Ducati Monster Forum

So I opened up the stock exhausts on my '07 s2r 1k a little bit and the bike seems to be running a little leaner on closed throttle deceleration. It backfires worse than my dog regardless of engine temperature. Does anyone know from experience if I can richen it up a bit from turning in the air bleeds or will the closed loop cancel that out? I have read the thread(s) about closed loop mods but I would rather not throw more parts at the bike if I can find an answer w/ tuning.

I dont recommend playing with the airbleeds

if all you did is open the exhaust it should be fine, unless you notice it surging more than normal.

opening the airbox will cause problems with little choices on fixing them as of now

It is backfiring and surging. The surging goes away as it warms up ( which happens fairly quick in AZ) but is always there. As I recall it was there before, but less pronounced. I was pretty surprised by the whole thing. I was under the impression from reading other threads that air flow volume on these bikes was controlled by the airbox/filter and the udder. Anyhow I am not looking to "play" with anything, but I do want to explore solutions  to this problem I created that may already exist on the bike. Why would I have to alter the airbox? I thought these screws were on the throttle bodies as shown in the service manual (item #20 on page 48 of "2006 Monster S2R 1000 service manual"). Am I looking at the wrong screws"?

The surging and backfiring is from a lean condition, which the bike comes from the factory already lean to meet Euro 3 standards.

By adding only a slip on, it doesn't change the airflow that much, because as you stated the udder already allows enough backpressure.

Most people open the airbox as one of the common mods done, but by doing that opens the amount of airflow into the motor causing an even more lean condition. Lean isn't bad, however being overly lean will damage things.

The air screws will not change the lean/richness setting, only an aftermarket programmer or DP ECU for the Termi exhaust bypass the already lean condition.

I would talk to a dealer, or someone locally with more FI experience, mine is limited. 

Have you seen this thread:   http://ducatimonsterworldwide.org/index.php?topic=655.0 (http://ducatimonsterworldwide.org/index.php?topic=655.0)

Yes, I have read that thread. Maybe I should rephrase my question. I have cored out my stock mufflers. I have made no other changes to affect the air fuel ratio. Is there anything I can do that does not involve spending large sums of money to compensate for the increased leanness I have observed since making this modification? As I see it, from what I have read here and elsewhere, my choices are to either go back to all stock (which is still a little lean for me) -or- spend a pile of money on parts combinations none of which have consistent results (except the full DP setup).

Actually you can affect some change by opening/closing the airbleeds.  My dealer did it on my Tricolore after I complained about a small bit of backfiring through the airbox during low-speed around town riding.  It definitely lessened the occurrence, though hasn't eliminated it completely.  Whether this would be enough to offset the muffler "coring" you've done is unknown, but it wouldn't hurt to try.  If it's backfiring on decel then you know you're running too lean so richen it up.  If that doesn't cure it everything I read and everyone in-the-know I talk to seem to agree that the best fix overall is the DP ECU that comes with the Termi system.  Mine gets the full 50mm carbon system next week.  Quite expensive, but worth it.

 I can't believe I'm going to be the first person to mention this in the thread.

Most people have found satisfactory results by unplugging the O2 sensor. It's a zero cost mod so you don't have to worry about spending any cash.

 All you need to do is follow the wire from the O2 sensor up to the plug. It's right on the frame on the left side of the bike. Disconnect the battery and then unplug the O2 sensor. Leave the battery unplugged for about 1/2 hour. Reconnect the battery and ride, no more popping on decel. Have fun!  [moto]

 If you still find the bike is popping a little on decel, stop the bike and turn the key on and off about 6-7 times. on the last on/off cycle leave it on and let the gauges sweep like normal and then start it up. You're good to go!

Thanks for posting your procedure. I had pretty much ruled that one out in my head because it sounded like the results were inconsistent, or that it helped for a while but then the bikes would revert to the old lean symptoms. Have you heard/read different?

Once you have unplugged the O2 sensor, try this
http://cgi.ebay.com/ebaymotors/DYNO-BOOST-PERFORMANCE-CHIP-DUCATI-MONSTER-749-749R-999_W0QQcmdZViewItemQQcategoryZ34284QQihZ001QQitemZ110254530121QQrdZ1QQsspagenameZWDVW (http://cgi.ebay.com/ebaymotors/DYNO-BOOST-PERFORMANCE-CHIP-DUCATI-MONSTER-749-749R-999_W0QQcmdZViewItemQQcategoryZ34284QQihZ001QQitemZ110254530121QQrdZ1QQsspagenameZWDVW)
I want to give it a shot to see if it will richen up the mix a bit since I have the boomtubes and no O2 Sensor. Hell, it's less than $50 shipped. If it doesn't work, you aren't out much...

