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The Honda RVF750R RC45 was a fully faired racing motorcycle created for
homologation Homologation (Greek ''homologeo'', ὁμολογέω, "to agree") is the granting of approval by an official authority. This may be a court of law, a government department, or an academic or professional body, any of which would normally work fr ...
purposes for the
Superbike World Championship Superbike World Championship (also known as WorldSBK, SBK, World Superbike, WSB, or WSBK) is a silhouette-class road racing series based on heavily modified production motorcycles, also known as superbike racing. The championship was founded i ...
by
Honda Racing Corporation Honda Racing Corporation (HRC) is a division of the Honda, Honda Motor Company formed in 1982. The company combines participation in Motorcycle racing, motorcycle races throughout the world with the development of racing machines. Its racing act ...
. The RVF750R was the successor to the VFR750R RC30 (not to be confused with the sport touring
VFR750F The Honda VFR750F is a motorcycle manufactured by Honda, Japanese automobile manufacturer Honda from 1986 to 1997. The model was initially displayed to the press after the 1985 Bol d'Or before it was officially introduced in 1986. The motorcy ...
). Like its predecessor, the RVF750R featured a
DOHC An overhead camshaft (OHC) engine is a piston engine where the camshaft is located in the cylinder head above the combustion chamber. This contrasts with earlier overhead valve engines (OHV), where the camshaft is located below the combustion c ...
liquid-cooled Liquid cooling refers to cooling by means of the convection or circulation of a liquid. Examples of liquid cooling technologies include: * Cooling by convection or circulation of coolant, including water cooling * Liquid cooling and ventilatio ...
V4
4-stroke A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directio ...
engine with gear driven cams and a single-sided
swingarm A swingarm, or "swinging arm" (UK), originally known as a swing fork or pivoted fork, is a single or double sided mechanical device which attaches the rear wheel of a motorcycle to its body, allowing it to pivot vertically. The main component of ...
, but unlike the RC30 it utilized
electronic fuel injection Manifold injection is a mixture formation system for internal combustion engines with external mixture formation. It is commonly used in engines with spark ignition that use petrol as fuel, such as the Otto engine, and the Wankel engine. In a mani ...
, in a setup very similar to the production 1992 NR750. The US spec engine had a 749.2cc capacity and was rated at 101
horsepower Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower. Two common definitions used today are the ...
; the European version was rated at 118 horsepower. A simple rewire modification to the PGM-FI box increased power in the US engine up to the 118 hp. It was manufactured from 1994 until 1995 and sold in limited numbers (the United States receiving the model for its first year only), followed by the VTR1000R SP-1 RC51 in 2000. Unlike the VFR750R RC30 and
VFR750F The Honda VFR750F is a motorcycle manufactured by Honda, Japanese automobile manufacturer Honda from 1986 to 1997. The model was initially displayed to the press after the 1985 Bol d'Or before it was officially introduced in 1986. The motorcy ...
from which the engine was originally derived the gear drive for the cams was moved from the centre of the engine in between the cylinders to the one side allowing a slightly narrower engine.


