles in the fuel (similar to the air bubbles that necessitate brake bleeding ), which prevents the flow of fuel and is known as 'vapor lock'. To avoid pressurizing the float chamber, vent tubes allow air to enter and exit
1938-407: The float chamber. These tubes usually extend into the carburetor throat, placed to prevent fuel from sloshing out of them into the carburetor. If an engine must be operated when the carburetor is not in an upright orientation (for example in a chainsaw or airplane), a float chamber and gravity activated float valve would not be suitable. Instead, a diaphragm chamber is typically used. This consists of
1995-414: The flow of air at the entrance to the carburetor. This increases the vacuum in the main metering circuit, causing more fuel to be supplied to the engine via the main jets. Prior to the late 1950s the choke was manually operated by the driver, often using a lever or knob on the dashboard . Since then, automatic chokes became more commonplace. These either use a bimetallic thermostat to automatically regulate
2052-426: The fuel entering the engine. Instead, the airflow through the carburetor increases, which in turn increases the amount of fuel drawn into the intake mixture. The main disadvantage of basing a carburetor's operation on Bernoulli's Principle is that being a fluid dynamic device, the pressure reduction in a venturi tends to be proportional to the square of the intake airspeed. The fuel jets are much smaller and fuel flow
2109-465: The fuel entering the engine. This is done in order to extend the engine's maximum RPM, since many two-stroke engines can temporarily achieve higher RPM with a leaner air-fuel ratio. This is not to be confused with the unrelated exhaust power valve arrangements used on two-stroke engines. A metering rod or step-up rod system is sometimes used as an alternative to a power valve in a four-stroke engine in order to supply extra fuel at high loads. One end of
2166-413: The fuel tank, to maintain a slim-profile without side-facing carburetors associated with some marques. The optimal design was found to be with the cylinder angle set at 52 degrees, but additionally having offset crankpins to achieve acceptable levels of vibration reduction without the need for additional balancing shafts which would have added weight and reduced power. The narrow-V engine was compact and at
2223-424: The idle and off-idle circuits. During cold weather fuel vaporizes less readily and tends to condense on the walls of the intake manifold, starving the cylinders of fuel and making cold starts difficult. Additional fuel is required (for a given amount of air) to start and run the engine until it warms up, provided by a choke valve . While the engine is warming up the choke valve is partially closed, restricting
2280-409: The intake air filter to be bypassed, therefore the system is only used when there is a risk of icing. If the engine is operating at idle RPM, another method to prevent icing is to periodically open the throttle, which increases the air temperature within the carburetor. Carburetor icing also occurs on other applications and various methods have been employed to solve this problem. On inline engines
2337-411: The intake air travelling through the carburetor is pressurized (such as where the carburetor is downstream of a supercharger ) the entire carburetor must be contained in an airtight pressurized box to operate. However, this is not necessary where the carburetor is upstream of the supercharger. Problems of fuel boiling and vapor lock can occur in carbureted engines, especially in hotter climates. Since
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2394-490: The intake and exhaust manifolds are on the same side of the head. Heat from the exhaust is used to warm the intake manifold and in turn the carburetor. On V configurations, exhaust gases were directed from one head through the intake cross over to the other head. One method for regulating the exhaust flow on the cross over for intake warming was a weighted eccentric butterfly valve called a heat riser that remained closed at idle and opened at higher exhaust flow. Some vehicles used
2451-426: The intake ports in fuel-injected engines, thus avoiding an extra intake manifold. The airbox allows the use of one air filter instead of multiples, reducing complexity. Developments arising from concerns about engine emissions during the late 1970s allow the airbox to collect pump gases from the crankcase and the tank air vent and re-feed them to the engine. Since the 1990s, engine designers also sought to exploit
2508-480: The needle valve to admit more fuel, allowing the engine to generate more power. A balanced state is reached which creates a steady fuel reservoir level, that remains constant in any orientation. Other components that have been used on carburetors include: The basic design for a carburetor consists of a single venturi (main metering circuit), though designs with two or four venturi (two-barrel and four-barrel carburetors respectively) are also quite commonplace. Typically
2565-484: The preferred method. One of the last motorsport users of carburetors was NASCAR, which switched to electronic fuel injection after the 2011 Sprint Cup series . NASCAR still uses the four-barrel carburetor in the NASCAR Xfinity Series . In Europe, carburetors were largely replaced by fuel injection in the late 1980s, although fuel injection had been increasingly used in luxury cars and sports cars since
