The Honda RC51 came in two different "versions"... the original SP1 (2000-2001) and the improved SP2 (2002+). Below is a brief description of some of the differences between the two versions... with the SP2 seeing a lot of improvements.

[Taken from a discussion thread on RC51 Forums]:

Whatever the multimillion-dollar factory riders want, it seems they get. And if any of those changes happen to benefit street riders, well fine — but it's almost an accident. So it is for 2002: A multitude of tweaks have arrived to make the 2002 RC51 more competitive on the track, but the trickle-down effect is that the bike is now much improved for puck-wearing plebes.

For 2002, Honda chose to tweak the engine a bit, put the entire bike on a part-by-part diet and significantly revise the suspension, chassis and swingarm. Down in the engine room, the throttle bodies have been supersized from 54mm to 62mm, and the two injectors feeding each combustion chamber now sport 12 laser-drilled jets, rather than the four little garden hoses of the previous bike, for a finer spray. The injection and ignition mapping were tweaked, also, resulting in throttle response that's as smooth and creamy as a nougat filling. (Don't tell Nicky; he's got a sweet tooth.) The new motor feels same-same in terms of power output; Honda claims a 2hp increase for 128hp at the crank — but the low-rev snatchiness is nowhere to be found.

The engine is warmed over, but as Honda's Doug Toland said at the intro, "All of the 'magic' of this bike is in the chassis." The new Pro Frame looks similar to last year's and has the same amount of rigidity, but weighs 260g less and is more linear in its absorption of stress thanks in part to the new stamped engine hangers (previous units were cast). Also new is a steering-damper boss up by the steering head, but on the stock geometry you'd be hard pressed to make this bike shake its head on the street or track.

Even though the steering-head angle has been reduced one degree to 23.5° — the steepest of any Honda — the RC51 feels planted at all speeds, even at 130mph through Willow Springs' infamous Turn Eight. There you sit, tucked behind the splendid new windscreen that's 1.2" taller than last year's, sensing no instability from either end of the bike. Of course, the new swingarm (890g lighter) is 16mm longer and aids the stabilization effort.

Right above that sexy new swingarm is a revised shock (115g lighter). It's been repositioned to allow room for aftermarket exhaust systems, but also had its linkage ratio tweaked (4% softer on the bottom, 5% softer on top), even though spring rates are the same. Nine percent more compression damping has been added along with 11% more rebound. Up front similar tweaks have been applied. The fork (145g lighter) is now 9% softer on compression, up 16% on rebound, with the same spring rate. Fork travel has also been increased from 4.7" to 5.1". These changes make the bike feel plush and controllable — a far cry from the wooden feel of the previous bike. The suspension is simply awesome now, soaking up midcorner ripples yet never getting out of line or doing anything untoward.

Steering effort is drastically reduced on the new bike. The RC51 is no 954 in terms of flickability, but the new bike turns in with an ease and precision that's head and shoulders above the old bike. Pick your line, shove the bar and you're there. The previous unit's brakes were fine, but the new four-piston jobbies are even better. The old brakes were extremely progressive — once activated you only had to move your finger a smidge to stop the bike. The new brakes are totally linear and require more lever travel, providing better feel, easier modulation and more feedback.

Speaking of feedback, the RC51 comes wrapped in a new flavor of Dunlop rubber named D208. The 208s are quite soft for a street tire, which allows them to heat up quickly and throw down GP-like grip. Feedback from both the front and rear was excellent, with excellent straight-line stability and precise steering at high and low speeds.

Our only complaint (and we think some folks at American Honda's marketing department will back us up on this) is that the bike looks exactly the same as last year's. Europe gets a bitchin' white/grey, but we get the same paint job as before. If you go out and buy the "new" model with all the killer updates, you want people to know, but it's literally impossible to tell the two bikes apart from a distance.

Paint job aside, the changes made to the RC51 for 2002 signify a Paul Bunyan-size step forward. Oh, did we mention the 2002 RC51 is the same price as last year's?