History

The RC45 has its roots from the original 1982 Honda V-45 V-four 750 engines introduced on the 1982 Honda Magna and Sabre models. Then in 1986, the 2nd generation V-four arrived in the form of the VFR750F (RC24), fixing the camshaft problem that plagued the original V-four and moving to gear driven cams. In 1988, the RC30 was born, loosely based on the RVF endurance racer, and this was used to contest the newly formed
Superbike World Championship Superbike World Championship (also known as WorldSBK, SBK, World Superbike, WSB, or WSBK) is a silhouette-class road racing series based on heavily modified production motorcycles, also known as superbike racing. The championship was founded i ...
. Only 300 were imported into the US for only one year, 1990. Then, in 1994, with the RC30 showing its age and being handily beaten by the Ducatis, Honda redesigned the RC30 using more of the technology from the RVF endurance racer and released the RC45 to much fanfare. Only 200 were manufactured worldwide and per AMA homologation rules 50 were imported into the US, with approximately 20 of them going to private race teams; it is estimated only 20 examples are left in the US. It is one of the rarest motorcycles produced by Honda. In its peak race form, in 1999, the RC45 made over 190 hp, with some calling it the best Superbike machine ever. Later in its career HRC heavily modified the bike to keep it competitive including new exhaust systems and switching back to a standard two-sided swingarm for increased strength on non-endurance bikes. The RC51 was released in 2000 to make use of the 250cc displacement advantage for V-twin motorcycles that allowed the Ducatis to be so competitive. The RC45 was shadowed with problems when first released on the World Superbike championship. This did not bode well with Honda, who entered the World Superbike championship with full factory support, not just privateer support that they gave to teams with the RC30.
Castrol Castrol is a British oil company that markets industrial and automotive lubricants, offering a wide range of oil, greases and similar products for most lubrication applications. The name ''Castrol'' was originally just the brand name for com ...
was the major sponsor of the RC45, and Honda came to win. The RC45 only won one World Superbike championship with American
John Kocinski John Kocinski (born March 20, 1968 in Little Rock, Arkansas) is a retired American Grand Prix motorcycle road racer whose successes include winning the 1990 250cc World Championship, and the 1997 Superbike World Championship title.FIM FIM may refer to: Organizations and companies * Fédération Internationale de Motocyclisme, the International Motorcycling Federation * Flint Institute of Music, in Michigan, United States * Fox Interactive Media, now News Corp. Digital Media * ...
Superbike World Championship. Jim Moodie from a standing start, on an RC45 Honda lapped in 18:11.4 seconds, 124.45 mph in the 1999
Isle of Man TT The Isle of Man TT or Tourist Trophy races are an annual motorcycle racing event run on the Isle of Man in May/June of most years since its inaugural race in 1907. The event is often called one of the most dangerous racing events in the world ...
.
Miguel Duhamel Miguel Duhamel (born May 26, 1967) is a Canadian former professional motorcycle racer. He is the son of Canadian Motorsport Hall of Fame member Yvon Duhamel. He is tied with Toni Elias for the fourth-winningest rider in the AMA Superbike series ...
won the 1995 US
AMA Superbike AMA Superbike Championship is an American motorcycle racing series that has been run every year beginning in 1976. For most of its existence it has been considered the premier motorcycle road racing series in the United States. It is sanctioned ...
and the 1996
Daytona 200 The Daytona 200 is an annual motorcycle road racing competition held in early spring at the Daytona International Speedway in Daytona Beach, Florida. The race was founded in 1937 when it was sanctioned by the American Motorcyclist Association ...
on an RC45. Miguel came in 2nd in 1996 and 2nd again 1997 on the RC45, then a season ending crash in 1998 injured his leg. However,
Ben Bostrom Benjamin Bostrom (born May 7, 1974) is an American former professional motorcycle racer. From 1995 to 2011 he competed in the AMA Superbike Championship, the World Superbike Championship and the MotoGP world championship.. Motorcycle racing car ...
won the 1998 AMA Superbike Championship on an RC45. The bike was used to win the
Endurance FIM World Championship The Endurance World Championship (FIM EWC) is the premier worldwide endurance championship in motorcycle road racing. The championship season consists of a series of endurance races (with a duration of six, eight, twelve or twenty-four hours) he ...
six times between 1984 and 1998.
Michael Rutter Sir Michael Llewellyn Rutter CBE FRS FRCP FRCPsych FMedSci (15 August 1933 – 23 October 2021) was the first person to be appointed professor of child psychiatry in the United Kingdom. He has been described as the "father of child psychol ...
won the 1998
Macau Grand Prix The Macau Grand Prix ( pt, Grande Prémio de Macau; ) is a motorsport road race for automobiles and motorcycles held annually in Macau. It is the only street circuit racing event in which both cars and motorcycles participate, and one of onl ...
. The RVF400R (NC35) closely resembles the RVF750R (RC45) with the exception of the headlights, which are large and round on the 750. If there was ever a bike that really had a reputation to live up to it was Honda’s RC45; after the success of the RC30, the RC45 really had to pull out all stops. Part of the success story of the RC30 was that it was a hand-built race bike that was available at a cost that many club racers could afford, so even though the number of victories in World Super Bike were only a few, (enough to win two titles though) The bike really excelled at a level where up until now only very expensive works bikes could have any chance of competing towards the front end of a race field. With the RC45, Honda drew on its extensive knowledge of racing the RC30 and factory RVF racers. Many engineering ideas were brought across to the RC45. Honda wanted to produce another no-expenses-spared race machine. Just a short time earlier the extremely complex NR750 had been released for road use, a bike which to this day is still considered an engineering masterpiece. Some of the technology of the NR750 was carried across to the RC45, These included its fuel-injection system, clutch, sprag clutch and even the 16-inch front wheel size. Some of the RC45's specifications: * V4 close firing order motor * Lightweight low friction pistons * Titanium conrods * Ceramic and graphite impregnated cylinder liners * Close ratio gearbox with undercut shift dogs * Separate air cooled oil heat exchanger * Many of the engine components were cast from magnesium to save weight * Cast upper and forged lower triple clamps * SHOWA front and rear suspension * 6.00 inch rear rim carrying a 190/50/17 tire


