[Cesare57]

I've been vacillating for months about getting one, mostly because I'm torn over whether smoothing out the throttle down low would be worth the drop in mileage.

However, after looking at my plugs recently and noticing how light they are - only 1 has the typical light brown color you associate with a healthy mixture while the rest are nearly white - I'm wondering would the Fat Duc be "healthier" for the motor by compensating for the overly lean settings of the stock ECU?

 

[DUCeditor]

after looking at my plugs recently and noticing how light they are - only 1 has the typical light brown color you associate with a healthy mixture while the rest are nearly white - I'm wondering would the Fat Duc be "healthier" for the motor by compensating for the overly lean settings of the stock ECU?

Theoretically a slightly rich mixture has several advantages. The first is that it runs cooler. Not primarily the type of cooler that will show on the temp gauge (although it does), but cooler in critical areas like around the exhaust valve.

Too, a rich mixture masks cylinder imbalance and the stresses this imposes on the crankshaft and (even) the cam drive.

But whether these differences would make a measurable difference in the motor's longevity remain as open question.

Regarding your expressed concern for reduced mileage do remember that the Fatduc is not and "on" "off" device. You can choose how much enrichment - with its benefits and costs - you'd like. I have even adjusted mine mid-trip when I was about to enter a long stretch of delightful back road without a filling station.

-don

 

[Cesare57]

Thanks Don, that's good to know.

 

[Libertarian]

It also takes about 10 seconds to put on or off, so it'd be easy to do mid-trip if you needed to.

 

[giogolf]

Maybe I did not set my Fat DUC to rich when I had it but I did not notice a decrease in mileage.

I did notice a bit of throttle lag or slow response time when giving gas sometimes. That's why i got rid of the Fat Duc, I was not crazy about the lose of feel or thrust I would get when grabbing a handful of throttle to take off.

However, I do regret getting rid of it now that I have installed my Emgo (AKA Cheap Bastard pipes), the Fat Duc really did smooth out the engine down low. I notice now without exhaust restriction how poorly the bike runs in the low RPM's

My bike could really use a Throttle Sync and richer mixture now. The stock pipes masked these issues for me.

FYI: I am not complaining about my Emgo's the bike is more responsive and peppy with them and I would recommend them to everyone who is running stock pipes as long as the user is willing to fabricate baffles to hush them up a bit.

Anyway back on topic, I would buy one try it out if you do not like it you can always sell it in the classifieds for $10 less than you paid (consider it a rental fee):think:

 

[Biz]

I have mine set about 1/8 turn richer than original setting, and it runs so well I haven't been tempted to richen it up any further. Yes the mileage dropped, so you will have to decide for yourself if it is worth it to get smoother running, more power/torque, better throttle response, cooler running, no stalling or surging, and a/f mixture set to what the bike wants rather than what the EPA wants, is worth the 5-10 miles per TANK fuel mileage hit. (54-55 mpg now vs. 57 mpg stock) To me it's a no brainer. YMMV.

Dave

 

[MajorSoftie]

On the one hand, yes, a slightly richer mixture is probably better for the engine; mostly because it runs a little cooler.

On the other hand, too rich a mixture is not. It allows less lubrication to remain on the cylinder walls for ring lubrication and results in more deposit build-up. It also can destroy and possibly clog your catalytic converter (if you have one).

Also, you can't necessarily make such assumptions about mixture from your plug color. Heat range has a large impact on plug color, and modern fuels do not leave as much color on the plug as what we were burning 20 years ago - even more so if there is alcohol in your fuel.

 

[Cesare57]

Guys - thanks for your valuable imput. That's what I love about this place!

Biz - I believe you're the first person I've heard mention a power\torque gain from the FD, and given the other benefits you list weighed against the negligable mileage loss you've experienced, it really does seem like a no-brainer. I'm sold!

Worse case scenario, if I decide for some reason I don't like it I'm sure I could re-sell it for a small loss as giogolf pointed out - maybe to him to replace the one he sold!

