The RC45's lineage stretches back to Honda's 1982 V4 engines introduced on the Magna and Sabre models, through the VFR750F RC24 of 1986, and the race-derived RC30 of 1988. By the early 1990s the RC30 was being outpaced by Ducati's V-twin machines, which benefited from a displacement advantage under the existing rules. Honda responded with a complete redesign using technology drawn from its factory RVF endurance racers.
The engine retained the V4 architecture and gear-driven camshafts of its predecessor but relocated the cam-drive mechanism from the centre of the engine to the end of the crankshaft. This reduced both the crankshaft and camshaft bearing count, cutting friction and allowing a slightly narrower engine package. The bore and stroke changed to 72 mm x 46 mm (from the RC30's 70 mm x 48.6 mm), giving a more over-square ratio capable of higher maximum revs while maintaining equivalent piston speed. Titanium connecting rods were again used, in a revised lighter and stronger format. Valve angles were tightened from 38 degrees to 26 degrees, straightening the intake ports and reducing flow turbulence.
The most visible technical advance over the RC30 was the adoption of Programmed Fuel Injection (PGM-FI), similar in design to the system used on Honda's NR750 road bike. Four 46 mm throttle bodies replaced the RC30's 38 mm constant-velocity carburettors. The ECU received input from eight sensors — crankshaft and camshaft position, air and coolant temperature, manifold absolute pressure, throttle position, barometric pressure, and battery voltage — enabling precise fuelling across a wide operating range. Ignition remained a separate system supplied by a different manufacturer. Extensive use of magnesium castings throughout the engine reduced overall weight.
US-specification engines were rated at 101 horsepower; European versions at 118 hp. In peak race trim by 1999, works RC45s were reported to produce over 190 hp.
The frame geometry was only modestly revised from the RC30: the steering angle was sharpened by 0.5 degrees, the wheelbase extended marginally, and the swingarm lengthened. Front brakes used 310 mm rotors — shared with the NR750 — with four-piston opposed calipers. The rear used a 220 mm rotor with a Nissin two-piston sliding caliper. Showa suspension was fitted front and rear. The gearbox retained the same gear ratios as the RC30, with only primary and secondary drive ratios altered. A sprag clutch of NR750 derivation replaced the RC30's unit, offering limited slip on overrun.
Despite Honda's full factory commitment to the programme, the RC45 initially struggled in WSB competition. Its sole championship success came in 1997, when American John Kocinski won the FIM Superbike World Championship riding the machine. In North American competition, Miguel Duhamel won the 1995 AMA Superbike title and the 1996 Daytona 200 on RC45-engined machines. Ben Bostrom took the 1998 AMA Superbike Championship. The RC45 also contributed to Honda's six Endurance FIM World Championship victories between 1984 and 1998 in the factory's RVF endurance programme. Michael Rutter won the 1998 Macau Grand Prix on the type. Jim Moodie lapped the Isle of Man TT Mountain Course at 124.45 mph from a standing start in 1999, clocking 18:11.4 seconds.
HRC heavily modified the bike during its competitive life, including revised exhaust systems and a return to a conventional two-sided swingarm for increased strength in sprint events, where the single-sided unit's additional weight was harder to justify.
The RC45 was retired from the World Superbike grid when Honda introduced the VTR1000R RC51 — a V-twin — for 2000, making use of the displacement advantage that had given Ducati its competitive edge throughout the decade. The RC45's rarity — estimated at around 20 surviving US-specification examples — and its status as a pure homologation racer have made it one of the most collectible Honda motorcycles. Its close relative, the RVF400R NC35, shared the same bodywork style with the exception of round headlights in place of the 750's units.