| Author | Message | ||
     Stevel |
I think it is likely that many of you have experienced this light throttle surging. This makes the bike very difficult and even unpleasant to ride in traffic. Many attribute this to a very lean fuel map and although the factory maps are lean, please be aware that the throttle body syncronization on this engine is very critical and even the slightest imbalance in airflow between the two throttle bodies will generate this symtom. I have just balanced my '08 with a flow meter and the symtom almost totally dissappears. This adjustment is painful, as the mechanism on the rear throttle body linkage is very coarse and perfect balance is hard to achieve, but well worthwhile when you get it right}. Steve | ||
| Xl1200r |
How did you go about doing this? | ||
| T_man |
Thanks for information and the insight! Please share how we can replicate this on our bikes. | ||
| 1_mike |
Though I haven't done TB balancing on my CR...I fully agree with the premise. I've done my own work in tuning all of my bikes and cars over the last 43 years. I've had many cars with multiple carburetors. I've used several methods to balance them over the years. The only bike that never required "REbalancing", was my 03 Yamaha R1. The TB's always checked very good thru 98,000 miles (along with the valve adjustment). I'll wait till my service at the end of the year to check them. Mike | ||
| Stevel |
If you folks want to do this, get access to a carb airflow gauge or a vacuum manometer. I far prefer the air flow gauge for both ease of use and accuracy. I have had mine for thirty years, but they were at one time plentiful and inexpensive. Remove all the airboxes and air filter. Then the base plate and rubber seal. Be gentle and don't tear the rubber seal. It just slides off the throttle bodies, but it is tight. You will also have to disconnect the breather hoses that feed through the plastic base plate. Unclip the wiring harness on the left rear. Pop off the Bosch sensor at the back and remove the base plate. You will note that the rear TB is boss and the drag link on the right side connects the front TB to the rear TB by a pivoting plate secured to a mating plate permanently attached to the rear TB butterfly shaft. These plates are secured together by a small phillips screw, which has a drop of enamel applied at the factory. The outer plate is slotted and to facilitate adjustment, the screw is loosened slightly. Using two fingers apply pressure to the butterfly in the front TB. Be careful here, a little movement makes a big difference. Start the engine and let it settle to an idle. Place the air flow gauge over the rear TB, center the ball in the glass vial by adjusting the tool's venturi. Place tool over the forward TB and the ball should also be centered in the vial. If the position of the ball in the vial is different between the TBs , adjust the forward TB to match the rear TB. Have patience, you will need it, but once done, the result is well worth the trouble. While you are there, remove the cable from the 'noid to the rear TB, it is easy. Steve | ||
| Stevel |
The tool I use can be seen on eBay item number 250217502410 for $25. It is made by Empi | ||
| Zac4mac |
I think that the "Easy way" is to just tie the throttle plates together. I have believed that most of the rideability issues reflect to an imbalance and a timing issue. An imbalance should show with a wideband analysis of F-R A/F. Instead of a physical mod, you could change the pulse-width of the injector signal and alter the timing to get optimum output. Whoever said they miss carbs, doesn't "get it". Z | ||
| Stevel |
Z Adjusting mixture by modifying the AFR won't change the fact that one cylinder is effectively dragging the other simply because it is seeing more throttle and air. Getting the fuel charge correct is important, but so is balancing the air they receive. In fact it is primary. "I think that the "Easy way" is to just tie the throttle plates together." They already are. It is that link that must be adjusted so the respective air flows in the two throttle bodies are equal. Try it...it's free... I think you will like the results. Steve | ||
| Dirty_john |
yes I miss carbs, learnt to balance carbs on twins and fours back in 1975 and have rebuilt and setup so many I have lost count. Great fun setting up the balance of accelerator Dell O'rtos on Ducatis be ear. | ||
| Slypiranna |
This threads methods is not complete and/or accurate. It is NOT advised to attempt adjustment on the front and real "sync" of the 11's t-bodies as you risk voiding/screwing up an assembly that is just shy of $1,000.00... ...but if YOU MUST, here is the correct procedure; 1. Remove T-body assembly from engine. 2. Clean and lubricate all pivot points. 3. Remove the clutch vac lines from the intake manifold and hookup the test gauge lines there. 4. Block off ONE side of the MAP sensor lines. 5. Lock the throttle 1:1 as is common procedure in Noid Elimination...Disconnect or remove the Noid while in there... 6. Block off BOTH sides of the internal IDLE AIR passages within the T-bodies. 7. Acquire shim stock to manually adjust (place under the idle stop screw) the idle speed...or have a helper work the throttle to keep the engine from dieing. 8. Start the engine, allow to warm up being careful not to rap the throttle...and if you do rap the throttle, DO NOT decel quickly or you risk sucking the test gauge's fluid into the engine! 9. Adjust the throttles' bias until the gauges equalize...and yes, by breaking that seal on that screw, your now on your own! LOL! 10. Slowly increase the rpm and return to idle speed to verify accuracy. 11. Shut down and perform manual TPS reset procedures...yes the TPS is on the forward throttle shaft but this is irrelevant if all is done correctly. DO NOT MANUALLY ADJUST THE TPS MOUNTING RELATIONSHIP! 12. Access DIAG mode and verify TPS is 2 and 100% respectively...clear any trouble codes that MIGHT pop up while doing this procedure...like an IDLE AIR fault. 13. Remove T-bodies and put all lines back to stock. REMOVE PLUGS FROM IDLE AIR PASSAGES! 14. Reassemble, TAKE ALL SLACK OUT OF THROTTLE CABLES, start up while in DIAG mode and verify TPS is not fluttering while @ idle...turn handlebars lock to lock... If it is fluttering, readjust cables and/or repeat manual TPS reset procedure. 15. Test ride and repeat the above if anything proves negative. ********IT IS HIGHLY IMPORTANT THAT YOU DO NOT TOUCH THE CLUTCH LEVER WITH THE VAC LINES DISCONNECTED!********* mm | ||
