[chrisp]

Wanted to hit the forum to see if anyone has noticed any long term issues with the Fat Duc 02.
I had a mechanic tell me to stay away, but I’ve also heard a lot of good things about them.
I’m running stock exhaust, and will never run Termis, but may run Staintunes in a bit.

 

[mlukason]

I used one on my ST3 for a couple years. It did smooth out the lean running issues. Eventually I had to replace the ECU so I didn't need the Fat Duc any longer. I had no issues with it.

 

[Duccout]

I've been running mine for about 9000 miles, no problems. bike was awful at low speed without it.

 

[ncgt1000]

I've had one on my '07 GT since '08. No issues other than it runs so much better. Also running Staintunes and a K&N air filter with the top of the air filter box opened up.

 

[Pro69ss]

I just ordered some for my new to me 11 Multistrada and a servo eliminator cable . I think between both, my problems will be solved hopefully.The bike has plenty of power and runs amazing while twisting the throttle, just not so much cruising.

 

[Slowdive]

I had one on my GT. It made things slightly better. If I wound it up too rich I got a CEL.

I think they are less effective on a narrow band O2 sensor setups. The FatDuc is simply a resistor bridge which attenuates the entire response curve. In theory the FatDuc should do little good, but because the stoichiometric is on a steep slope, you can change the AFR a little bit, but nowhere near enough to get to 13.5:1 AFR which seems like the sweet spot on Ducs. I now have an open loop system (DP ECU w/ Wasp PUK) which others say is ~13.6:1. Much much better fueling than I ever got with the FatDuc.

 

[lerceg]

Just before winter, I was having issues with my '07 GT1000. Seemed like the throttle would get stuck open when I would stop. Later the bike started to idle low and die. Took to Motowerks in Chicago. They told me it was my plugs. I just put in new plugs 3 months before. He showed me a pic of them fouled up. The mechanic said it was the Fat Duc causing it. He took it off and installed new plugs. Still have issues of bike cutting out at stops after it warms up. Taking to another shop soon.
My question: Does the Fat Duc have an expiration? Can it go bad? I installed it back in '08 and it ran great. Maybe a new Fat Duc would fix the problems.

running stock pipes

 

[mlukason]

I guess since it's an electrical component, it could go bad. You can test it with a multimeter set to read resistance. Turn the potentiometer screw and see if the resistance changes.

 

[mike_delphin]

Just before winter, I was having issues with my '07 GT1000. Seemed like the throttle would get stuck open when I would stop. Later the bike started to idle low and die. Took to Motowerks in Chicago. They told me it was my plugs. I just put in new plugs 3 months before. He showed me a pic of them fouled up. The mechanic said it was the Fat Duc causing it. He took it off and installed new plugs. Still have issues of bike cutting out at stops after it warms up. Taking to another shop soon.
My question: Does the Fat Duc have an expiration? Can it go bad? I installed it back in '08 and it ran great. Maybe a new Fat Duc would fix the problems.

running stock pipes

Might need to get your valves adjusted.

 

[Slowdive]

My question: Does the Fat Duc have an expiration? Can it go bad? I installed it back in '08 and it ran great. Maybe a new Fat Duc would fix the problems.

running stock pipes

I guess since it's an electrical component, it could go bad. You can test it with a multimeter set to read resistance. Turn the potentiometer screw and see if the resistance changes.

Um, yeah this. This would be an exhaustive test...

4-4: Short
3-3: Short
2-2: Short
A: 20k Ohms
B: 12k - 17k Ohms (5k Pot)
C: 32k - 37k (5k Pot) - redundant test, but why not?