Fat Duc O2 Manipulator
No, you don't get a free Nikon 18-200 VR
with the O2 Manipulator!
Fat Duc O2 Oxygen Sensor Manipulator
by Rick K. for webBikeWorld.com
Maintenance and Repair Article Index |
Blog Home | Owner Comments (Below)
by Rick K. for webBikeWorld
A few weeks ago I received a breviloquent email from
"Jason" at Fat Duc:
"Just wanted to make you aware of a new product that
we're seeing great results in curing many of the low RPM
problems plaguing late model Ducatis.
The Fat Duc O2 Manipulator is a simple, yet effective
way to alter the closed loop air-fuel ratio and
reduce/eliminate popping on decel, improve throttle
response and reduce surging."
OK Jason, you snagged me. "Sounds interesting",
I thought. But I don't have this problem, right?
I cured it with the installation of the "Euro" ECU and
the 14-tooth sprocket on the GT1000, no?
Some sniffing around the forums turned up a gaggle of
SportClassic owners who have tried everything but were still
complaining about the surging, hiccoughing, popping,
snapping and hair-trigger throttle response that seems
to be endemic to Ducati SportClassics of every type,
even after an ECU transplant.
I was getting a pop here and there, but nothing like it
was before I brought the GT1000 to the ace mechanics at Duc Pond Motorsports in Winchester, Virginia, where
somehow or another Donnie Unger talked Ducati NA into
forking over a replacement Euro ECU under warranty.
I covered this almost one year ago in my "Ducati GT 1000 ECU, Throttle
Body Balance and Lean Running Fix" article, and
never looked back -- I've been having too much fun
riding the now-transformed GT1000.
The ECU and a 14-tooth sprocket I had them install transformed the bike, but I will admit
to a throttle response that still could be a bit smoother and
lumpy idle that sounded like gremlins were
shoveling in gas a spoonful at a time.
So why not take Jason up on his offer? I had no
idea what an "O2 Manipulator" was -- O2 is oxygen,
right? And tell me again why I'd want to
manipulate it? And besides, isn't this thing in
the same category as those wacky carburetor vortex
generators and fuel atomizers?
I was all ready to call Jason's bluff on this one.
The thing arrived a few days later in a tiny package.
It's a very
professional-looking wiring harness (photo above) with
simple instructions and a simpler note: "I think you'll
be amazed with the changes even with a stock exhaust.
You'll want to set it somewhere between a 13.5/1 -
The silver dot on the O2 Manipulator screw is the
richest setting (highest Voltage reduction).
The Fat Duc O2 Manipulator is apparently some type of
electronic gizmo that's way beyond my level of understanding.
It manipulates (makes sense, right?) the O2 and, I
guess, fakes out the ECU into believing those gremlins
are on holiday.
The device has a tiny little screw that allows "AFR"
settings (which I assume means Air/Fuel Ratio?) between
13.0:1 and 14.2:1, according to the diagram on the
single page instruction sheet.
Don't ask me why,
how or what this is all about -- all I did was follow
Jason's instructions, and turned the screw until it
looked like it was between the 13.2 and 13.5 setting he
After playing with the O2 Manipulator, I threw it on
the shelf in the garage, where it bounced
around for a couple of weeks, nearly
forgotten. Then the weather turned fall-beautiful
again, so it was time to give it a whirl.
But first, the install. As it turns out, the hardest part is tracing the
wiring harness from the bike's O2 sensor; it's the only
thingie plugged into the exhaust that has a wiring
harness leading up into the guts of the bike.
2007 Ducati GT1000 oxygen sensor, plugged into
Stock GT1000 connector; this is where the Fat Duc O2
Manipulator is plumbed in.
Post Fat Duc O2 Manipulator installation, with the two
connectors tucked in to clear the seat.
I traced the harness a few times to make sure I had
it right and discovered that it ended in a connector
right under the seat of the GT1000 (see photo).
I'm not sure if it's the same with any of the other
SportClassics, but it shouldn't be hard to find, once
you start at the O2 sensor.
It took me literally 10 seconds to plum the new
harness into the system and tuck it in -- once I found
it, of course. "OK, now we'll see", I thought --
pretty smug, thinking this entire exercise would
be a flop.
But as soon as I started the bike, I could sense
something different. Was it me? Or did
it start quicker and jump immediately into a nice,
Where's the lumps??
Earplugs in; helmet and gloves on as the bike was
warming up, then I hopped on and pulled away. Wow!
The throttle feels so...smooth! I noticed the
Tearing around the back roads revealed the truth --
this little manipulator gizmo has brought the bike to a
whole new level of driveability.
