| Author | Message | ||
     Spuds |
Hi. I also posted this in the knowedgevault, so apologies to the site admin's in advance. 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? I've been reading/seeing folks talk about the "flat spot", and thought, ya...so it's a flat spot. I know what that means....an area where 'power is not as strong'... Ok. yup. So before I just conclude that it is "the flat spot" my request 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 | ||
| F1fletch |
My Friend has an XB9 with a Jardine and I have ridden it previously and did not notice a flat spot. The surging and other issues have plagued him though. On my XB12 it all came down to the exhaust and map. A good exhaust is a must (Drummer), follow that up with a good map and you will see success. My .02 | ||
| Spuds |
hi, Blake responded to my KV post...reminded me that it's the 12's that seem to have this "flat spot", not the 9's. But you guessed my bike dilemna...a bit of surging, sputtering, feeling lazy. not all the time, but enough that it's bugging me. we've installed new plugs, wires, coil, O2 sensor, cam position sensor. I ensure that there's a good coat of di-electric grease on the bottoms of the plug wire boots (it does not like running in the rain). We also discovered that the spark plug boots had been damaged, so they weren't making good contact with the plugs, so changed the wires again. I've had a regularly cleaned/oiled K&N air filter, a 12 airbox, the Race ECM, and a Spec Ops pipe on it since 11,000 kms. At about 45000 kms, it started acting up, intermittently. 65000 kms on it now.... maybe it's time to have someone "put a different/good" map in the ECM? I won't say it's running on one cylinder (it did...last summer and this spring...I know what that feels like!!). thought we'd fixed it. It just feels like it stumbles a bit on constant throttle, and it hates the first few minutes of running cold. I start it, let it idle for a minute, then hold steady throttle at, say 2500 rpm, just to help it "warm up", and despite me holding the throttle steady, the revs just drop back to almost nothing on their own. crawling out of the residential neighborhood requires feathering the clutch...it wants to stall. once warmed up, it just seems to be the general, subtle stumbling, roughness. I love this bike. I can't see me ever not having it. I just wish it ran like it used to. I know....it's getting older, like us all. Sigh. | ||
| Iamarchangel |
Wow, that's certainly not typical of mine. '03 9R with about 55k km. I would suggest the holding at 2500rpm is a bad habit and probably interferes more than it helps. Don't know about the drop in rpms after. I haven't really noticed any flat spot but I try to keep it revving high. I don't go more than third gear in the city. It doesn't like to cruise at about 4100. Somebody said there is an ECM change after a few moments there. That seems to fit the description. One thing I've thought of is that our Ontario laws seems to be at odd with the ECM settings. I have wondered if putting the 12 pulleys and belt, thus changing revs to miles settings, would help that. | ||
| Fast1075 |
Two possibilities...first is check for air leaks in the intake tract...sometimes they leak worse when the engine is not up to temp. Second thing....TPS....I know of two bikes that were cured of that miserable stumbling by replacing the tps after all else failed...one of them was mine...it is pretty easy on an early model. If the stumble is directly proportional to throttle position regardless of other factors, it may well be the TPS. | ||
| Blake |
What Fast said! | ||
| Blake |
And check for dirty injectors too. | ||
| Terrys1980 |
The flat spot can be tuned out but it takes quite a bit of work in the timing maps as well as the fuel maps. | ||
| Nillaice |
it's the 12 primary you'd want to change to. the +04 belt and pulleys are all the same ratio/tooth count | ||
| Spuds |
ya...I don't typically hold the revs at 2500 while it's warming up...it was just something I tried once in a while ...to see...what it would do. thanks for the other suggestions...we did also check for air intake leaks, and for dirty fuel injectors...sorry...forgot to mention that. I'm curious about the TPS suggestion - we've done a handful of tps resets, but are you suggesting to actually replace the TPS with a new one? hmmm... | ||
| Loud_and_low |
My experience with the "flat spot": I don't notice it on the street because for me, monster acceleration isn't needed there. But on the track for trackdays, I had an issue with the flat spot. Coming out of corners where the exit has a slight uphill, if I were exiting with the rpm's too low, ( too high of a gear), there was a lag in the powerband until about 4500rpms, where the acceleration was then acceptable. While this was a real problem, the solution I found was this: carry more corner speed so the rpm's were higher at exit. SO I found more about the possible speed I could carry through that corner, which eventually led me to going through the corner at 5500 instead of 3500. Exiting then allowed me to not get dropped by the liter bikes on the exit. That was delayed until 2/3 down the straight, but kept me close enough to catch up with late braking and more corner speed...Anyway, long story short, The flat spot was there, but instead of changing my bike, I learned how to make it work for me. Of all of the bikes I've owned in my life, the Buell has done the most for my skills. | ||
| Blake |
I don't care what bike or what state of tune it is in, if you exit a turn in too low of a gear you are f^%#€d in a race. That's not a flat spot issue. It's a bad choice of gear issue. Is that what you were trying to say? | ||
| Iamarchangel |
It's what I was trying to say. This bike has a power band like a two stroke: there's the narrow power bit and a bigger cruising bit and a big blaarg bit. Blaarg means change gears. Works for me. I was hitting an S today at 140 in a 90, and noticed a black and white entering the S at the other end. Finish the corner, back off, sit up straight and smile. I love this bike. | ||
| Starter |
yeah flat spot = not enough revs. Seems to be similar to reports of pinging. High load, low revs, high gear, lotsa throttle a we are surprised they bog and ping????? | ||
| 1_mike |
