With the homologation approval period for its limited-production RC45 coming to an end in '99, Honda surprisingly announced that it would be introducing a new liter-size V-twin superbike in its upcoming 2000 model lineup to run alongside the then-new CBR929RR inline-four superbike. With four-cylinder machines still limited to 750cc in superbike racing, it was an obvious sign that Honda was dumping the multi-cylinder route and looking to take on Ducati at its own twin-cylinder game. HRC (Honda Racing Corporation, the racing arm of Honda Japan) played a major role in the design of the new twin, which was designated the VTR1000 SP1 everywhere in the world except the U.S., where it was known as the RC51 (even though its actual model designation was RVT1000R).
In its first year, the Honda RC51 proved its performance potential by winning the '00 World Superbike title with Colin Edwards aboard. Meanwhile in the AMA Superbike series, a young Nicky Hayden just missed out on the title to Mat Mladin by a slim five points. Edwards grabbed another world title in '02, and Hayden would pick up a win in the Daytona 200 in his march to the '02 AMA Superbike championship.
The bike was an instant hit with sportbike fans. The RC51's booming exhaust note had a sound different than the Ducati twins, and surely unlike any other Japanese bike in production. The bike's HRC heritage could be seen throughout its design and was proudly displayed on the engine cases. And not only did Honda make a works racing replica machine, they offered it at a very affordable $9999. Compared to the very limited production RC45 ($27,000), this Honda was a bargain and they were snatched up across the country. Although import quantities couldn't quite be considered production-level, it's rumored that about 2000 were brought into the U.S.A. in the first year.
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.
The frame was built to withstand the rigors of Superbike racing so its construction was quite beefy and stiff right from the factory, though it was a bit heavy. With 24.5 degrees of rake and 100.5mm (3.96 inches) of trail, the steering geometry was obviously aimed at stability over agility when combined with the short 55.5-inch wheelbase. Honda claimed a dry weight of 432 pounds, but after filling it up with gas, it was more like 489 pounds, making it quite a bit heavier than you'd envision a sportbike to be. Nonetheless, it was competitive with the Aprilia RSV and the Ducati 996, its primary competition at the time (although it was about 50 pounds heavier than Honda's CBR929RR). The 999cc engine was rather thirsty, and its low 28-mpg average meant that even the 4.8-gallon fuel tank only guaranteed a 140-mile range at the most. Throttle response was not quite up to Honda standards on the 2000-01 models, with an abrupt response off closed throttle that would upset handling midcorner.
In '02, Honda released a new SP2 model that featured a host of upgrades, most of them directly from the race kit for the SP1 model. It made about five more horsepower, much of that due to the larger 62mm throttle bodies and redesigned cylinder head porting. Remapped fuel injection curves and finer 12-jet injectors helped eliminate the previous throttle response problem. Other major changes included sharper steering geometry, with the rake pulled back to 23.5 degrees and trail shortened to 94.6mm (3.7 inches), and each side radiator equipped with its own fan to address the overheating issues that plagued the SP1. The new swingarm was basically the SP1 race kit model, stretching the wheelbase by 16mm while adding rigidity and cutting weight in the process. The SP2 model had a taller (1.2 inches) windscreen developed from Colin Edwards' World Superbike mount, as well as redesigned mufflers for less weight. All told, the SP2 dropped about eight pounds in the process.
Those who spent time on both the SP1 and SP2 report that the differences were noticeable, with the sharper handling and better fueling the most apparent. While the Honda may not have been the sexiest bike ever produced, it does exude a certain purposeful look. Without trying too hard it looks like a race bike should.
The $9,999 retail price only lasted one year and by the time the 2001 models were released, the price had already bumped up to $10,999. In 2004 the price increased to $11,599 and then to $11,999 in 2006. In looking at the current NADA retail prices, one might notice that the RC has done better than the Honda one-liter CBRs. Currently the original SP1 models are showing a retail of $4500 moving up to $5260 for the '02 SP2. The last year of production (2006) shows a current retail of $8,825.
Since the annual production of this bike was fairly low, it did not attract the typical aftermarket supplier's attention when it came to go-fast goodies. This is where Dan Kyle of Kyle Racing (www.kyleusa.com) stepped into the RC51 aftermarket parts arena in a big way. Kyle has been around motorcycles and motorcycle racing since 1973 (those of you long-time motorcycle racing fans may recall Kyle being heavily involved with both Two Brothers Racing and Erion Racing in the AMA Superbike series), and was quick to see this need, establishing himself as a major supplier for the new Honda superbike.
Dan admits that the "RC51 may not be the fastest bike around the track, but the owner usually finishes the day with the biggest smile." We asked Dan about the popular modifications for the Honda and he stated that one of the first parts normally added to the bike is an aftermarket exhaust and a Power Commander. On the SP1, the fuel injection needed some help to smooth out the throttle response and the PC went a long way toward correcting that issue.
