Honda RC51

Honda RC51 (RVT1000R)

          The aforementioned HRC design influence is reflected in the RC51 engine's architecture. As with the RC45 V-four before it, the 90-degree V-twin boasted gear-driven camshafts, an arrangement that provides more precise cam timing for better horsepower but is also very expensive to produce. Bore and stroke measurements were a then-very oversquare 100mm x 63.6mm configuration, although curiously with a relatively low compression ratio of only 10.8:1 (the Ducati 996 was pushing 11.5:1, while the Aprilia RSV Mille was at 11.4:1, and even the Suzuki TL1000R was bumping 11.7:1). With such a large bore, big valves could be installed, and Honda obliged with 40mm intakes and 34mm exhausts (for comparison, the Ducati 996 only had 36mm intakes/30mm exhausts). Even the engine fueling system was racing-spec; the Honda PGM-FI used a pair of 54mm throttle bodies-all of its twin-cylinder competition at the time of its introduction used smaller units-with 2 injectors per cylinder (all the others only had a single injector per jug). Due to the long-term reliability concerns of extended high-rpm running with a big V-twin (the cases undergo tremendous stress at five-figure rpm levels), the RC51 was saddled with a relatively low 10,000-rpm redline, with the rev-limiter stopping the party shortly thereafter at 10,200 rpm. In addition to the restrictive stock mufflers, the artificial rpm limitation kept the bike in showroom form down to about 118 horsepower at the rear tire.