| Author | Message | ||
     Gio |
hi every body, i have an xb12s 2003, but i have some problems....considering the big twin why my bike don't have "motor break"? - when i close the gas the rpm go down very slow!!! I tried also another bike with pro race kit and i note the same problem, instead of an S1 (carburator) when you close the gas the rpm fall down. I know that is a different kind of engine, but i can not understand why this ECM does not work. is it normal? (as said my dealer) - he has mapped the ECM but the situation is the same. Have I to change with a power commander or i can solve the problem in another way? sorry for my terrible english - i speak in italian better  thank you in advance for your help gio | ||
| Captainplanet |
idle may be set too high. | ||
| Lance12r |
I agree with Capt. set your idle to 1050. I had mine at the upper limit 1150 and it settled slowly. | ||
| Yeahcmon |
Two Words.....Fuel Injection | ||
| Skully |
On the XB9, Buell intentionally programmed the fuel injection to drop RPMs slowly to reduce the effects of engine braking. It works only when you close the throttle. In other words, if you let off the throttle in 5th, subsequent down shifts to lower gears won't experience this. Keith | ||
| Wyckedflesh |
Its called "Flywheel Effect"... You have a HEAVY flywheel that is spinning at a high rate of speed (say 5000rpm) so then you have the laws of physics..."an object in motion stays in motion until acted upon by an outside source." In otherwords since there is no actual brake on the flywheel it takes it awhile for its mass to spin down from the drag of the compression, drivetrain etc etc etc. Unlike a repliracer IL4 which has a very lightweight flywheel, its mass is much lower and so looses its momentum much quicker from the same influences. | ||
| Hootowl |
The XB ECM keeps the gas on a little to reduce chassis pitching during abrupt decreases in throttle angle. It shouldn't make it slow to come down to idle speed. I also agree with the captain. Your idle is probably set too high. 100-150 RPM can be significant. If I set my X1 idle (no fancy ECM here) to 1200 RPM it drops slowly back to idle after being revved. 1050 RPM, it drops nicely. | ||
| Hootowl |
...Although you may want to check for an intake leak. | ||
| Skully |
What I am referring to is not "Flywheel Effect" as I have ridden pre-XB Buells and they do not do this. Buell may have done this to reduce chassis pitching, but engine braking will not cause the chassis to pitch like a good, hard pull on that front brake lever. Nope, I think it was done to reduce the chance of skidding the rear wheel with an abrupt down shift. I have a race prepped Honda CBR 600 F3 that I race in the CMRA. One careless down shift coming into Turn 7 at Oak Hill Raceway is enough to remind me every time. Keith | ||
| Gio |
thank you everybody, I'll check the idle... but i think it'is right. If i change the ECM, with another (power commander - for example) can i control the engine break better? gio | ||
| Slowby |
if the idle is high on any buell injection it will go down slow. fuel or tube frame, but they start easier with a 1050 - 1100 idle | ||
| Trenchtractor |
These XB's seem to have a problem with this... My bike has had my mechanic pulling his hair out for over a month now... It all seems DDFI related. Slow settle to idle was only one of the problems. It has not been idle setting related on my bike. Also, when on the cooler side of operating temp, it settles to idle fine. When warm it settles very slow. The Race ECM makes things worse... Anyone who wants to here the full story and is ready to hear me unload, send me a MSG with your e-mail. PS... Info from my dealer was sent from my dealer (to Buell) a week ago, digital technician readings and stuff. We still haven't heard back yet... Like I said, anyone want me to unload on the full story... | ||
| Henrik |
This may not at all relate, but on the carbed bikes, a slow return to idle is one of the signs of an intake leak  Just something to consider. Henrik | ||
| Hootowl |
Gio, The power commanders do not replace the ECM, they just modify the pulse width of the signal sent to the injectors by the ECM. It's an add-on. | ||
| Gio |
.... as you can see my technical know how is very looooow - is there a repair manual of xb anywhere? - i shoul have come back at school (also for english)  gio | ||
| Darthane |
The Buell Service Manual is what you're looking for, Gio - though I don't know if they make them in Italian! If you can find one, it is well worth the money. | ||
| Freyke |
I had the same prob with mine when the idle was set to 1100... Knocled it back to 1000 and wala! no problem... | ||
| Gio |
I checked the idle, it's around 1000/1100 rpm, I tried to decreas it turnig the screw behind the fork (near the air flow "mouth"  but also at 950/1000 rpm this engine don't want to fall. I hate this!!! gio | ||
| Hootowl |
You may want to check for an intake leak then. | ||
| Draoidh |
My bike and every XB I have seen so far is the same way. I believe this to be by design just like others here have stated. I do not think there is much you can do to change it. --D | ||
| Skully |
Has the TPS been reset (correctly)?  Keith | ||
| Gio |
I hope that TPS has been reseted correctly by my dealer when i had the first check at 1600 km. (now 2500 km) i read that taking away the control for the gas pollution and also leaving the "butterfly" open in the exaust it could be better. do you know something about it? gio | ||
| M1combat |
Anyone mind if I ask why it's a problem? My XB drops RPMs a little slower than my CB750 (carb'd) but I've never had it actually cause any trouble. Maybe yours is just dropping them VERY slowly though? There was an article on a website not too long ago that says they took a bunch of bikes out (R1, R6, XB12 and a few others) and the 12 had the least amount of engine braking out of all (except for a 2-stroke as I recall). | ||