Had this "flat spot" problem with my 05, 12S in the 3000rpm area. Not any problem with the engine, or TPS, or leaking intake...."just" mapping (like I'd bet most are). Fed it some more fuel... (and a little timing), all problems gone..! Smooth from idle up, in a fast throttle or a slow throttle movement, will cruise smoothly at most any rpm now, including 3000. Mike | ||
| Glitch |
Catch can | ||
| Speedfreaks101 |
If you have a tuner/diagnostic program you can watch the tps % as you slowly open it. It should be smooth and should not jump any % points. By the rpm fluctuating it sounds more like a vacuum leak to me. A easy way to check this is to take the air box cover & airbox off. Remove air filter. Remove the intake boot. Crank the bike, let it idle, and use your hand to restrict the air coming into the throttle body, as if you are making the OK sign on top of the throttle body . If the RPM increases then you have a vacuum leak. | ||
| Spuds |
catch can....breather hose reroute....right. seen that talked about many times here....never paid much attention to it. hitting an auto parts store this afternoon. | ||
| Fast1075 |
One more thing to look for...where the TPS plugs into the wiring loom, there is a mount tab that goes into the injector rail...mine had come loose and the wiring on the harness side rubbed completely thru the insulation creating an intermittent short... | ||
| Spuds |
Well, rerouted the breather hoses out to just behind the rider's left footpeg on Friday evening. Easy and painless to do. Went for a short ride Friday evening - just into/around town, seemed to run better. Took it out for a proper thrashing this morning on a favourite route, and I noticed a difference. It was still a little grumpy as I left the house, but once it warmed up, it was better. Gone was the slight hesitating/stuttering under constant throttle. I think the mod was worthwhile and will know more over the next couple of days as it returns to utilitarian commuter duties...you know...gotta be on better behavior in town/traffic etc. After considering advice form all here, my mod so far consists of a T under the airbox base plate to join the two breather hoses (both shortened a bit for better fit), a short piece of hose forming a U to "block off" the two holes in the base plate where the breather hoses originally vented, and a single piece of hose off the T running out to the rider's left footpeg. I did not run another hose out to any breather filter, nor have I installed a catch can (yet?). I guess if the seepage gets too bad, a catch can will be necessary, and I guess that then sorta necessitates a separate hose with a breather filter. Thanks again to everyone here who offered advice/info. Rod | ||
| Loud_and_low |
Cool. I think it's time I do my re-route. I have put it off more or less for lack of a suitable(to me), catch can. My airbox doesn't show much evidence of oil or blow by, so I think I'll try without a catch can for now. See how it goes. Thanks for the motivation. | ||
| 1324 |
Spuds, It sounds like you do not have a line open to atmosphere (filter or open). If not, I recommend you add this now. The crankcase needs to vent. Personally, I run one 3/8" line to a filter for each cylinder and then tee into one catch can/line to maintain adequate flow (read: factory). Creating a breathing restriction will eventually lead to blown seals... | ||
| Gunut75 |
1324, yeah he does. I had to read it twice, as he combined the routing, and blocking stock holes in the same sentence. I ran mine down by my left footpeg, and it puked a lot of $h1t on the rear wheel. I switched it to a catch can. It's amazing how much condensation gets puked out. I couldn't imagine it going into my airbox. You will be fine running it to the footpeg, just be ready to clean the wheel every now and then. Sometimes I forget to empty the catch can, and it makes a mess as well. (Message edited by gunut75 on October 12, 2010) | ||
| Spuds |
Too much turkey on the weekend!! Could have been a little more clear in my description. The two hoses from the engine are now joined at a T, with a single hose coming off the T going downward to the footpeg area, where it ends open to the atmosphere. | ||
| Spuds |
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. | ||
| 1324 |
If I were in your shoes: 1. Reset TPS. 2. Adjust idle to 950-1000 RPM. Too high will cause hanging idle when coming to a stop. 3. Check static timing - to be thorough. Probably not the cause, but good to verify. 4. Check for intake seal leaks. 5. If problem persists, swap for original ECM or EEPROM. 6. If problem persists, diagnose bad TPS. On a side note, how is your battery? Age? Good charge? Batteries and bad grounds can be elusive... | ||
| Spuds |
k....will try those. thanks. I had already told myself that I would throw the stock ECM back in and try that for a while. Battery - is 2-3 years old. Have not had it on a meter or anything, but it cranks the bike strongly on start up. | ||
| Fast1075 |
Come and go problems are hard to nail down...my bike hates bad air (hot, humid) and loves good air (cool, dry)...it seems it has trouble adjusting for the differences...lately it has been coolish and it has run very well, with very little in the way of acting up...on hot damp days it is too rich right off idle (race ECM)..the stock ECM is a nightmare of snatchy throttle and herky jerky.....If I ride it like I stole it (like it was designed to be run) it is a complete hoot to ride... | ||
| F1fletch |
Spuds After resetting you TPS, make sure and adjust idle AFTER the nike is nice and hot, then set idle to 1050. I experienced a great deal of what you are seeing after changing my pipe and map (wouldn't idle, hung up at high idle after getting hot etc). The ECM has to learn especially in idle enrichment mode after any changes. Let it sputter and spit and die, then restart. Resist the urge to keep it running with the throttle. Once the bike adjusts to new settings via the ECM it will idle fine unless you really do have a problem. It sounds like you are covering your bases, be patient and you will get it :-) | ||
| Livers |
Don't give up yet, Spuds. Lots of good info above. More ideas: Stick your finger in the pipe and run it around. What does it look like? What do the plugs look like? Have you swapped relays? Checked your grounds? Done a thorough visual inspection of the entire wiring harness? |