 

[tsmgguy]

I've had the Fatduc on the GT since they became available. I've experienced all of the good things that you've heard about with NO reduction in gas milage. I'd never consider removing it without some really good reason. IMHO, it's the best and cheapest single mod that you can do!

 

[DUCeditor]

Biz - I believe you're the first person I've heard mention a power\torque gain from the FD

I doubt there is one that would be measurable on a dyno. But what matters to a street rider is how it feels and in my experience the increased smoothness of the motor with the Fatduc installed encourages more enthusiastic throttle twisting. To the rider that translates as both a more powerful and more responsive motor.

Whether one sees a change in miles per gallon probably is effected in part by how the Fatduc influences the rider's riding style. Obviously the MPG will go down if the rider gets more enthusiastic with the throttle.

But there is another possibility as well: A Fatduc equipped machine is so buttery smooth down low that a rider may stay in this range much of the time. Smooth or no at low RPM, the DS engine was designed for mid-range efficiency. Using a lower RPM band might thus lower MPG.

It bears stating that all the above is based on on logic and my own personal experience. I'll gladly defer to anyone who actually tests the thing and who comes up with some solid data.

-don

 

[Cesare57]

It really appears the Fat Duc is hugely popular with only a handful of people not being happy with it. I'm certainly not adverse to a drop in mileage if, as don suggests, you're so happy with the smoothness and crispness down low you yank the throttle a bit more. And I do like to operate in cruiser mode fairly often to enjoy the bike's torque, so if mileage does end up suffering a bit due to a change in my riding habits, so be it!

It's encouraging to know that at least one of you has reaped all the benefits w/o a drop in mpg.

 

[tsmgguy]

We need to remember that these bikes are imported in a configuration offered nowhere else in the world. Ducati made the decision to make the bikes 50 state emissions compliant, including California, with it's infamous CARB. The bikes are sold with stock ECUs that command extreme lean running. That means a great deal of excessive heat and throttle response that is simply unacceptable. Yes, stock gas milage is great, but it's still excellent with the Fatduc installed. It'll still be better than 50 MPG unless you have a very heavy hand indeed!

The Fatduc only slightly enrichens the fuel/air mixture, and then only at the lower RPMs where poor throttle response is most noticable. If you're like me, you don't spend much time at the lower RPMs because the bike's best power and smoothness happen above 4,000 RPM anyway.

So, for $80, you can defeat the CARB and get a bike that is more usable, runs better, and lasts longer because of the real reduction in operating temperatures. You can see this on your temp guage. At least you can make this small mod in locations where motorcycle emissions are not tested annually!

 

[dashzero]

Heat

Where is the data showing that these engines are running hot? And are you referring to the Cylinder Head Temperature or the Exhaust Gas Temperature. Now one seems to talk about Cylinder Head Pressure either.

Also Rich and Lean refer to the fuel/air ratio in relation to Exhaust Gas Temperature. with Rich one one side of the Peak EGT and Lean on the other side of Peak EGT.

If you are in Rich side (˙ before top dead center)in regards to the Timing then leaning it will only raise the EGT and Cylinder head Temperature until a certain point, then it actually starts to drop in temperature, until you reach full lean in which you have NO COMBUSTION, Because there is no fuel in the mixture.

If your timing is after top dead center at full lean, then you temperature would go up as to Enrich the mixture until peak EGT in which the temperature of EGT will start to decline, until reaching a full rich mixture, in which there is only fuel and no AIR, and you will not have any combustion.

Before top dead center timing you can achieve the highest horsepower and torque but at the expense of gas mileage. After top dead center timing you can achieve close to max HP and Torque, but a little better gas mileage.

To close to top dead center timing either on the Rich side (before TDC) or to close on the LEAN side of TDC (after TDC) and the Exhaust gas temperature and Cylinder Head Temperatures will be so high as to limit the longevity of the engine, As well as causing way to high cylinder head pressures.