Forget the lumpy idle and backfiring, which had been
pretty much eliminated with the new ECU and 14-tooth
sprocket combo anyway. I could live with that.
What I really notice is that the bike now has an
incredibly smooth throttle response -- like no other
fuel injected bike I've ever been on. The little
bit of on/off response, which even after the ECU
transplant still reared its head after rolling on the
gas when turning into a slow corner is completely gone.
The only way I can describe it is like going from
Coltrane's Interstellar Space back to Blue
Train. Smooth, baby, smooth.
Here's where I can really tell the difference: I
always ride with two digits on the shorty brake lever
and I've trained myself to goose the throttle
simultaneously with braking, when I'm double-clutching
I also like to hold or roll on the throttle while I'm
braking and entering a corner to smooth out the
transition and get on the gas quicker on the exit, a
trick I learned in
Lee Parks' Total Control Advanced Riding Clinic.
This is a hard trick to get right, made doubly so on
the GT1000, nearly impossible with the stock ECU and
difficult even with the ECU changes on the Duc.
But now it's like buttah baby; no problemo! I'm
pretty astounded actually -- it's really like a big, fat
mellow filter has been draped over the throttle.
The engine has lost every bit of the raw harshness that
it had before. You can still tell it's a Duc, but
I have no idea if I just happened to hit the sweet
spot when I twisted the screw on the O2 Manipulator, but
I'm not about to change a thing to test it, sorry!
It's just right as it is and I'm not going to take a
And here's something else -- even with the 14-tooth
sprocket, I could almost never preivously get the bike
into 6th gear at anything under about 75 MPH. And
since I don't ride on open roads or freeways, I'm
usually down in 3rd and 4th max on the twisty country
ribbons that start right outside my front door.
But lo and behold, I find myself in one or two gears
higher than before, sometimes completely faked out,
toeing up the lever, thinking it must be a mistake -- I
simply can't be in 6th gear, right?
I can now take it all the way down to about 3k RPM in
6th gear, about 45-50 MPH, and it will pull right up to
redline without a complaint as I twist the throttle.
Sure, there's a bit of bumping from those big 500 cc
pistons winging through their way back and forth through
the 90 degree cylinders, but not a spot of the lugging
and chugging and coughing that would make this a
definite no-no before the O2 was, well, manipulated.
Now here's the disclaimer: I have the Euro ECU and
the 14-tooth front sprocket installed, but nothing else
has been changed on the bike. Stock mufflers,
everything stock. I use Shell Premium fuel always.
Other than that, nada. And I've done no
"scientific" testing at all on this -- it's all in what
my wrist and little grey cells tell me.
By the way, I/we have no relationship with Fat Duc,
financial or otherwise. Jason sent us a sample
gratis and that's it.
The Euro ECU and 14-tooth sprocket made a world of
difference on the GT1000 -- I thought this was as good
as it was going to get.
But my opinion is the Fat Duc O2 Manipulator is to
the Euro ECU as the Euro ECU was to the original, harsh,
on/off throttle and backfiring that plagued the bike
right from the factory. About another 100%
I don't know if the Fat Duc O2 Manipulator would do
the same for a stock SportClassic, but for 80 bucks and
-- get this -- a 30-day return policy, how can you go
wrong? I'll bet the savings in fuel from being
able to ride 1-2 gears higher than normal will pay for
the thing in no time.
But don't ask me to measure the fuel mileage -- I'm
having too much fun riding! Next stop: Staintune!
Fat Duc O2 Sensor Manipulator
Suggested Retail Price: $80.00 + S/H
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From "J.G." (4/09): "Thanks very much for
working so hard producing a quality web site, I really
appreciate it. It has been a great resource for me.
I wanted to chime in on the Fat Duc 02 Manipulator,
it has made a big difference in how my 2007 GT1000
performs. When I first bought my GT1000 the
gearing was too high and the throttle response was very
edgy. I made a couple of changes to improve
I replaced the front sprocket with a 14 tooth
sprocket which made the bike usable in city traffic and
my dealer replaced my ECU with a Euro ECU. This
made a huge difference in the way the bike performed.
The gear range was finally appropriate for mixed city
and highway driving and the throttle response was much
However, there was still an on/off throttle response
that bothered me in stop and go traffic and when
throttling up coming out of corners.
I read about the Fat Duc 02 Manipulator on your web
site and thought, for $80, it was worth giving it a try.
Installation was a breeze and your photos on the web
site made it even easier.
You could tell it was working immediately. The
strange loping idle was gone, replaced by a smooth,
steady idle. The on/off throttle response has been
really smoothed out but, I still find myself being extra
cautious applying throttle coming out of corners out of
well ingrained habit (I suspect I’ll get over that
soon). I didn’t expect highway riding to change
but, I was really surprised to find myself comfortably
in sixth gear at 65 mph. I have never seen sixth
gear before under 80 mph.