If unplugging the O2 sensor does work for you, then remove the sensor very shortly.  Running the O2 sensor w/o it being hooked up will kill the sensor and if you need it again....well, you would need to buy a new one at that point (big $$).

 Your finding you need to richen up the mixture with the O2 unplugged? Are you sure? I only ask because I am finding that my bike runs a little too rich with it unplugged. I'm running an exhaust setup similar to the Boom Tubes so it sounds a little strange to me. I'm actually thinking of adding a K&N air filter to see if I can lean it out a bit.

In answer to the air bleed question most of the bikes that have an o2 sensor the bleeds come through from the factory fully closed.

 Meaning that they are adjusted to the richest possible or the leanest?

Yeah, I'm pretty lean. When Mark made the set for me, he had to end up baffling the system to give it some back pressure. He said it sounded awesome, but was waaaay too lean...

Holy crap.  too good to be true?

When you have the air bleeds the screw is closing off the source for additional air to enter the system so closing it off will richen the system.
Except if you have an o2 sensor that senses the rich mixture and the leans out the mixture to compensate. [bang]

The mixture can be made richer using the trim function on the ECU

Ok, I had it richened up at the dealer using the trim right after I bought it to try and get rid of the surging. However now that I have the O2 unplugged, can they make it leaner to compensate because it's WAY too rich?

If it's too rich, take advantage of it and open up the airbox a bit more. Oh, when you got the bike dyno'd did you have them read the A/F mix?

Yes they can lean out the ecu as well with the o2 sensor removed. remember though that the o2 sensor only comes into play at low rpm and after you get above that rpm you are on a preprogramed (open loop) system. do not lean it out too much or your top end will be too lean.
It would be best to adjust the trim on the dyno to be sure you are not going to melt anything down and then set the lower rpm zone with a combination of air screw and trim.

Now we're cookin'. WTF is CO "trim" anyways? Is it just a fancy word for widening the injector pulses? The only trim I know is on planes and something else that has nothing to do with motorcycles.

 Here's the link to the post with the Dyno results:

 http://ducatimonsterworldwide.org/index.php?topic=2993.0

 In response to opening up the airbox a bit more I have to say I don't like the honking sound it makes when it's fully open. I ran it that way for a few days and it drove me nuts. It also didn't seem to help out that much.

 I am considering a K&N to see if that helps.

Ok, so just for laughs I started messing around with the adjustments on the air bleeds.

 I ended up turning the screws counter-clockwise about 2 full turns to add air and the bike seems to be running much smoother. It has more power everywhere and has no surging or popping on Decel.  [thumbsup]

 The only downside is that the idle is now a little higher. It's right around 1400 RPM's now but I can live with it to get the bike to run right.  [moto]

2 FULL turns? That's a huge adjustment!

 I know but my dealer had them almost fully closed from when he was trying to get it to run right with the O2 still connected. It made a difference but it still popped and surged so I removed the O2 and have been running it like that but it was way too rich. Now with the bleeds opened up it runs awsome, like it should have from the factory.

My not so good memory recalls some SR2 1000s running lean with the O₂ disconnected, some rich.  I guess there is no standard base map.  The air bleeds have diminishing effect with increased throttle, so, no backfire, problem solved. 

 Well yes, and no. I still think there is more power to be had. From my time riding with the O2 connected it felt like it had more power. I just couldn't deal with the surging/backfiring issues.  [bang]

If you are looking for more power with unplugging the o2 sensor then it is just not going to happen there is no magic genie that will give you more hp.
driveability it can do with some ecu/tune trickery. but if you are not getting more air and fuel into the motor you will not get more hp out.
also remember that an aftermarket ecu does more than just adjust fuel. it also adjusts ignition timing, red line and the fuel map (when the fuel is delivered as well as how much).

CO is carbon monoxide, you know the stuff that kills. It is the product of unburned combustion, so too much CO = too rich a mixture (or too lean but thats another story).
It is used as a giudeline reading for how well the engine is using its air fuel mixture.