[DownAnda]

Can anyone tell me why the bike should run lean with an aftermarket exhaust, or it will run more lean with that special one exhaust?
For my understanding the reason for a lean run is a sport airlifter like K&N. The orig. Lambda can not regulate the fuel flow so the bike will run lean. But the exhaust does not effect the air-fuel mixture.
Is there something i don't know or realize?
Thx for any advise!

 

[tonyjuliano]

Can anyone tell me why the bike should run lean with an aftermarket exhaust, or it will run more lean with that special one exhaust?
For my understanding the reason for a lean run is a sport airlifter like K&N. The orig. Lambda can not regulate the fuel flow so the bike will run lean. But the exhaust does not effect the air-fuel mixture.
Is there something i don't know or realize?
Thx for any advise!

Theoretically, any pressure in the exhaust system outside the cylinder will affect the amount of waste gas left in the cylinder. A more free flowing exhaust system will encourage those gasses to move along the pipe more quickly, lowering the pressure so next time the exhaust valve opens, there is less to block the exhaust gasses from leaving the cylinder. Less free flowing exhaust = a more restrictive exit along the pipe = more gasses at exhaust valve hindering exit of new gas from cylinder.

The lambda probes cannot react quickly enough to rapid change in rpm's so fueling is only altered by feedback from them during relatively long stretches of consistent throttle. Any other condition, and it's "fuel map only".

A simple slip-on should not affect the system very much, but most bikes are overly-lean from the manufacturer as it is (to get them through emissions testing).

 

[DJKham]

... which really begs the question that I've been wondering since I got the Scrambler: do the aftermarket exhaust on this bike affect the fueling negatively in any noticeable way? Even if it's slight, I would love to hear testimonials from people who have done aftermarket slip-ons (termi not included) without a remap.

 

[tonyjuliano]

"Testimonials" in this regard have historically been incredibly inaccurate.

You will hear all manner of opinion, from those who surely posses fully calibrated "butt-dyno's".

The only way to be sure is to see actual dyno run numbers. I wouldn't accept anything else.

It's way too easy for people to "feel" the placebo effect, and report erroneous info as a result. While I'm sure a decent slip on could yield a couple of hp (certainly no more), the likely fact is that there isn't a whole lot more to be had out of this motor without spending serious money - which just isn't worth it, IMO.

In the end, it's a 75 hp bike -'never going to be much more - and personally that's one of the reasons I bought it in the first place.




Sent from my iPad using Tapatalk

 

[scramblinman]

Power aside, the question unanswered is if keeping the bike lean for a long period of time (the life of it post slip-on install) will cause any long-term issues?

 

[tonyjuliano]

Severe lean conditions can lead to some pretty nice holes in the tops of your pistons, and valve damage.

But again, just a slip on - without any other changes on the intake side - really shouldn't cause this big a problem.

A simple reading of the spark plugs would tell you all you needed to know about this - post install.


Sent from my iPad using Tapatalk

 

[thewanderingmikeyb]

I have put on a SC Project exhaust and just going on fuel consumption it has leaned it out about 5%… I am going to try a Booster Plug, which claims to richen up the mixture, hopefully it should put it close back to original mixture but with the extra noise of the aftermarket exhaust… It takes up to 18 days for the Booster plug to get delivered to Australia though, so it's a wait and see at this point until I get it!
DUCATI Scrambler BoosterPlug

 

[silverluxe]

It's probably a question for a general Ducati forum where people have a lot more miles and experience doing this to Monsters. From what I have seen it's hard to tell because not that many owners keep bikes long enough. The sort of people that mod the bike with a pipe but no tuning will usually end up buying a new bike before the old one ever died from the exhaust. Also people who put on a pipe but no tuning for it are less picky than I am, so their opinion would probably differ from mine in terms of what their thoughts are. I've been digging how my bike is quieter than all of my friends but it's quicker than their bikes.

There's a lot of people out there running all kinds of fuel injected bikes with slip on mufflers who have put on a lot of miles that way. The question is do you want to be the person that kills the engine at 75k miles or 200k miles? Either way it's a lot of life out of a bike even if it's diminished by running a bit lean. In my opinion there's room for improvement to the factory map that could theoretically add life to the engine.