 

[DUCeditor]

At least you can make this small mod in locations where motorcycle emissions are not tested annually!

Any place, really. 2 minuets with a screw driver and the bike will read like she's stock.

-don

 

[tsmgguy]

Any place, really. 2 minuets with a screw driver and the bike will read like she's stock.

-don

Good point, Don! And no need of a screwdriver.

The canister would probably be a little harder to reinstall as most I'm averse to digging under tons of garbage in the landfill!

 

[bmwson]

FATDUC & Staintune's

My experience with the FATDUC on my GT1000 has been very good. The combination of the FATDUC and Staintune pipes is really good. I have experimented with various settings on the FATDUC ranging from the default setting all the way up to the richest setting. My mileage varied between the low to mid 50’s all the way down to the low to mid 40’s. Also, at the richer settings I sometimes got the yellow engine light if I let the bike idle for several minutes. Another symptom I had at the richest setting was that from time to time my bike would idle around 2000 rpm shortly after taking off in the morning, especially if I did not allow at least two to three minutes of warm-up. I have ended up at a setting about 1/8 of a turn richer than the default. I get very smooth throttle response and when I grab a hand full of throttle the bike roars off really well.

I have a business trip to the US this week and I ordered a K&N air filter which I will bring back and install in combination with a Dietrich’s air box cover I bought on this forum. I am also bringing back a set of Rizoma Lux grips and a Corbin saddle. There seems to be something about this bike that lures me to modify and improve it. Each mod I have made has increased my enjoyment of this machine.

 

[Cesare57]

Well I just bought a slightly used Fat Duc from one of our members who liked it but ended up getting Termis. Once I get it and run it a bit I'll provide some feedback.

Judging by all the great feedback from you guys, I highly doubt I'll be disappointed!

 

[seriousjimmy]

It really appears the Fat Duc is hugely popular with only a handful of people not being happy with it. I'm certainly not adverse to a drop in mileage if, as don suggests, you're so happy with the smoothness and crispness down low you yank the throttle a bit more. And I do like to operate in cruiser mode fairly often to enjoy the bike's torque, so if mileage does end up suffering a bit due to a change in my riding habits, so be it!

It's encouraging to know that at least one of you has reaped all the benefits w/o a drop in mpg.

A gentleman by the name of Artisto once said to me "If you're worried about your bike's gas mileage, get a Prius."
Well, I DID get a Prius...
I also drilled holes in my GT's pipes, changed the sprocket toothage and installed a Fatduc. Low rpm/speed vibey-and-juddery-ness was substantially reduced, seat of the pants power increased nicely and I'm STILL getting 45 to 50mpg ALL THE TIME. Do it all and enjoy. And after that 7500mi svc...
By the way, the Prius gets 45mpg...ALL THE TIME, too...

 

[DUCeditor]

The canister would probably be a little harder to reinstall as most I'm averse to digging under tons of garbage in the landfill!

My response would be "Hey, you wanna see something ugly on the bike? Have a seat."

-nod

 

[Cesare57]

Lovin' the Fat Duc!

Received it last night and snapped it in easily with the help of installation pics on webbikeworld. Took it out for a 15-20 miler after dinner and noticed the low speed, low gear smoothness right away. Really eliminated that jerkiness we're all familiar with.

Tried to ride to work this a.m. but turned around after about 4 miles due to really dense fog. However, on the way back home to get the cage I drove through some neighborhoods for safety's sake and had to go through a couple of 20mph school zones. It was like being on a different bike! Before, it was really uncomfortable trying to maintain a smooth 20 in either 1st or 2nd. Now it's a piece of cake.

I really appreciate how the Fat Duc brings out the bike's "inner cruiser" by letting you do the low speed lope\short-shift thing around neighborhoods, and 1st\2nd gear corners are much smoother too.

I've got it set about at about 13.4 right now, but will probably play with different settings just to see how they feel. Definitely feels like money well spent!