The change I like the most is that the bike just
seems easier to cruise with. Before the 02
Manipulator I just could not stand following traffic,
the bike had certain speeds it wanted to cruise at and
was uncomfortable cruising at other speeds. I
found myself passing vehicles all the time.
Now it seems that the range of comfortable cruising
speeds has widened and I find myself less inclined to
pass. This will help me retain my license.
This was the best $80 I have ever spent on a motorcycle.
I would highly recommend this for anyone with this
From "Duceditor", the Editor at
Unlimited Connection (11.08): "I was among
those who had the privilege of testing the 02
manipulator during its experimental stage. The
unit was fundamentally the same as the one being sold
except that the parts were hand soldered and thus,
potentially, not as durable as the final, 'for sale,'
My findings, like almost everyone else who has tested
this little gizmo, matched your own. For a mere
$80 the bike's "carburetion" went from barely passable
to perfection. I, too, was simply amazed.
My bike is almost stock, the two exceptions being the
modified cans you commented on in an earlier
webBikeWorld posting, and the now almost de rigueur 14
tooth front sprocket. Thus I can comment that
there will be the same extraordinary results with the
Have no fear about tweaking the dial on the
manipulator. There is no magical "sweet spot,"
just small changes as the f/a mixture is enriched a bit
more or less.
I settled on the setting that is said to indicate a
13.2/1 ratio. This is technically a bit rich, at
least at idle - I can tell by the smell of the exhaust -
but is absolutely buttery smooth, possibly because the
said "richness" hides any imperfections in the F/I
balance between the cylinders.
Nothing, of course, comes without some cost, and in
the case of the 02 manipulator that cost shows at the
fuel pump, which is now more in line with what one might
expect with a high performance 1000cc twin - high
thirties to mid forties MPG (depending on how
enthusiastically one rides). This in comparison to
the low fifties the over-lean stock setup gave.
Still, all it would take to get the MPG back up there
is 10 seconds with a screw driver. Dialed all the
way from the silver dot voids out the unit, i.e., you
are back to 'stock.' If I was doing a full day on
the superslab (heaven forbid) I might do that to extend
the per-tank distance capability.
Thanks for giving such in-depth coverage to the
GT1000. As a fellow GT owner I reference your site
From "J.M." (10/08): "I just got the
Fat Duc and thanks to your excellent pics, installation
was accomplished in minutes. I also have the 14
tooth sprocket with the Euro ECU and (with those
improvements only) the bike ran much better than stock
but still popped back a lot on the over run.
That has now been completely eliminated and the
difference in overall smoothness is very pronounced.
I will give it a good test this weekend but I have to
say I already feel it was well it worth the money.
From "J.C." (10/08): Bike: Stock
Ducati GT1000 but with accessory clutch master cylinder.
"Well I got it yesterday, and rode the bike to work
today (all the way from [Northern Virginia], brrrrr,
cold). I set it to what you have (between 13.2 and
13.5) and it took me < 1 minute to put on (since you
nicely already did the tracing part). Well I can
definitely say, it works.
First for the harsh on/off response, it definitely
makes a difference. Not huge, but a difference.
I really noticed it in the stop and go traffic that sit
in from Rt. 236 to I-66 on the Beltway. It was a little
Now, not that it is totally smooth, if, say the stock
GT1000 was a 1 and my smooth as silk clutch W650 is a
10, I would say its now a 3. So to me that
combined with the new (hydraulic clutch master cylinder
and lever) make it much more manageable. Still no
where as nice as the (Kawasaki) W650, but the total
stock clutch was unusable in traffic, now it's a bit
easier and a bit smoother.
But the other funny thing was I was now riding at
60-70mph in 6th gear and it felt 'right'. Before I
would have to be going >75 to even put it in 6th and
have it feel right, but now I can do the interstate in
6th. Not really sure if it affects the feel of the
other gears, I didn't notice any other shifting
differences, but it nice to have a useful 6th gear.
Not really sure how this works as the gearing is not
So I assume the downside to this is that I probably
have lost a little power and maybe top speed? If
so I don't care, this bike had 3x the power of any I
have ever had and I am not racing it, and for top speed,
if it is down it will still be much higher then I will
ever take the bike! Also don't really care if it
might hurt gas mileage a bit.
Overall, a definite keeper. For $80 (and the
easiest install of an upgrade ever), certainly makes
enough of a difference to be worth the money. I
probably will play with the settings some to see what
difference it makes and if it can get better, will tell
you if I find anything different."