 

[DownAnda]

Thank you for you quick answer, that was the point i was missing.

 

[silverluxe]

Also, a lot of people that leave the bike alone and go to the dealer religiously for every service are riding less aggressively.

So I have to say "your mileage may vary" because there are so many variable aspects of owning, operating, and modifying the bikes.

I think the good news is that putting most of these slip-on mufflers on the bike isn't going to hurt it enough to kill the bike. Fuel injection + four stroke = fairly safe.

I have spent a couple of decades in the vintage scooter scene where people hop up Vespa and Lambretta scooters and I have definitely seen people soft seize, hard seize, and put holes in their pistons while we're at a rally riding. The funny part is that most people do this because they're trying to get to the bleeding edge of lean so their scooter will go 2mph faster than it did when it was in the safe range.

Also, people doing this 'tuning' usually aren't completely in understanding of how to do it right. ie: they MIGHT change the pilot jets out, but most of them just increase the main jet size and almost none of them change out the atomizer tube because they haven't sat down and taught themselves carburetor theory. I've been on rides where someone holed a piston in 3rd gear at easy crusing speed because his midrange carb setting was too lean. Meanwhile if he would have been riding wide open throttle at 80mph he would have been fine all day long.

At scooter rallies, people are constantly locking up their rear tires when the pistons seize in the cylinders. I don't know why other than that humans are inherently flawed into not being able to just leave things alone, set at the factory settings (which never seize the engine.)

Long story short is that I haven't seen these sort of problems in modern motorcycles, but I see it all the time with vintage 2 stroke stuff and -sometimes- with vintage four stroke stuff. I've seen someone hole the pistons of a Yamaha XS650 but that was the only 4 stroke I've ever seen destroyed with lean settings. I'm not saying it's not possible, but I think we're all safe (enough) purchasing these name brand aftermarket pipes for the Ducati Scrambler.

 

[tonyjuliano]

I have put on a SC Project exhaust and just going on fuel consumption it has leaned it out about 5%… I am going to try a Booster Plug, which claims to richen up the mixture, hopefully it should put it close back to original mixture but with the extra noise of the aftermarket exhaust… It takes up to 18 days for the Booster plug to get delivered to Australia though, so it's a wait and see at this point until I get it!
DUCATI Scrambler BoosterPlug

I would love to know how you determined that the bike is running 5% leaner based on "fuel consumption"...

 

[tonyjuliano]

Oh, and I am sure you are are convinced that the "booster plug" is going to have a totally positive influence on the bike, but for the rest of you out there...

This kind of stuff has been around the automotive world for years. It is a resistor that splices into the intake air temperature sensor circuit (either in series to make it a higher resistance or it just bypasses the sensor all together and gives a fixed reading) to make the ECU think the intake air is colder than it really is. Unless your feedback (o2 sensor) system has been disabled it wont make enough difference to matter. The ECU will detect any extra fuel (lack of oxygen actually) in the exhaust and compensate by leaning the mixture. More advanced ECU's will learn over time that the IAT sensor is reading too cold and permanently compensate it warmer, rendering the resistor 100% useless instead of the normal 99% useless.

 

[Ottodesmo]

I am a bit old skool so I checked the plugs before and after running my Virex slip-on for the first time. See the pictures below. I think the first picture shows a good to almost too rich mixture (black deposits, good color central electrode), and the after picture is definitely leaner but not too white so probably not too lean. Having said that, this does noot say anything about the fueling on constant level, acceleration etc, just a general indication. I think it could do with some remapping as I think that it could run better still. It responds well but when decelerating you can hear some rumbling sometimes.


The Ducati Dealer here in Amsterdam told me that apparently there have been made changes to the mapping over the first six months; their demo bike, which I've ridden too, was quite snappy on the throttle, wehereas my Icon is much bettter (and was produced a couple of months later). He also said that apparently the US bikes are running different maps which are leaner than EU spec bikes.


Otto