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Discussion Starter · #1 ·
what are the differences between the sp1 and sp2? from what i read it sounds like an improvement was made to soften the driveline lash/bucking/surging. Can anyone confirm this?

were there any other real changes?
 

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This little article details changes in the SP2 RC51 which came out in 2002. I've wanted this bike since it's intro in '00, I'm glad I waited, the SP2's seems to have been tweaked just a tad nicer............................. John

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 '02 RC51 more competitive on the track, but the trickle-down effect is that the bike is now much improved for puck-wearing plebes.

For '02, 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 two-horsepower increase for 128 hp 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 260 grams 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 degrees--the steepest of any Honda--the RC51 feels planted at all speeds, even at 130 mph through Willow Springs' infamous Turn Eight. There you sit, tucked behind the splendid new windscreen that's 1.2 inches taller than last year's, sensing no instability from either end of the bike. Of course, the new swingarm (890 grams lighter) is 16mm longer and aids the stabilization effort.


Right above that sexy new swingarm is a revised shock (115 grams lighter). It's been repositioned to allow room for aftermarket exhaust systems, but also had its linkage ratio tweaked (4 percent softer on the bottom, 5 percent softer on top), even though spring rates are the same. Nine percent more compression damping has been added along with 11 percent more rebound. Up front similar tweaks have been applied. The fork (145 grams lighter) is now 9 percent softer on compression, up 16 percent on rebound, with the same spring rate. Fork travel has also been increased from 4.7 to 5.1 inches. 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 '02 signify a Paul Bunyan-size step forward. Oh, did we mention the '02 RC51 is the same price as last year?
From an thread posted last year.
 

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Basically to answer your question specifically they just changed the injectors. The 02-06 injectors have more holes in them allowing better fuel atomization and therefor improving the low rpm jerking.
 

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Basically to answer your question specifically they just changed the injectors. The 02-06 injectors have more holes in them allowing better fuel atomization and therefor improving the low rpm jerking.
Actually, the larger throttle body and better tune play a bigger part. "More holes" just makes combustion more efficient and less prone to misfire and knock.
 

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Actually, the larger throttle body and better tune play a bigger part. "More holes" just makes combustion more efficient and less prone to misfire and knock.
I'm gonna go ahead and completely disagree with you there and say thats false. If you look at any of the threads on other sites where people have done the sp2 throttle body swap to an sp1 they say there was no change as far as the jerking was concerned.

I'll say it again. If the jerking is a problem then change the gearing and it will go away.
 

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I'm gonna go ahead and completely disagree with you there and say thats false. If you look at any of the threads on other sites where people have done the sp2 throttle body swap to an sp1 they say there was no change as far as the jerking was concerned.
Have them swap JUST the injectors and see how much of a difference THAT makes. ;) It's a combination of that and the new timing/fuel maps. No one of those changes will make too much of a difference by itself... With a background in turbo cars, I'd bet that it's 90% tuning....
 

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I agree with the tuning part but our buddy finepooch up there that started this thread doesn't believe the hype when it comes to a power commander & tuning. Which is why I mentioned the gear swap.
 

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Discussion Starter · #9 ·
i believe the pc and tuning is good but not a must. if the sp2 is tuned from the factory for smoother throttle responce that's even better.
 

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Throttle response yes but it wasn't hondas intentions to tune because of the low rpm jerking. They didn't go into 2002 saying the complaints about the jerking are getting bad so lets install a whole new fuel system and ecu to deal with it. Their intentions were to improve throttle response and horse power. If you've ridden an sp1 & 2 they both feel almost identical at very low speed and low throttle. The only way to eliminate the jerking is to change your gearing and tune it out.
 

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test on track...see which is better in speed
 

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Unless your bike is a WSBK spec RC51, I doubt you'll ever tell the difference.
All the improvements that went into the SP2 were to cope with race conditions that 99.9% of us will never apply.
 

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Discussion Starter · #15 ·
my only complaint on my sp1 is the low speed/low throttle driveline lash. is that the correct term? i'm trying to refer to the bucking/surging/lunging.

and i was under the impression that the sp2's fueling was tweaked for smoothness. is it a bit better or not better at all?
 

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Same as mine..but a fren of mine did changed his SP1 to a SP2 trottle boddies, SP2 airbox, PC3 & dyno..result @ he said it felt much better & no more surged when on/off trottle..
 

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my only complaint on my sp1 is the low speed/low throttle driveline lash. is that the correct term? i'm trying to refer to the bucking/surging/lunging.

and i was under the impression that the sp2's fueling was tweaked for smoothness. is it a bit better or not better at all?
Yes it is smoother off the line! It also might be due to differences in the clutches too.
 

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Unless your bike is a WSBK spec RC51, I doubt you'll ever tell the difference.
All the improvements that went into the SP2 were to cope with race conditions that 99.9% of us will never apply.
Truer words have never been spoken.

my only complaint on my sp1 is the low speed/low throttle driveline lash. is that the correct term? i'm trying to refer to the bucking/surging/lunging.

and i was under the impression that the sp2's fueling was tweaked for smoothness. is it a bit better or not better at all?
Pooch you have been told 50 times now how to fix it so suck it up and do whats been suggested and stop complaining about it.

PC3 & dyno..
That will cure it for sure.
 
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