Honda RC51 vs Aprilia Mille Factory vs Ducati 999S  

When you finally hit the meat of the powerband the 2004 Honda RC51 begins to show its muscles. A set of throttle bodies with two injectors per cylinder make the power deceiving until you hit triple digits in second gear. If there’s one thing that should be said over and over about this bike is that Honda makes riding a replica racer very easy, almost too easy.

The Mille Factory eventually loses some of its aggressiveness as the revs increase, which is exactly where the RC51 and 999 make up ground. The latter two continue to rev, and rev, and rev. But none of the three feel like they rev as high and continue to pull as hard as Ducati’s tour de force, the racing-inspired Testastretta engine.

With a liquid-cooled 998cc 90-degree V-Twin boasting a bore and stroke of 100 x 63.5mm and an 11.4:1 compression ratio, the 999S doesn’t appear much different than its competitors, but that’s not the way it feels on the bike. Despite it trailing the Honda at virtually all points on the dyno run, the 999S feels slightly more aggressive than the RC51 when the tach reads sub-7,000 rpm numbers. Moreover, it pulls hard all the way through the powerband. It doesn’t suddenly come on or drop off, but just pulls and continues to pull, and pull, and pull.

The 999’s Marelli electronic fuel injection uses 54mm throttle bodies to aid in production of some of the most accessible power available on a Twin. Whether the rider grabs a fistful of throttle or gently rolls it on, response is extremely silky and linear. On the street, a twist of the throttle on the 999S doesn’t scare the rider like the new crop of 1000cc inline fours, but if you get overzealous, you will get in trouble.

After taking a few days to get comfortable on the bikes, we hauled the trio over to Hansen’s BMW/Triumph/Ducati to see if our minds and bodies were translating the actual horsepower and torque accurately by strapping them down on a Dynojet chassis dyno. The majority of bets were placed on the aggressive Mille Factory, but a few of us were sure the Duc would emerge victorious.

The Ducati 999S went first and logged 119.5 horsepower at 10,200 rpm and 67.9 lb-ft. of torque at 8,100 rpm. The Aprilia finished close behind the Duc with 116.2 horsepower at 10,000 rpm with 67.6 lb-ft, of torque at 8,100. Then the RC51 ripped off the best peak power of the bunch, much to our surprise. Its peak of 120.2 horsepower is made at just 9,200 rpm. Further bolstering Honda’s stance as the most muscle-bound, the RC51 cranked out 70.5 lb-ft of torque at 8,200, besting its two competitors in both measures of power.

Moreover, the dyno charts indicate that Honda has a 4-horsepower advantage on the other two from the bottom and maintains that advantage for the majority of the rpm range. The RC’s only flaw is a large dip in its powerband from 4,000-5,000 rpm due to a similar EPA-driven lean condition, and that hampers its ability to pile on revs at low rpm. The Ducati almost matches the RC’s output between 9,700 rpm and redline, which occurs at 10,500 rpm for the Duc and 10,200 for the Honda.

2004 Honda RC51 Highs & Lows


  • Every component and piece of hardware functions beautifully
  • Most powerful Twin
  • Road going ameneties
  • $11,599 – way less than Aprilia or Ducati


  • Tall gearing saps power output
  • Lacks spectacular aesthetics
  • Brake fade after prolonged riding