As for the exhaust system, Kyle says their extensive in-house testing has shown that very few if any of the full exhaust systems make any more power than the dual slip-ons offered by Sato and Moriwaki and each saves a total of 10-11 pounds. Other popular choices among riders include Erion, Jardine, and Akrapovic. While most of the 2-into-1 exhaust systems do offer slightly higher top end power, it comes at the expense of the midrange that v-twin riders enjoy. The use of high mount exhausts means the removal of the passenger pegs, so choose the correct setup based on your intended use of the bike.
Most tuners opted to leave the stock air filter but disconnected the internal "flapper valve" in the airbox, which was there for EPA noise emission reasons. By simply disconnecting the vacuum line feeding the flapper, it is left in the open position which helps remove a dip in the power curve at the 4500-5500 rpm range. Another popular trick is to defeat the factory "soft rev-limiter". In stock form, the soft limiter kicks in at 9000 rpm and then the hard limiter waits until 10,200 rpm. By allowing the bike to rev freely all the way to the hard limiter, the combined result of the exhaust and EFI tuning nets a nice 8-10 horsepower gain on top.
Perhaps the biggest improvements on the bike come in the suspension department. Although the bike came with a nice setup, according to Kyle it is a big compromise. Due to the fact that street bikes are set up for solo and dual riders, the suspension is quite progressive. If you are willing to set up your bike for one weight range, it allows you to optimize a suspension system that is much more linear. The most popular change is to add an Öhlins fork kit. Since the RC shares the same basic fork as the CBRs internally, there is a lot of data and parts available to set it up for most any rider. The Öhlins kit includes springs and internal re-valving and goes for about $650 from Kyle Racing.
On the rear, one of the least expensive fixes ($349) is to simply change the rear suspension link with one that is less progressive. Kyle Racing makes their own link and not only does it address the progressive nature of the suspension but it also raises the rear slightly which helps the RC turn a little better. Out of the box, the RC51 is very stable, but it also steers a little slow. An advantage of this design is that a steering damper is not an absolute requirement. Some riders have it but they do so mostly as an insurance policy, not a necessity.
Unfortunately the rear shock itself isn't the greatest (even the upgraded SP2 unit), with overly stiff high-speed compression damping rates that can't be adjusted out externally, and delving into the internals is a major hassle. Kyle says the only real solution is to replace the stocker completely with a full Öhlins rear shock or similar quality aftermarket unit. It is a big expense but one that riders never regret after doing it.
For rider comfort and increased ground clearance, rearsets are also common for the RC. Popular brands include Sato, Vortex, Gilles and Arata. The installation of new clip-ons can slightly raise the bar height and take some weight off the arms and wrists, which often helps a lot over the course of a day. For those riders trying to shave off as much weight as possible, aftermarket wheels are a great place to shed some unwanted pounds. BST and Dymag have carbon fiber wheels available if you have the bucks. For slightly less weight loss and a lower cost alternative, others opted for forged magnesium. Common brands we found include Marchesini, Marvic and Dymag.
Another upgrade is to replace the sprockets due to the tall gearing. As supplied from Honda, top speed can almost be reached in fifth gear because the bike will not pull redline in sixth. Changing the sprockets from the factory 16-tooth front and 40-tooth rear to a lower 15/41 setup will usually maintain the same top speed and increase drive out of corners too.
The stock braking system is more than adequate for most owners and even some track day enthusiasts, and most riders choose to leave it as is. But for those that can't leave it alone you may want to look at simply fitting HRC pads and call it a day because they are that good.
One of the strengths of the RC51 is that it is a well-built and trouble-free bike. There are no particular mechanical issues to watch out for and the mechanics we spoke to said that even during the 16,000-mile valve adjustments, they are often found to be in spec. Those that replaced their cams with aftermarket units in hopes of more power found that they were inferior to the OEM billet pieces and failed in about 20 percent of the bikes that used them.
We spoke to Garry Griffith of Southern Honda Powersports in Chattanooga, Tennessee, (the largest volume Honda dealer in the country) about the bike and he said it was a trouble free and rider friendly bike. Griffith is a former roadracer who actually won the 250cc national race at Mid Ohio in 1986 against several riders that would later become world champions. He has spent his entire life around Honda sportbikes, and said the RC51 is easy on tires and the narrow profile of the V-Twin made it a great platform for the AMA Superbike rules at the time. He also said that the relatively low rpms of the bike in race form allowed it to run longer between rebuilds than the typical inline four cylinders on the grid.
Owners of the RC51 are fiercely loyal to the bike and cling to them today even though they have been out of production for 3 years. If you overlooked this bike, it is not too late to scoop one up and enjoy one of the few purpose-built, somewhat readily available superbike platforms that ever sat on the floor of a Honda dealer.