Differences from the RC30


Engine

Major development changes were made to the RC45’s engine, one of the first differences seen is the bore and stroke, which are much different from the
RC30 The Honda VFR750R, model code 'RC30', is a Motorcycle fairing, fully faired, solo-seat-only racing motorcycle created for homologation (motorsport), homologation purposes for the Superbike World Championship, World Superbike Championship by Honda ...
. The RC45 had a reduced stroke compared to the RC30, the RC30 having used a bore and stroke of 70 mm x 48.6 mm, whereas the RC45 was changed to a more over-square
stroke ratio In a reciprocating piston engine, the stroke ratio, defined by either bore/stroke ratio or stroke/bore ratio, is a term to describe the ratio between cylinder bore diameter and piston stroke length. This can be used for either an internal com ...
of 72 mm bore and 46 mm stroke. This allowed higher maximum engine revolutions than the RC30, whilst maintaining equal
piston speed The mean piston speed is the average speed of the piston in a reciprocating engine. It is a function of stroke and RPM. There is a factor of 2 in the equation to account for one stroke to occur in 1/2 of a crank revolution (or alternatively: tw ...
. Where the RC30 had used
roller bearings In mechanical engineering, a rolling-element bearing, also known as a rolling bearing, is a bearing (mechanical), bearing which carries a load by placing rolling elements (such as balls or rollers) between two concentric, Groove (engineering), g ...
on the camshafts, the RC45 used more conventional plain bearings. The RC30 had used a piston with one compression ring and oil control ring to reduce friction. This was very effective for racing but resulted in increased oil consumption in the road-going bikes. The RC45 changed to the more conventional two compression ring system, also with an oil control ring. Low-friction
piston ring A piston ring is a metallic split ring that is attached to the outer diameter of a piston in an internal combustion engine or steam engine. The main functions of piston rings in engines are: # Sealing the combustion chamber so that there is mini ...
materials and a molybdenum-disulphide coating on smaller piston skirts were used to reduce internal friction. A significant engine architecture difference between the RC30 and RC45 was the change from centre gear-drive mechanism to crank-camshaft drive, located on the end of the
crankshaft A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting ...
(first seen in the NR750). This reduced the number of crankshaft bearings by one, and camshaft bearings by four, with an associated reduction in friction. The RC45 also followed the RC30 in using
titanium Titanium is a chemical element with the symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in ...
connecting rods in a revised format, made lighter and stronger, to help cope with the extra RPM the moving parts of a race engine were expected to see. Honda drastically altered the head castings, tightening the valve angle from the 38degrees of the RC30 to 26degrees in the RC45. By reducing the valve angle, they straightened the port, along with making it higher, thus reducing the turbulence generating ‘short turn’ of the cylinder head. Honda also made the intake ports shorter and utilised intake valves that were 2 mm larger in diameter. The exhaust ports were also modified with a higher port roof, which reduced flow restrictions. The exhaust valves were also larger than the RC30’s in diameter The most notable change of the RC45 when released was the use of Programmed Fuel Injection. Fuel injection had been used on bikes previously but these had either been rather antiquated analog computers or very simple digital units with a minimal number of sensors for input, which resulted in very crude fueling. The RC30 had used 38 mm constant velocity carburettors which, for road use are quite nice, maintaining a high air velocity across a wide rpm range, though were not as well suited for racing. The RC45 did away with carburetors and in their absence a brace of four 46 mm throttles were replaced, Honda now had the throttle area it needed to make big horsepower at high revolutions. The system Honda used on the RC45 was very similar to the system used on the NR750. Contrary to popular belief the RC45’s fuel injection is not like a 4-stage carburetor, rather it is a proper fuel only system. Honda kept the ignition system separate. The Honda system obtained information from the following sensors: crankshaft position sensor, camshaft position sensor, air temperature sensor, coolant temperature sensor, manifold absolute pressure sensor, throttle position sensor, barometric sensor and battery voltage. With all of these sensors relaying information to the ECU, Honda could have quite easily incorporated the ignition control unit. The reason that they had not came down to the supplier of parts: they had different manufacturers supplying the ecu and cdi units. Regardless, it allowed the use of very large throttle plates seamlessly over a very wide engine operating range. The engine of the RC45 also used many magnesium castings, as of rather recently, it has become quite common to see fuel injection and magnesium engine parts on motorcycles, though in the early-to-mid 1990s this was expensive and incredibly innovative.


