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Discussion Starter · #1 ·
Wondering if anyone has an issue where engine RPM's hang a bit after closing the throttle? I've noted for a while now, though not systematically pinned it down to precise conditions, where I roll off the throttle but RPM's don't drop immediately, or they drop much slower than one would expect. First noticed when coming to a stop and pulling in the clutch and putting in Neutral and the RPM's would hang at 1.2 or 1.3K before dropping to 1.1K. From time to time would also note that engine braking was inconsistent, like maybe 5% of the time - meaning after rolling off throttle the engine braking would not be as hard because RPM's did not come down as quickly as expected. Did some riding today in enduro mode on a dirt road, downhill, where I'd close the throttle and the RPM's would not drop and there was no noticeable engine braking.

Is it just me?
 

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There is no idle adjsutment as such...(air bypass screws do something). Mine idles 1200 to 1300. What about everone else??
 

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at times when I pull up at lights or stop at an intersection my MTS 1200 does the same, but worse! It fast idles around 1700-1900 RPM for a few seconds before it finally drops down to the set 1100 RPM idle speed. My bike is yet to have its 600 mile service, plan is to have them resolve this during the 1st service.

It seems to be intermittent on my bike, maybe 1 in every 6 times I pull up at lights or stop it does it.

I know from my old days as a mechanic, cars had a deceleration valve which if adjusted incorrectly it caused the same problem. So I'm inclined to think its a vacuum to atmosphere pressure issue - the air bleed down screw
 

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People seem to play willy-nilly with the two air bleed screws. Count the turns from where factory set to fully closed....then work back out again from there. My dealer fiddled with them without bothering to remember where they were...so it's been hit and miss since then. Let's see what others come up with on this.
 

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Check the position of your hand and the grip when this happens. I'll bet you $10 you don't have the throttle closed. I have the same issue on this bike and have since day 1. I had them take a little free play out of the throttle, but the fact is the return spring is too softa and I have to conciously close it every time. That plus the longer throttle turn in most modes are what I think does it to me. This is the first bike I've ever had this issue with.
 

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There is an air leak somewhere or TB balance issue. Did you take off the emissions canister? If yes, check to be sure the hoses are sealed. Air blead screws might also do something about it. What bike do you have?
 

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I noticed this when I first bought my bike (used) but didn't pay much attention to it until I got my bike back from the local precinct (impounded, driving out of class) and it was hanging more. On colder days it hangs less. My gsxr came right back down almost instantly, all the time. My 749 hangs like yours. I just live with it.
 

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My '10 touring does it a bit as well. Started after it got it's only ecu update at the 600 mile service, and the tech mentioned that it would do this. It doesn't really hang up, just takes a second or two longer to return to it's normal idle when the throttle is released. I'm used to it now, and think nothing of it.
 

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Discussion Starter · #12 ·
Lots of folks seem to notice an RPM hang when throttle is closed and returning to idle - anyone ever notice an RPM hang when riding and you close the throttle? I've noticed a few times coming up to a turn and I use some engine braking to set the turn entrance speed that from a reduction in throttle the RPM's hang a bit and I don't get the engine brake expected, so I have to hit the brakes. I suppose it's possible that in such cases I'm not closing the throttle all the way, but I'm pretty sure that I am. Also, on yesterday's ride I was going downhill in first gear on gravel and I had the throttle completely closed and the RPM's were hanging up at 3K or so; where I should have been getting engine braking I was instead coasting (clutch was engaged).
 

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im feeling the same thing... feels like being 'pushed' into the corner when you really expected engine braking. starting to wonder if its dirt or grime or something gumming up the servo or throttle body linkages. i have a 'reasonable' amount of free play at the twist grip, so another theory is maby cables to the tps are sticking just a little, within the range of the free play...
 

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my feel is more the TB linkages though, as the bike in general feels a bit sluggish to respond to changes at the twist grip. theres kind of a lag between twisting the grip, and the response from the engine. just a seconds hesitation, then on she comes or mostly off she goes...
 

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Everyone who thinks it's in their fueling system, I challenge you do simply pull in the clutch and take your hand off the throttle entirely. See if it still hangs. My problem is 100 percent the throttle return and the hanging is being caused by me not getting the throttle closed all the way when I brake. I can avoid the hanging if I conciously 'over close' the throttle, but when I do a normal brake to a stop, the throttle return spring isn't strong enough to get the last bit of closure against the pressure of my hand.
 

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Discussion Starter · #16 ·
Everyone who thinks it's in their fueling system, I challenge you do simply pull in the clutch and take your hand off the throttle entirely. See if it still hangs. My problem is 100 percent the throttle return and the hanging is being caused by me not getting the throttle closed all the way when I brake. I can avoid the hanging if I conciously 'over close' the throttle, but when I do a normal brake to a stop, the throttle return spring isn't strong enough to get the last bit of closure against the pressure of my hand.
Good suggestion. The problem is that it is intermittent - I'd say 5% of the time - and by the time I notice it happening and decide to take my hand off the throttle I'll be too busy trying to grab brake to keep from blowing a turn, or it will start to drop anyway. Gonna see what I can do to test this method out, though.
 

