Surging problem - Honda RC51 Forum : RC51 Motorcycle Forums
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post #1 of 15 (permalink) Old 05-06-2010, 08:18 AM Thread Starter
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Surging problem. Help!

Haven't had alot of saddle time on my RC so still learning to ride the bike. Maybe it's just me, but the bike refuses to run smoothly and surges badly at a steady throttle between 3000 and 3500 rpm. Above that it smooths out and runs strong. Bike came with Jardine RT-1 cans. Tailpipes are black but not sooty, so proably running rich. No Power Commander (nor do I know if fueling was ever remapped for the Jardines). Adjusted throttle cable free-play and throttle response is crisp. Starts easy and idles normally at 1300 rpm. Love the bike but the surging makes riding in city traffic a PITA. On the open road she runs awesome. Can a good Honda dealer run a diagnostic and/or remap the fueling (assuming that's the problem)? Throttle bodies out of sync? Injectors dirty? Bad fuel? Never riden another RC so have no comparison, but can't believe this is normal. Opinions? Thanks.

Doug

Last edited by oldgeezer; 05-06-2010 at 12:15 PM.
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post #2 of 15 (permalink) Old 05-06-2010, 02:23 PM
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Can you better describe the surging behavior?

I know my '02 does not like to putt in traffic below 3500 RPM.
The combination of large throttle bodies with barely cracked butterflies combined with on/off fuel injection can get into a lurching behavior.
I usually clutch it then smoothly reengage to stop that.
Once the throttles are open a bit more or the revs get up to 4000, no problem.

If it was a horse, I'd say it was chomping at the bits.
It just wants to be turned loose to run.
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post #3 of 15 (permalink) Old 05-06-2010, 03:28 PM Thread Starter
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Originally Posted by SubSailor View Post
Can you better describe the surging behavior?

I know my '02 does not like to putt in traffic below 3500 RPM.
The combination of large throttle bodies with barely cracked butterflies combined with on/off fuel injection can get into a lurching behavior.
I usually clutch it then smoothly reengage to stop that.
Once the throttles are open a bit more or the revs get up to 4000, no problem.

If it was a horse, I'd say it was chomping at the bits.
It just wants to be turned loose to run.
Hmmmm, no real need to describe the surging behavior any further as I think you just described the exact same symptoms I'm currently experiencing. What you said makes perfect sense - the big gulping throttle bodies mixed with trying to modulate small throttle openings creates a lurching sensation. And yes, I'm clutching it too, just to smooth out things untill I can build a few revs. By 3500 things are barely borderline and by 4k everything is smooth and all is well in the world. "Chomping at the bit" describes the behavior perfectly. This is my first V-twn so the learning curve is a distictly different one from my previous horses (2 VFR's, Triumph Sprint ST, and the silky smooth CBR1100XX). Must be the nature of the beast - thanks for easing my mental suffering.

Doug

Last edited by oldgeezer; 05-06-2010 at 04:39 PM.
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post #4 of 15 (permalink) Old 05-06-2010, 10:32 PM
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Change your gearing. Mine was like that till I changed it 15/42 seemed to make city riding better.
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post #5 of 15 (permalink) Old 05-07-2010, 06:51 AM Thread Starter
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Originally Posted by RJ7 View Post
Change your gearing. Mine was like that till I changed it 15/42 seemed to make city riding better.
One thing I forgot to mention is that the previous owner had put a 44 tooth rear sprocket on the bike. 44 seems awfully low gearing but I'm assuming he left the front sprocket stock which gives a 16/44 ratio. Don't know how that equates to the 15/42 most RC owners recommend. My bike pulls strong out of the corners and runs great on the open road, but it seems to be reving a little high at interstate speeds. I also think my speedometer is reading wildely optimistic, maybe 12 to 15% high. Gonna check my readings against a GPS this weekend. May have to spring for one of those SpeedoHealers.
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post #6 of 15 (permalink) Old 05-07-2010, 01:42 PM
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Originally Posted by oldgeezer View Post
One thing I forgot to mention is that the previous owner had put a 44 tooth rear sprocket on the bike. 44 seems awfully low gearing but I'm assuming he left the front sprocket stock which gives a 16/44 ratio. Don't know how that equates to the 15/42 most RC owners recommend. My bike pulls strong out of the corners and runs great on the open road, but it seems to be reving a little high at interstate speeds. I also think my speedometer is reading wildely optimistic, maybe 12 to 15% high. Gonna check my readings against a GPS this weekend. May have to spring for one of those SpeedoHealers.
It sounds like the gearing is still very close to the 15/42, so no need to make a change there. As for the lurching, it seems to be common on this, and a few other larg liter bike's. My Hayabusa does the same thing, those not quite as rough as my RC. Crusing at low speeds (under 35), in any gear other than 1st, and both my RC and Busa lurch. I feel it mostly when I am going through a school zone (which are 20mph).
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post #7 of 15 (permalink) Old 05-07-2010, 09:09 PM
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Feel your pain oldgeezer, but thats not a city bike. I don't think that can be dialed out. Any rpm over 4k should work. The standard advice about gearing set up does help though. Get a fuel mapping device installed anyway. You will have a better response.
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post #8 of 15 (permalink) Old 05-07-2010, 10:08 PM
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Just picked up an '04 RC, and have been riding it for a couple of weeks now. I have the exact same performance - seems to be a bit choppy around 3k rpms. I find myself doing just what subsailor does - when needed, I'll clutch in and reengage or even change gears depending. I read up a lot on these bikes before buying mine, so I was expecting some choppiness. Sure enough, it takes some getting used to, but once you get some speed up, it's all worth it! My bike is completely stock, and I'd like to keep it that way, so it's something I'll have to get used to!
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post #9 of 15 (permalink) Old 05-10-2010, 08:25 AM Thread Starter
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Originally Posted by mattr1 View Post
Just picked up an '04 RC, and have been riding it for a couple of weeks now. I have the exact same performance - seems to be a bit choppy around 3k rpms. I find myself doing just what subsailor does - when needed, I'll clutch in and reengage or even change gears depending. I read up a lot on these bikes before buying mine, so I was expecting some choppiness. Sure enough, it takes some getting used to, but once you get some speed up, it's all worth it! My bike is completely stock, and I'd like to keep it that way, so it's something I'll have to get used to!
I've only ridden mine about 5 times now, so I'm still learning the bike. Very different from any of my previous bikes, plus it's my first V-twin. Was able to get in a 200+ mile ride Saturday morning, and little by little I'm developing a feel for the bike. And as you said, out on the open road, she's sweet. I've just about learned how to ride it at slower speeds - clutch it if necessary, but about the only guarantee for eliminating the lurching is to maintain a steady throttle around 4000 rpm. It's rideable down to about 3500, but it's much smoother if you can keep it above that. At anything below 3500 and down to 3000, it's almost impossible to maintain smoothness without clutching it.
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post #10 of 15 (permalink) Old 05-26-2010, 11:20 PM
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Hi, I've owned my '04 for the last 253 miles and it's got stock 16/40 gearing and lurches while riding in town. I've found that if I can hold the throttle at a point where the bike is making power to move I'm fine. If I'm coasting, though, and trying to crack the throttle enough to keep from using the clutch it'll start to lurch until I either A) clutch it or B) accelerate.

It's still very early in my ownership to decide on a gearing change, but I haven't even used 6th gear yet on the interstate. Hell, I barely use 4th around town! But I did my first mileage check on fuel last week and I got 43.5 MPG with it, and I'd HATE to lose that (I use the bike to commute).
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