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Hi i have just purchased a 2018 790 duke are they all jerky when riding around town at 30 mph the bikes fitted with a decat pipe and scorpion end can. is there a way to smooth it out? i also have a z1000 sx and thats not like this
 

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I found that riding in sport mode is easier. That's the bike's fueling. You can get used to it or change it (PCV, flash, etc.). Lots of discussions in the Tuning section.
 

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2020 790 Duke, 2006 SV 650, 2008 Hot rodded KLR, 1991 Honda Hawk NT 650
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Hi i have just purchased a 2018 790 duke are they all jerky when riding around town at 30 mph the bikes fitted with a decat pipe and scorpion end can. is there a way to smooth it out? i also have a z1000 sx and thats not like this
The Booster Plug.
 

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Hi i have just purchased a 2018 790 duke are they all jerky when riding around town at 30 mph the bikes fitted with a decat pipe and scorpion end can. is there a way to smooth it out? i also have a z1000 sx and thats not like this
Unless it has a PCV by Rotty or ECU flashed by a dyno tuner, you can't expect it to ride right with that exhaust configuration.

EDIT: Yes these bikes are a bit jerky at low speeds... but 30... no I don't get any jerkiness around that speed. More like 15-20 mph.
 

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Hi i have just purchased a 2018 790 duke are they all jerky when riding around town at 30 mph the bikes fitted with a decat pipe and scorpion end can. is there a way to smooth it out? i also have a z1000 sx and thats not like this
Hi, Get yourself a Boosterplug out of Denmark for like $160. Easy install in 15-mins. It will fatten up the air/fuel mixture, as your bike is running too lean for Euro-4 emissions BS. Perhaps your Kawasaki being Japanese doesn't have to meet those emissions just yet. Cheers from west Canada.
 

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Some owners (me included) have replaced the front 16 tooth sprocket with a 15T to lower the gearing slightly. I'm not convinced it made much difference to the low speed jerkiness, but others have found it helps, so it might be worth a shot.
 

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I see Boosterplug being touted as a cure for the low speed stumbled.

I had one for awhile and noticed only a small improvement. I wound up selling it and don't miss it.
 

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I see Boosterplug being touted as a cure for the low speed stumbled.

I had one for awhile and noticed only a small improvement. I wound up selling it and don't miss it.
Hi Columbo, not sure why results can be variable but my 790D much happier at idle, steadier on v light throttle and improved in other ways too. Cheers
 

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None of this is hard to explain.

The simple fact is that this bike has a crank with low inertial mass. So requires rotational speed to gain stability. This is however what makes it rev so readily.
(Note that KTM have indeed increased the inertial mass by 20% on the 890ADV crank for this reason - in part at least)

And lest we forget it has a deliberate offset firing cycle. I've been riding V-twins most of my adult life - it's just how they are.

Also it is notoriously difficult to control the fueling of almost any engine (but moreso an engine with uneven firing cycles) in the 0-5% TPS range. 1% difference in butterfly angle makes a big difference to laminar air flow. it is not linear.

Options :

Well if you increase the RPM/speed ratio then you get better rotational stability. The 15 tooth Sprocket will help a bit. I have this done. It helps - a bit.
Booster plug - well this will basically soften the ignition part of the firing cycle. Smoother but very likely less grunt at low TPS. It's a trade off.
PCV/COOBER/REFLASH - Well I doubt they are addressing the "trundling in traffic" dilemma. Help? - Yes!. Solve? - No. I have a COOBER - It helps - but it's not the problem it excels at fixing.

Rain mode - very much an option if you do not have a sensitive throttle hand. I find it most certainly helps on those very rare days when I ride with lined winter-ish gloves. Usually I am in SPORT.
 

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Good writeup, barbagris. Thanks!

I actually found the the sport mode feels less snatchy to me at low speeds. I guess is has to do with the fact that is picks up butterfly angle quicker.
 

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Hi i have just purchased a 2018 790 duke are they all jerky when riding around town at 30 mph the bikes fitted with a decat pipe and scorpion end can. is there a way to smooth it out? i also have a z1000 sx and thats not like this
Congrats. Mine is a stock 2020 and is jerky in low speeds up to about 45, it’s just the way they are. I find street mode is the least jerky, some owners ride urban traffic in rain mode, but that doesn’t work for me. I have read that the upgraded electronic fuel controller offered by KTM made by Coober does solve the problem, but it is expensive +$500. So, I haven’t bought it to find out. My dealer told me they could just “de cat“ it but that’s not for me either, and with a new exhaust it’s just as, if not more, expensive than the Coober. Feathering the clutch in heavy traffic in street mode is about the best I’ve been able to come up with. Good luck let us know if you solve it. Thx, jdb.
 

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Hi i have just purchased a 2018 790 duke are they all jerky when riding around town at 30 mph the bikes fitted with a decat pipe and scorpion end can. is there a way to smooth it out? i also have a z1000 sx and thats not like this
my fix for that is to go to rain mode in traffic = after you're out of town put it back in your favorite mode
 
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