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Good suggestion. The problem is that it is intermittent - I'd say 5% of the time - and by the time I notice it happening and decide to take my hand off the throttle I'll be too busy trying to grab brake to keep from blowing a turn, or it will start to drop anyway. Gonna see what I can do to test this method out, though.
I find myself on most of my bikes not closing the throttle all the way while braking. I have to consciously make myself unwind the throttle completely. I suggest those that find themselves in an uncomfortable situation, slip the clutch, that will definitely reduce the bike's drive. I also try not to chop the throttle under heavy cornering because it upsets the bike. Neutral throttle and a little brake make for a quicker entry and exit. If I ran at the corners on my Hyper and chopped the throttle and jumped on the brakes, at some point I would certainly be eating asphalt soufflé. Depending on the gravel road you are riding, try not to enter a turn too briskly unless you plan on dirt tracking through it. Momentum, looking ahead, sliding rearward on the seat and not death gripping the bars works best when riding on gravel, dirt or sand. I've ridden Baja several times and learned the faster you go and the farther you get back on the bike the more stable the bike becomes. Never chop the throttle on loose footing and never fixate on an object, look where you're headed.
 

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Good suggestion. The problem is that it is intermittent - I'd say 5% of the time - and by the time I notice it happening and decide to take my hand off the throttle I'll be too busy trying to grab brake to keep from blowing a turn, or it will start to drop anyway. Gonna see what I can do to test this method out, though.
Same here. It happens intermittently, because I'm not consistently getting a full close of the throttle when I brake on this bike. But every time it happens, as soon as I fully close the throttle it stops. Only bike I've ever had this problem on. I just compared the throttle return pressure between my Multi and my Tuono and it is night and day different.

I also think that some of it is the riding position, as I've never had a bike where I'm so upright and the bars are generally straight level with my elbows. It creates a different angle and less natural pressure in the direction of a throttle close.
 

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Fatduc Post Installation Tuning Method

thought you guys maybe interested in reading this from the FatDuc FAQ webpage...

A very small percentage of bikes will need an adjustment of the throttle body air bypass screws after installation. The richer mixture created by the O2 Manipulator can sometimes create a surging or sticking idle. Opening the air bypass screws will allow additional oxygen into the richer fuel mixture and stabilize the idle. Do not be alarmed if your idle suddenly sticks between 2,000 – 2,500 RPMs or hunts/surges after installation. A couple of small adjustments between the air bypass screws and O2 Manipulator can have your bike running like it never has before. Additional details are included with the supplied installation instructions.


What should I expect after installation?
Since the ECU uses an overall average from the O2 sensor, you will need to ride the bike for a few miles to allow for the ECU to adapt to the O2 Manipulator. You will not need any special tools or test equipment to confirm if the O2 Manipulator is working. The effects of the device are easily felt during normal operation.


What setting should be used on the O2 Manipulator’s variable trimmer?
Each bike will be slightly different due to any aftermarket modifications to the intake or exhaust system as well as the manufacturer’s tolerances of the various parts (i.e. fuel injectors, O2 sensor) used when the motorcycle was built. The overall goal is to use the leanest setting possible on the O2 Manipulator that reduces or eliminates the lean fueling problems. Too rich can create a “mushy” throttle and waste fuel, too lean will not eliminate lean fueling problems. It’s best to start somewhere in the middle and adjust as needed. You will want to make very small adjustments to the variable trimmer and then ride for a few miles to allow for the ECU to adapt to the new setting

What do I personally learn from the above, or what am I getting at you ask? Well, the way I see it, as a result of the Fatduc R&D and in particular the product refinement, they have learnt that RPM hanging is the result of the AFR being to rich. I've been racing & riding bikes since 8YO, I turn 51 this year and have never heard so much absolute garbage when people say I and others who are experiencing RPM hang dont know how to release a motor bikes throttle properly!

Giving this further thought, when you close any throttle on any engine, does the AFR become - for a short period, to lean or rich? This is a factory inherited ECU AFR deceleration Mapping problem!! Read my post earlier on in this thread. Ducati needs to resolve this, not us. A service bulletin is warrented here - flash upgrade of the ECU Map at next service interval. On the other hand....... have play with the idle AFR screw's, if that dont eradicate the RPM hang then buy a Fatduc. No I aint affiliated in any shape, form or fashion
 

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hmmm.. mine started after the tank was removed and replaced by the dealer... no mapping changes... im still hedging towards a mechanical thing...
 
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