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Discussion Starter · #1 ·
Team, have a question regarding the more simple ‘fuel’ controllers such as RB Easy (etc) and the new Fuelx, in particular the units which interrupt the o2 sensor to gain the fuel control.

These controllers are somewhat marketed as a good option to smooth out the bike and to allow for minor modification I.e exhaust/ intake - specifically the Fuelx mentions this. I just installed the Fuelx lite this morning and went for a quick blat, definitely much nicer bike to ride in traffic/ slow etc. and power delivery seems much smoother.

My question is, if the o2 sensor is on the closed loop, would this mean I am only able to run ‘richer’ while in the closed loop and as soon as I crack the throttle open and enter open loop I just go back to standard fuel map and start running lean - assuming I had made an exhaust/ air intake upgrade? Or does the engine’s MAP sensors etc take over in the open loop to add fuel to compensate for increased airflow due to mods and ensure the AFR is within tolerance - even if this was at the stock level of lambda 1, rather than leaner?
 

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Most all KTM's have the tendency to run rich in the open-loop.
The FuelX, Coober LM, Dimsport units mostly manage the O2/Lambda sensor readings in the closed-loop as there is no necessity to alter the readings in the open-loop as the OEM ECU is no longer instructed/restricted by the O2/Lambda sonde readings.
From what I've read (and this is basically the same for the Dimsport units) the FuelX initially is on a learning curve so it will take time to fine-tune and function to its best capability after a while. (Dimsport claims approx. 200 km).
This will again be the case when you alter anything in the air-flow track (intake and/or exhaust).
 

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Discussion Starter · #3 ·
Most all KTM's have the tendency to run rich in the open-loop.
The FuelX, Coober LM, Dimsport units mostly manage the O2/Lambda sensor readings in the closed-loop as there is no necessity to alter the readings in the open-loop as the OEM ECU is no longer instructed/restricted by the O2/Lambda sonde readings.
From what I've read (and this is basically the same for the Dimsport units) the FuelX initially is on a learning curve so it will take time to fine-tune and function to its best capability after a while. (Dimsport claims approx. 200 km).
This will again be the case when you alter anything in the air-flow track (intake and/or exhaust).
Thanks mate! So the Fuelx should be sufficient to ensure I don’t run too lean with the aftermarket exhaust and air filter then, given the OEM ECU will take care of the open loop? I must admit I was surprised at how different (much better) the bike performed after fitting the Fuelx so if that gets even better with time then that is even more impressive. Was very jerky/ uncomfortable. The only thing I did notice was the reduced engine breaking, which might catch someone off guard straight after changing it, quite surprising how much this has been reduced - much smoother though and less aggressive.
 

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Yes, should be fine unless you take the airbox off and install a cone/ram filter with a fully open exhaust I think.
As for the upgrade in air filter, have a look at DNA or BMC as these are better manufactured.
For the DNA filters (on the first-Gen bikes) you even have a choice of 2, a road and a race version.
 

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Was exceptionally jerky/awkward. The main thing I saw was the decreased motor breaking, which may surprise somebody straight in the wake of evolving it, very amazing how much this has been diminished - much smoother however and less forceful.
 

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My question is, if the o2 sensor is on the closed loop, would this mean I am only able to run ‘richer’ while in the closed loop and as soon as I crack the throttle open and enter open loop I just go back to standard fuel map and start running lean - assuming I had made an exhaust/ air intake upgrade? Or does the engine’s MAP sensors etc take over in the open loop to add fuel to compensate for increased airflow due to mods and ensure the AFR is within tolerance - even if this was at the stock level of lambda 1, rather than leaner?
Thanks, I had the same question; Jens Lyck at Boosterplug puts out a full booklet, free on their website. This insists that fiddling with the O2 sensor cannot touch open loop, so cannot fix the jerky fuelling at varying throttle openings.
Despite this several folk report the 390 much improved (I run a Svartpilen 401 but same motor and systems). Have ordered the FuelX Lite as don't need more performance, but unhappy with traffic and tight corner jerky throttle response.
Also run a fuel injected Ultralight aircraft, these tend to have constant steady throttle opening so the Lambda rules all.
Sensor kicks in after short time at steady throttle, assume the KTM ECU set to a very short time indeed.
Lack of engine braking is an interesting side effect, assume it has total fuel cut off as standard, and the FuelX keeps a trickle going?
 

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Team, have a question regarding the more simple ‘fuel’ controllers such as RB Easy (etc) and the new Fuelx, in particular the units which interrupt the o2 sensor to gain the fuel control.

These controllers are somewhat marketed as a good option to smooth out the bike and to allow for minor modification I.e exhaust/ intake - specifically the Fuelx mentions this. I just installed the Fuelx lite this morning and went for a quick blat, definitely much nicer bike to ride in traffic/ slow etc. and power delivery seems much smoother.

My question is, if the o2 sensor is on the closed loop, would this mean I am only able to run ‘richer’ while in the closed loop and as soon as I crack the throttle open and enter open loop I just go back to standard fuel map and start running lean - assuming I had made an exhaust/ air intake upgrade? Or does the engine’s MAP sensors etc take over in the open loop to add fuel to compensate for increased airflow due to mods and ensure the AFR is within tolerance - even if this was at the stock level of lambda 1, rather than leaner?
Received FuelX Lite yesterday, fitting is straightforward, connectors etc are very high quality, easily match factory harness and connectors. Note, when connecting O2/Lambda Sensor plug it won't push in straight away as you'd expect, with clip merely locking the connector. You assemble but DON'T force it, (luckily didn't try) then close big orange retaining clip which acts to push connectors together and lock them. Result:- at first short ride running slow until up to temperature little difference, as ride progressed with mixed urban and country, throttle response grew smoother, bike no longer jerking and hunting on slow corners. After 76 miles bike felt totally different, able to pull smoothly even if too high a gear was selected. Check miles per UK gallon came out at 58mpg, a little worse than the 70mpg or so others report, but well worth small loss. Only stalled once turning in a narrow road (my fault) whereas would usually have three or four 'events' on a normal ride. It isn't smart to run a big single too slowly, but with the FuelX lite added it allows the odd less than ideal gear selection.
 

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Most all KTM's have the tendency to run rich in the open-loop.
The FuelX, Coober LM, Dimsport units mostly manage the O2/Lambda sensor readings in the closed-loop as there is no necessity to alter the readings in the open-loop as the OEM ECU is no longer instructed/restricted by the O2/Lambda sonde readings.
From what I've read (and this is basically the same for the Dimsport units) the FuelX initially is on a learning curve so it will take time to fine-tune and function to its best capability after a while. (Dimsport claims approx. 200 km).
This will again be the case when you alter anything in the air-flow track (intake and/or exhaust).
I ordered the Fuel X pro it was on sale. I've heard level 3 is stock others say 6. I kinda think the lite might be better. Yes I can choose higher levels of fuel . But how do I make that choice . I am curious exactly when does closed loop end. Bike should gain a little torque and horsepower in bottom and mid range. I usually ride near 6k. So I think it's perfect . The fastest road anywhere near me is 70. And if I speed it's only brief . Has anyone put the fuel X on the dyno ?
 
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