| Blake |
1. Remove T-body assembly from engine. .8. Start the engine... .13. Remove T-bodies and put all lines back to stock. 14. Reassemble Uh, yeah, the other guy's procedure was not complete. Seems to me that putting an airflow gauge on each TB inlet without ever having to remove the TBs is far superior a method than whatever it is you are trying to describe. | ||
| Slypiranna |
Blake, There are 6 ports that tie both cylinder's intake tracks together. Without properly blocking them, any adjustment is folly. (2) Small vac lines that unite @ the MAP sensor's inlet. (Located under the throttle body assembly. (2) Large vac lines that "T" together for the Vac Assisted Clutch. (Located under the throttle body assembly. (2) Large passages within the throttle body assembly that port directly to the IAC. One cannot accurately and/or should not, adjust anything without truly divorcing these flow paths. Page 4-18 in the 2009 1125 Service Manual shows a pretty good picture. Hope this helps and sorry for any confusion. I really would hate to see an owner ruin his 11 based upon inaccurate information. | ||
| Blake |
Like trying to run the engine with the throttle bodies removed? Having the TBs connected via various vacuum lines doesn't render the air flow method inaccurate. Each TB should still be flowing the same amount of air. Sensor lines don't flow air. To be more accurate, you might want two air flow gauges instead of one so you can measure the two simultaneously. Your instructions make no sense. | ||
| Rainman |
Hmm, maybe I'll keep my Blast. All I have to worry about is that $10 boot. | ||
| Slypiranna |
You got me on one Blake! Thanks! Addition/Correction... 7a. Reinstall the t-bodies! LOL! Each TB flowing the same amount and/or sync'd is what I am referring to. It is assumed that anyone that is qualified to mess with this subject would be using individual sync gauges to adjust the front to rear cylinders intake "balance". ALL sensor lines/passages (described herein) on the 1125's throttle bodies DO FLOW/SHARE air between both cylinders when there is an imbalance between them. Happy Tuning! | ||
| Stevel |
Please note that I identified two methods. Using the an air flow meter and using a vacuum gauge. Please also note that I chose the air flow meter. The next folly is that vacuum lines flow air. If they do, it's called a leak. Fix the leak. If the vacuum port method is so good, why is it necessary to readjust on a brand NEW bike? Could it be because the factory uses the vacuum port method? The air flow method is easier, more accurate, faster, more safe and by far superior. Now, the suggestion of using two air flow gauges is reasonable at first glance, but in practice does not work because the air flow gauges will not be exactly the same. We are measuring relative flow difference and a single gauge is more accurate because it eliminates an unnecessary variable. Steve | ||
| Slypiranna |
As I originally posted...non of "this" is recommended. Rotax adjusts these units with far more precision than ANYONE playing on the outside. That should be a given... Variables? That's why multi cylinder sync gauges, such as these, have been around for so long for those that understand what to do with them.  | ||
| Slypiranna |
It's internet "advise" or recommendations like "this" that find a lot of bad results in the end... ...I question just how many 1125s Buell has already warrantied due to internet experts being applied by outsiders? I've heard of too many since this bike was released. Something to think about, I would hope. mm | ||
| Redscuell |
"I think it is likely that many of you have experienced this light throttle surging. This makes the bike very difficult and even unpleasant to ride in traffic. " Actually, I've commented many times just how much I HAVE experienced this; mine's an 09 with the 12Z map (it was worse with the 11Z map delivered with the bike) and no cat. Seems to me I was told here that I was just imagining the problem; which was simply a self-serving comment by one of the faithful. I solved it by changing the fuel maps. The 12Z map was measured to show that fueling in the 2000 - 5500 rpm range was in the 14-15:1 range (centred on stoich) at 10% throttle; and in the 15-16:1 range at 50% throttle. AMCN magazine, and my dyno tuner, recommend more like 13:1 ratios as being "the ideal mixture of fuel to air in a bike engine" (AMCN). Changing the map over to this range (now in the 11-13:1 range below 4000 rpm) was simple but not easy; but the jumpy throttle is gone. Your way, which you say works, would have been much simpler and cheaper and faster, I daresay! Just getting together all the hardware and software took some time, much less learning to use it and then implementing the changes. Good on ya! | ||
| Ezblast |
