Thank you so much for taking the time to share this with the community! Awesome explanation along with taking videos of the before and after. My '06 749 Dark had this problem, I was chasing all the wrong things, but finally able to fix it thanks to you! I know these are race bikes, but I can't believe these left the showroom with the throttle plates adjusted like that. Can't wait to get out on it and just enjoy the ride, without worrying or revving at stop lights to keep it running! Thanks again!
Update from last night- I have been having this issue as I have been rebuilding my 999. I followed the instruction of this video and it solved the stalling issue. I ending up setting the idle to about 1800(more or less) no more stalling. I also watched the fuel build up on the butterfly valve. Upon adjusting the idle screw in there is no more fuel pooling on the plate. Good eye, you saved me hours of troubleshooting
I was never able to solve this problem in two different official Ducati workshops and other experts. The problem I had was with the motorcycle turning off without warning when idling, usually at a traffic light. There were valves adjusted 4 times, new yuasa battery, gasoline filter, dna air filters, new stator anyway... lots of love and lots of money... thanks for sharing your experience, it all makes sense!
I used to work in Ducati dealership back in the day and found exactly the same thing. We cured it using the same method but then slowed the tick over on the bypass screws, reset the throttle potentiometer and reset the CO. Once we knew it was a fix we knew where to drill a 10 mm hole in the top of the airbox on other bikes so we could adjust the throttle stop screw without taking all of the airbox to bits. Finally sealing it with a sealing grommet. 749S's were particularly prone to this.
That really interesting to know. Did you ever see this is on any of ST4S models? I’m having the same stalling issues at lights and bouncing at very low speed which I believe is fuelling.
@markbarton6845 No, this was never an issue with any of the other models. Sounds a bit like a fuelling issue, low pump pressure perhaps due to lower voltage at tickover causing the pump/ filter to give a lower pressure. Have you tried changing the fuel filter? They have been known to split at at join an the metal ones.
Just for clarification. The pooling problem only happens on Ducati's that have shower head injectors I.e. where the injectors were above the throttle valves. Models like the ST4s had the injectors below the throttle valves, 2 injectors per cylinder on the ST4s if I remember correctly.
@@stevenrowley9481 ok thanks that sound like a great suggestion I get Ducati to have a look at it. One thing I would like some knowledge on if you have time is an on going clutch issue. I keep getting loss of pressure on the clutch. I’ve had the clutch and slave replace but it keeps happening. Any ideas would be welcome. To give you an idea…It seem ok in town but once I’ve done some country road and go back to using it their suddenly no pressure. I see no fluid leaking which is very strange.
Bloody hell. Freakin' excellent explanation. I have a 749 that has been to numerous mechanics at Ducati and independent. No one could figure out why. So it's been sitting for years now cuz it was too dangerous to ride. THANK YOU!!!!!
Very interesting. My 999 always suffered from the same problem. Also difficult starting. The immobiliser eventually packed up, so I replaced the ecu with one from a 1098, and copied the mapping from a 999 race bike. Problem went away to a large extent, but it still hunts a little at idle. Thanks for the explanation - very interesting.
Awesome video. I've had my 2002 998 (same motor at the 999) since 2007 and am amazed that I can still learn things about it. Too many people attribute these stalling issues to it being a Ducati, but I always believed it was how they were set up and tuned. You're the first to be able to explain this with evidence, so great job! By the way, I used to have a stalling issue with my bike and also couldn't start it without using the start lever. After a tune-up by someone who actually knew what they were doing, it idles cleanly and I never need to use that start lever either.
999s was my best bike. It was a dream to ride. She had full termignoni system and the performance cam pack, it was a missile. The Ohlins shocks and the brembo radial brakes, oh boy such a great control... I switched from a 2005 R1 and the Duc was like a bike from the future back then. I still miss my good old trile nine s.
I bought a 749 dark, and it stalls at traffic lights etc.. I dont mind it that much but it should be an easy fix then :D Thank you thank you thank you :D
Placing the injector above the butterfly valve also good for keeping the throttle body and the plate clean. Placing the injector below the plate can cause carbon buildup on and around the plate (similar to small petrol turbo direct injected car engines where the cam valves needs to be cleaned periodically which isn't an issue for non direct injected ones. tfsi vs t-jet for example.)
Interesting, I changed my ECU to DP for a Termi system and idle speed is too low, I over come that by increasing the rpm with the start lever on the left side, which in effect just opens the throttle a bit more, I don’t want to adjust it as I don’t have a dealer with all the kit like you have set up there and it runs very nice as it is.
Great explanation! Do you have any advice on setting up the bypass on the S4RS? (Same Engine as the 999 but injectors are spraying behind the throttle bodies) After a full rebuild and cleaning i have issues with stalling while pulling the clutch and closing the throttle. I also have the possibility to run JPDiag if this helps.
Hi, thanks :) Unfortunately we don't have too much specific experience with this exact issue on the S4RS. We did have an S4RS in a few years ago that was running poorly on idle and it did need the A/F mixture adjusted properly. We used our wide band dyno AFR sensors to fix it properly though, so you will need access to something similar to the same. That said it could be something else especially as it has been rebuilt but I would be checking the A/F mixture first.