| Buellkowski |
I'm with Wycked on this one. Torque comes from stroke AND mass. Gio, think of the slow rpm decrease as a necessary physical balance to the massive amounts of torque you enjoy with the rpm INcrease.  | ||
| Buckinfubba |
The tps and Idle adjustment like the others have said Brian lil drummer boy | ||
| Spyder12s |
all well and good but when you are stoped at a light and you bike is still at 1500 and SlOwLey coming down that seems to me to be an issue | ||
| Gio |
regarding the mass... really i don't understand why an S1 (1200 cc) has a great engine braking, when you close the throttle the arrow of the rpm fall down at zero. I had a suzuki dr big 750 single cylinder, i can assure you that the engine braking was terrifing. i know that these 2 bike are carb, but regarding the mass i think that they are not accountable to my problem. gio | ||
| Captainplanet |
Gio, Keep adjusting the idle lower until either the problem goes away or the bike will not idle any longer. If the problem goes away, but the bike idles lower than 1000rpm, then you may need a tps reset. The other thing about the xb, is that after you initally set the idle, the bike can be slow to settle back to idle until after you put a few miles on the bike, and then it will just sort itself out. I think some of the people referring to mass, (no offense guys) may not have experienced the particular problem you are having on an xb. It is very obvious that the bike is not operating correctly when it hangs at a high idle as you pull to a stop. | ||
| Buellkowski |
Gio, listen to the mechanics, not me. I didn't mean to confuse you.  (my reach exceeds my grasp...) edited by Buellkowski on April 30, 2004 | ||
| Trenchtractor |
Yeah, but Wycked, if it's flywheel effect due to mass, explain why it does it worse when the bike is hot?? Explain why it drops fine until it gets to a point the just hangs there, seemingly forever?? Explain why it does it at different revs depending on temp... When my bike is hot (operating temp), it is so bad some gear changes are impossible to match revs 'cos the bike sets RPM to wherever the hell it pleases... Don't bother making anymore excuses, guys. This is a fault. Your bike and mine shouldn't exhibit these symptoms... See your mechanic. Mine reckons my bike is bloody horrible. And he works in the shop where I bought it. You guys keep talking about idle settings... Like if the bike surges at constant speeds, adjust idle up but if is won't settle to idle, drop the idle setting... What about if your bike does both?? Mine does, and no amount of adjusting the idle has fixed either problem. Brad (Cringes and don's flame proof suit) edited by trenchtractor on May 01, 2004 | ||
| Slowby |
did you watch the temp sensor reading's rise? smoothly? always getting hotter? that is plastic in the middle of the sensor and ive seen vibration before on at least one of these bikes; i know it  also watch te tp readings as you cut the throttle open w/ the bike not running.spikes are bad. | ||
| Xbduck |
Umm, just a thought but could the throttle cable be bound or bent in some way to cause this to happen. My thought is that the throttle may not be coming back to a true at rest point, with no load. | ||
| Trenchtractor |
Dude, it's a four stroke... Push/pull cable set up... Even if it was binding up, you can force it closed somewhat... Besides I suggested that to the mechanic and he said he'd checked it, several times. Bear in mind my bike has spent most of the last 2 months with my mechanic. Good job it's under warrantee, then, hey? Temp sensor worked fine except for the spike. It did have a constant, steady rise. I didn't expect replacing it to fix my temp related woes, but it did. These things are plain weird. | ||
| Bykergeek |
The EFI is programmed to supply fuell during closed throttle rpm spindown to counteract torque braking effects. Couple that with a massy flywheel and you get what you have seen. | ||
| Boulderbiker |
Just a thought so that everyone stops talking in relatives, individuals who are having this problem, why don't you rev to a certain rpm, when the bike is cold, then time how long it takes to drop down to 1500, then do it again when the bike is warmed up. That way we can all at least speak in absolute terms about the symptoms we're each experiencing. My bike is what I would call "slower" to return to idle than an inline four, but as many have stated already, Buell designed the FI to supply some gas on closed throttle so that engine braking isn't unsettlingly strong like in the article that M1 referenced. Like I said at the beginning though, for those who are having "problems" give us some times instead of relative terms so that we're all at least on the same page. | ||
| Fookinbueller |
Mine does this same issue only when hot, park it for a half an hour and it's back to normal... WTF? I hate it because, I'm one of those guys that loves a fair amount of engine breaking and loves it to be predictable... When I come into a slow turn and expect it to be there and it's not it makes it difficult to be smooth, causing you to quickly grab some brake to scrub off speed that for the last hour the engine braking was taking care of, that to me is a much greater issue than the extremely slight chance that I might, out of nowhere mind you, forget that the bike I've been riding, is prone to engine braking and skid the rear because, I ham fisted the clutch and down shift entering a turn... Which would really only happen, if the engine braking aspects of your bike were unpredictable, in which case it wouldn't be, if the friggin thing wouldn't act erratic with temp changes. If that makes sense... xb12s, Buell race can, ecm and filter... |