2622-654: The properties of oscillating gas to improve performance. Many high-performance motorcycles have the airbox fed from funnels in the front of the bike, where increased pressure forces more air into the intake and thus improves power. Examples of this ram-air intake construction are the SRAD models of the Suzuki GSX-R750 , the Kawasaki Ninja ZX-6R or the BMW S1000RR . Secondly, designers exploit
2679-536: The rectifier regulator found on the left side exposed just below the left side cover. Exhaust is completely black chrome 2 into 1 system with a resonator/power-chamber above the center stand and a large cylindrical muffler with black chrome headshields covering all of the exhaust system's joints. Other cosmetic characteristics include a square headlight, "rounded-rectangle" turn signals, sporty horn cover, flat black trim, aluminum mounts with "speed holes", and black square gauges with aircraft-style gauge backgrounds. In 1983
2736-404: The rectifier-regulator found on the left side, the side covers are typically chrome with a full decal over the raised center section. The exhaust was a completely chrome 2 into 2 system utilizing a resonator/power-chamber above the centerstand. The VT500 is also the base for the later NTV, NT, VRX and XLV engines ranging from 400 to 750 cc. This motorcycle, scooter or moped-related article
2793-497: The rods is tapered, which sits in the main metering jets and acts as a valve for fuel flow in the jets. At high engine loads, the rods are lifted away from the jets (either mechanically or using manifold vacuum), increasing the volume of fuel can flow through the jet. These systems have been used by the Rochester Quadra jet and in the 1950s Carter carburetors. While the main metering circuit can adequately supply fuel to
2850-460: The same engine and intake system. Although most VT500s made 50hp some countries had access to 25hp versions for different tiers of operator's licenses. The Euro was offered from 1983 to 1988 primarily in Europe, it was not available in North America. The model was very popular with despatch riders, primarily for its low-maintenance shaft drive, flexible engine and slim frame. This made it hard to find
2907-547: The same though the final drive at the rear differential differed between each model. All the VT500 models were shaft drive but other variations/evolutions of the engine had a chain drive output instead. All VT500 Transmission Gear Ratios: Final Drive Ratios: The VT500s came in the form of a VT500E Euro, a VT500C Shadow, and a VT500FT Ascot from 1983 to 1988 depending on the model and region. Each differs from minor differences to major changes between each other but they all share
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#17327825464002964-418: The single-piece seat with an exaggerated scoop & bump for the driver and passenger respectively. Behind the seat is a mild aluminum grab-bar that corrals the taillight above the fender and flows halfway down the rear cowl/fender, the cowl/fender is painted to match the other bodywork. The side covers are an uneven parallelogram shape to match the frame and seat's bottom edge. The right side cover also emulates
3021-399: The throttle from closing fully while the choke is in operation. The resulting increase in idle speed provides a more stable idle for a cold engine (by better atomizing the cold fuel) and helps the engine warm up quicker. The system within a carburetor that meters fuel when the engine is running at low RPM. The idle circuit is generally activated by vacuum under the throttle plate, which causes
3078-453: The time was one of the lightest and narrowest, enabling a frame design offering good maneuverability. The engine is a 491cc liquid-cooled , V-twin , 4 stroke . The cylinders are splayed 52 degrees apart with a crankshaft that has its throws offset by 76 degrees, in order to achieve the lower primary vibration levels close to a 90-degree V-twin. The gear ratios among all the VT500s were
3135-549: The top of a vessel containing the fuel. The first float-fed carburetor design, which used an atomizer nozzle , was introduced by German engineers Wilhelm Maybach and Gottlieb Daimler in their 1885 Grandfather Clock engine . The Butler Petrol Cycle car—built in England in 1888—also used a float-fed carburetor. The first carburetor for a stationary engine was patented in 1893 by Hungarian engineers János Csonka and Donát Bánki . The first four-barrel carburetors were
3192-457: The wheels (83 had thick rim lips like VT500 Shadows while 84 had thin rim lips like VF700 Magnas), the foot controls (83 brake pedal & shifter were chrome while the 84 pedal & shifter were galvanized black), the tank decals (83 had 3 similar shades of grey on the Honda "wing" while 84 had 3 distinct shades of grey with very high metallic content), otherwise the only other noteworthy difference
3249-530: Was commonly used in V8 engines to conserve fuel at low engine speeds while still affording an adequate supply at high. The use of multiple carburetors (e.g., a carburetor for each cylinder or pair of cylinders) also results in the intake air being drawn through multiple venturi. Some high-performance engines have used multiple two-barrel or four-barrel carburetors, for example six two-barrel carburetors on Ferrari V12s. In 1826, American engineer Samuel Morey received
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