Hey thanks for the reply. When you made this adjustment on the rear throttle body did it also adjust the front open as well since they are connected ? How many turns of that idle screw to open it more? Do you set the air bypass all the way closed or open 1/4 turn? @@RaceCenterAU
Hi there, I've been running my 2004 999s for years now with no understanding of why it cuts out. I have played around with the idle screw many times which does improve it. I like to keep my idle speed around 1300rpm as the bike overheats quickly with it any higher. My bike has many little things giving trouble these days which keeps me busy......... relays, wiring loom connectors, ecu , cold starting, stator voltage output too high. The list is long but I still like the machine. It's a pity you're not in NZ because I have many questions I would love answers to concerning all the gremlins. Great vid though. Cheers
Thanks! Sorry can't quite remember exactly how man turns it needed. Wasn't heaps, just get the idle up around 1,600 to 1,800 and that should do the job
Brill vid mate. I've been pullint my hair out for the best part of a year replacing every component on my 1098 for these stupid stalling issues. It can idle fine for a few mins and randomly drop off. One run i had a ridiculous ammount of backfire which was a first and plugs going from soaked to normal. Ive literally replacrd next to every component on my bike to no avail. It will idle around 1350-1450 quite steadily I had the trims and tbs balancdd by a specialist etc but it will still randomly die or cut out. Ive noticed quite abit of rev hang during idle revving. Doesnt ever shut off when its moving the bike but only on idling. Had me bricking it at traffic lights a few times. Really at a loss to what thr issue is. Looking at this video though perhaps the 1098 suffers from the same problem? Cant remember the exact injector layout if its the same as the 999. Any insight would help, alot of mechs local to me wont touch it and even the specialist couldn't resolve it.
I was thinking the same when I watched this video. This should affect any bike with shower injectors and opposite-opening butterflies. The 1098 does have shower injectors, just not sure about the butterflies, but it makes sense that it should if the point is to avoid creating turbulence as described in the video.
Hi PL - Shep Sorry for the late reply. We missed this one. Look I am not completely sure with the 1098 as we haven't done the same thing with one. Also we are not aware that it is a common problem with them as it is with the 999 and 749 models. So, my first gut instinct is something else is up, also this issue described in this video does not have the symptom of rev hang that you describe, so I am think it might be something else. But unsure tbh. Would kind of need the bike to diagnose it.
Do you close the front bleed screw as well. I made the adjustment to the rear and it worked perfectly. I think the front air bleed should.be closed also.simce the throttlebodies are linked
New guy question because I have the "stalling when going back on throttle after a stoplight/sign" problem: what do those by-pass screws do? I've just turned them in both clockwise and counter-clockwise direction to increase the idle speed and nothing seemed to change. From your video, it seems that I need to open the airbox and adjust the idle screw on the throttle bodies? (which is not in the Ducati service manual instructions, just the by-pass screws). TIA!
The by-pass screws change the air/fuel ratio at idle and very low throttle. You really shouldn't be adjusting them without some AFR sensors or the Ducati Diag tool or an equivalent. No what we did is not in the ducati service manual and that's why we did the video :)
I had a 2004 999 with a Termi pipe. It did the same thing. Would stall at the lights when i pulled in the clutch. I installed a Power Commander 3 on the bike and it never stalled again.
What he is describing the stalling and the mix change from lean to rich and miss fire and backfire sounds for me that the throttle position sensor is defect or wrong adjusted . This TPS is a simpel potentiometer. We drive mostly the in the first 30% of the range the TPS that stress change the resistance in this area and the ECU get wrong values . I think it was at IDLE I150mV and must go smooth to 450mV full throttle .
I'd probably be a little careful with that because once you do it, you can't undo it. It would only need to be a very little bit. And if you make it too big, you are also adding more air so that will affect the tune on idle as well and you'd need to adjust the AFR. Also doing that will increase the idle anyway because you are effectively opening the throttle plate anyway, just in a different way. But yeah sure the concept would work and we thought about drilling a tinny. Suggest if you go down that path do it in very small increments. But as you will increase the idle that way anyway, you might just be best increasing the idle as in the video,
@@MotoTingle Sorry buddy. The bike is no longer here so we can't do that. Also, it is not the most simple task, so we do recommend it be done by someone experienced with working on these bikes, and if you are going to do it properly you will need the diagnostic tool to adjust Air Fuel ratio. Sorry we couldn't be of more help
@@RaceCenterAU I appreciate the reply. I have a 999s and the diagnostic tool. Might give it a go. The bikes only just started stalling occasionally. Will do a video on it once time allows. Thanks for getting back to me
Hey dude I hope you got it fixed by now but if not, the screw your looking for is on the side of the throttle body it is an allen wrench type screw that pushed down on the black cable holder (for lack of a better word) you only need to rotate it like 2 or 3mm, very small adjustment to let that fuel go down. You can access it from the battery side of the bike, you can open the airbox and crack it open a 1/2 inch and you can access it.
Ducati 999s , Termignioni, factory ECU. The exhaust has very bad acidic smell, My friends in the car following me say the bike is not running right and smells bad. What could be the problem and also how to fix it?
@@RaceCenterAU Been always like that, around idle or when rpm is falling from high to low, pulling the clutch, stalls, or wants to stall, then backfires and keeps going. I have not raised the idle yet, per this video, but the mixture seems to be very off. How could someone adjust the air fuel ratio on these bikes? It got factory race ECU that came with the bike. I got this bike brand new from Ducati dealer.
@@desmomotodesmomoto2033 Ok. I think firstly you have the same issue that is described in the video and it should be fixed like we have described in the video. The you need the dealer or your mechanic to adjust the fuel ratio via the Ducati tool or equivalent. Then it would be best it dyno tuned but you would need to find someone that you trust knows what they are doing. Where are you located?
