In 1988 new rules in superbike racing allowed V-twin engines up to 999 cc to compete. Prior to the rules change, 750 cc four cylinder motorcycles were the dominant force in production based competition. During the first two years of the World Superbike championship, Honda won the series with their RC30, powered by a 750 cm3 V-4. In 1990, however, Raymond Roche secured Ducati's first world title aboard the Ducati 851. Throughout the next 11 years, Ducati would go on to win 8 World Superbike Championships with their V-twins (Honda won two and Kawasaki just one).[2]
Despite having an excellent engineering team and a significant amount of funding, Honda was unable to win consistently, particularly because of rival V-twins' displacement advantage over Honda's V-4. In 2000 Honda released the RC51, powered by a 998 cc liquid-cooled V-twin engine. That year, it won the World Superbike Championship with Colin Edwards riding for the Castrol team.
In 2001, Ducati regained the title but the RC51 was still a contender boasting superior reliability with comparable speed and power. The RC51 won again in its final year of factory-supported racing in World Superbike in 2002 and that same year also captured the AMA superbike title with Nicky Hayden. Honda had taken the lessons learned in the SP-1's first season, producing the SP-2 for 2002. A stronger, more rigid frame and swingarm were identical to the WSB race bike parts and a host of engine modifications boosted peak power by 3 kW (4 bhp) and cut weight by 5 kg (11 lb). Factory specifications for road going SP-2s (sourced from Honda) were 133 bhp with a top speed of 170 mph. The factory racing edition RC51 was said to put out 185 bhp or more.
Honda stopped official support for Superbike racing in 2003 (though various teams have had some factory support) and as Superbike rules changed to allow 1000 cc 4 cylinder bikes the RC51 was replaced by the CBR1000RR Fireblade as the Honda superbike racer.
