| Author |
Message |
    
Spuds
| | Posted on Wednesday, October 06, 2010 - 12:25 pm: | 
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Hi.
Not looking for the solution here - just folks' descriptions of the infamous "3-4K flat spot" that a lot of people talk about on xb's.
I know what my bike is doing, I know what I've done to try to make it better, but there's still something not right. I've started to wonder: maybe it's the infamous flat spot.
So my request is to all you early model xb9 owners out there: does/did your bike have the flat spot? what does/did it do or feel like? When do/did you feel it? (accelerating? constant throttle, etc). I'm trying to figure out what I'm dealing with first...then I'll try to fix it.
Thanks VERY much, in advance |
Blake
| | Posted on Wednesday, October 06, 2010 - 01:03 pm: |
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Never heard of that flat spot for an XB9, only for XB12 with interactive exhaust.
Different exhaust tract designs offer different power-band characteristics. See the XB muffler dyno shootout results at American Sport Bike for information that will illustrate the issue very well.
Bottom line is that no one exhaust system is the be all end all in performance. Each has stronger and weaker points compared to others. You have to decide what type of powerband best suits you. |
Spuds
| | Posted on Wednesday, October 06, 2010 - 02:25 pm: |
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Oh. Only on 12's. Well, I guess then that that is still useful info....my 9r is doing something that it perhaps shouldn't be doing.
Sigh.
thanks for the response Blake!!
Rod |
Aptbldr
| | Posted on Thursday, October 07, 2010 - 07:58 am: |
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Spuds, have you done the "white wire mod"?
http://www.ukbeg.com/forum/viewtopic.php?f=17&t=11 &p=19&hilit=white+wire#p19 |
Spuds
| | Posted on Thursday, October 07, 2010 - 11:22 am: |
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the white wire mod.....no...never heard of it. thanks - might just try this... |
Jandj_davis
| | Posted on Friday, October 08, 2010 - 10:38 am: |
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My 9R has a HUGE flat spot between 3-4K RPM. I have a cut up airbox with the race kit, which is supposed to exaggerate the issue. I feel it when I am on the gas hard, sweeping the needle from 2K to 5K. There is an easy to feel lack of acceleration as the needle sweeps from 3-4K. The bike doesn't stop accelerating, it just doesn't go with a linear response.
Rolling on from 3.5K, it is hard to feel, but it is definitely there when traversing the RPM range from bottom to top.
I'm told that ECMSpy can be used to change the ignition timing and fueling in that area to clean it up a lot, but I haven't had any luck with that at all. I just ended up with a bike that wouldn't idle, but ran like hell from 3K to peak. |
Spuds
| | Posted on Friday, October 08, 2010 - 10:59 am: |
|
thanks for the responses so far....
On a similar post in the xbBoard, I was reminded that there is also a breather hose rerouting mod that I've always sorta knew about, but never paid much attention to.
Hitting an auto parts store this afternoon to pick up a few pieces....gonna try to do the mod this weekend. |
Rjlefevre
| | Posted on Monday, October 11, 2010 - 03:28 pm: |
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I had the same flat spot from 3k to 4.5k rpm on my 2005 XB9SX.
I was advised trying some fuel injector cleaner from the local auto part shop to make sure it wasn't just some stuff clogging the injector up. Weirdly enough, my bike now has a completely linear acceleration curve. |
Terrys1980
| | Posted on Monday, October 11, 2010 - 05:56 pm: |
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I seriously doubt a dirty injector will effect just a small spot in the RPM range. If your injectors are that dirty the bikes overall performance will suffer.
(Message edited by terrys1980 on October 11, 2010) |
Spuds
| | Posted on Tuesday, October 12, 2010 - 09:03 am: |
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The update so far:
http://www.badweatherbikers.com/buell/messages/327 77/598089.html?1286888397
Did a simplified breather hose re-route...still in "not getting hopes up" test mode...but so far, it seems to have made a positive difference.... |
Aptbldr
| | Posted on Tuesday, October 12, 2010 - 12:57 pm: |
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Breather reroute was "most bang" for a single mod with my XB12, (except when I'd screw-up re-mapping ECM and it wouldn't run at all). |
Spuds
| | Posted on Wednesday, October 13, 2010 - 11:10 am: |
|
Crap.
Spoke too soon.
The sputtering/hesitating is still there.
It idles at 1000, drops to half that for a second or so, picks itself back up, couple of seconds later it drops again, picks itself back up.... This irregularity is what I'm sure I'm feeling as I'm riding too....
Coming to stops, the engine's idle hangs at about 2000 for a bit, then drops to normal...
I dunno. I'm frustrated. |
Terrys1980
| | Posted on Wednesday, October 13, 2010 - 12:29 pm: |
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If your idle is hanging around 2k it is set too high. |
Aptbldr
| | Posted on Wednesday, October 13, 2010 - 02:55 pm: |
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Set idle rpm (for me re-set) after engine is at full temperature. Or, hanging idle may ensue. |
Fahren
| | Posted on Friday, November 12, 2010 - 08:04 pm: |
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Do the white wire mod, as recommended above. |
Rekrab
| | Posted on Sunday, April 17, 2011 - 11:04 pm: |
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XB12X / 08 Started at about 25k with the jumpy idle and 3/4 k skip and lag. Many dealers across the country either thought it was fine or messed with plug wires , exhaust , TpS reset , ECM , sent me on my way . I rode 20 thousand miles with this crap. Finally before the warranty was up I told my dealer I would pay for dyno if they didn't find an issue. The fix was a new throttle body and the bike goes like crazy again ! 55 thousand miles now and looking forward to more cross country miles. |
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The omnipresent "flat spot" with xb's