Gearbox

The gearbox differed little from the RC30’s; in fact, it even had the same gear ratios with only the primary and secondary ratios changed. The one-way sprag clutch was also carried over from the RC30 but was of NR750 design. This sprag clutch was a forerunner to today’s slipper clutches affording a slight amount of slip on overrun in the attempt to stop the back wheel from locking. The clutch plates were also from the NR750 and were much larger in diameter compared to the ones used in the RC30. The first gear was so tall that the increase in clutch plate diameter improved their longevity. All gears in the RC45’s gearbox were undercut to reduce the chance of a gear disengaging.


Brakes

The front brake rotors of the RC45 were 310 mm in diameter and are actually the same rotors and hats as used on the NR750. A four piston two piece opposed piston
caliper A caliper (British spelling also calliper, or in plurale tantum sense a pair of calipers) is a device used to measure the dimensions of an object. Many types of calipers permit reading out a measurement on a ruled scale, a dial, or a digital dis ...
was used along with asbestos-free pads. The rear brake used a 220 mm rotor and Nissin two piston sliding caliper also fitted with asbestos-free pads. This caliper was used on many different Hondas including the RC45’s little brother, the NC35 RVF400. There is nothing special about the brakes other than they were adequate for the time; many have later installed Brembo brakes or if the budget doesn’t stretch that far, the excellent Nissin caliper used on the 954 Fireblade and SP-1 VTR1000 can be bolted straight up with a marked improvement in braking response and feel.


Frame

The dimensions of the machine were little changed from the RC30: the steering angle was sharpened by 0.5 degree, the wheelbase was increased a few mm, the swing arm was lengthened slightly, and the front height was dropped about 4 mm. The major change was the placement of the motor in the frame. This has over the years sparked many debates, with some saying the motor was too far forward and others saying that the motor was too far back. It appears that Honda set out to build an all out race bike then made a few compromises to make it road usable. {{Honda motorcycles (1990s) RVF750 RC45