I wouldn't go below 12, the 11s can be a bit too rich - which can be bad. 12 to 13.5 is a good range to aim in. EZ (Message edited by ezblast on September 22, 2009) | ||
| Redscuell |
"I wouldn't go below 12," No argument there -- and yet it was the stock -11Z map that was delivering 10s above 5750 rpm at 10% throttle, 11s at 50%! The 12Z map fixed that beautifully (all around 13 above that same rev point) so I appreciate that fix; but as outlined above, the jumpy remained at lower revs so I made it go away. (Message edited by redscuell on September 23, 2009) | ||
| Stevel |
"AMCN magazine, and my dyno tuner, recommend more like 13:1 ratios as being "the ideal mixture of fuel to air in a bike engine" (AMCN). Changing the map over to this range (now in the 11-13:1 range below 4000 rpm) was simple but not easy; but the jumpy throttle is gone." Red, I have been hot rodding motors for 50 yrs and what I learned is that "rich" hides a lot of faults, but rich is not better. There is a very old and true saying "Lean is mean" , but the best tune for power pushes against the edge of the safety envelope. The safety envelope is different for every engine, but the edge is fatter for air cooled motors than water cooled motors. The 1125 will make best power between 13.1 and 13.7. Any richer and you will lose power. The logic in the Buell ECM will force 15 to 16:1 AFR in cruise mode and even if you change the fuel map in this range, the ECM will simply change the AFV to compensate. You should try to achieve stoich (14.7:1) in the map for this mode, but you should be using a wideband O2 sensor and a data logger. Otherwise, you will have no idea what really is happening. Please also remember that dyno time is expensive, but easy to get close. It is however, not the total answer. You don't ride a dyno. Also, many dyno tuners use a single sensor in the exhaust, this is not very accurate. You have a fuel map for each cylinder and to really know, you need to place the wideband in both header pipes and tune as if you were tuning two single cylinder motors. I am curious about your software setup that you use to modify the ECM. Can you elaborate? I am setting myself up to use ECMspy, but I am waiting on a cable. I also have not made up my mind on which wideband sensor to use, but I am leaning toward the new Bosch planar sensors. If anyone else has done this, I'm all ears. Steve | ||
| Blake |
The surging happens on the air-cooled bikes too, only one throttle body there. | ||
| Stevel |
Blake, You are correct, it can. It is more common in some engines than others. I am assuming you are referring to Sportster motors. In those engines, it is caused by three factors, cam overlap, non-symetrical firing order (exhaust reversion) and a very short intake runner. It can be tuned out by opening the inlet valve later, closing the exhaust valve earlier, spreading the valve centers or increasing the intake runner length. Unfortunately, all of those things will reduce available power, so a compromise must be reached creating acceptable drivability with acceptable power level. Not mentioned yet is raising the engine idle speed, which will mask the reversion somewhat. Please note that the very short stroke of the 11 forces the significantly higher idle speed. This is necessary to create adequate inlet air velocity in the inlet tract, which stops the gas reversion between the exhaust and inlet tract during valve overlap. All of those factors contribute to the 11's inability to make usable power below 2000 rpm. In comparison the sportster motor can pull tree stumps just above 1000 rpm. Now, you know why. The actual cause of the observed surge is inlet charge contamination by exhaust gases. This contamination causes the flame propagation chain to be intermittently broken at ignition time resulting in uneven cylinder pressure during the power stroke. Steve | ||
| Daggar |
Thanks for making me feel dumb, Steve.  | ||
| Blake |
No, I was talking about Buell engines. And I wasn't talking about idle, but cruising speed, around 3,000 rpm. No reversion there I don't think. I doubt it has anything to do with reversion. Non of the carbureted bikes had the issue, only the fuel injected ones. And then the surging in those has been remedied by remapping the EFI, so I can't see the validity in your explanation. | ||
| Slypiranna |
Factory 11's are simply JUST lean...PER PPM EMISSION/EPA REQUIREMENTS...within the CL Enabled zones. This thread's content (solve?) has nothing to do with mechanical design, cam timing, ect.,ect.,ect...let alone intake sync. Idle and Cruise RPM's are the areas most relevant to the EPA as you cannot spend much legal time in Open Loop/Warmup, transients/WOT. If tuned richer and a slight modification to timing (off road/racing)...there wouldn't be a need for all this as its already been proven. I must also add that after riding all the flashes and 11 models to date... BMC/ROTAX has done an EXCELLENT job of making the latest (stock) versions/flashes as good or better than competing brands while still adhering to EPA limits. The (stock) 09 R I recently rode was almost as good as a perfected race tune in cruise mode...and it wasn't even broken in yet! LOL! Hats off Buell! mm...  Continue with  | ||
| Fresnobuell |
Buell has learned a quick lesson with the fueling and subsequent ECM flashes. I agree, kudos to BMC. | ||
| Dirty_john |
Does anybody know the reference code for the latest flash for the United Kingdom 09 models please? | ||
| Stevel |
Blake, The Harley engine that Buell uses is from the Sportster. Yes, a too lean condition can also cause poor flame propagation in all engines, because the space becomes to large for the fire to spread from one fuel droplet to its neighbor, hence the erratic burn. Steve |
