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I see the rapid bike easy was talked about, I made a thread that outlines a fair amount of information on the RBE to included Air Fuel Ratios.
Do you have a link? I couldn't find when searching .

http://www.ktmduke390forum.com/foru...ping-shouldn-t-ktm-s-job-2.html#/topics/39849

Thanks. Useful stuff. Still seems a bit lean WOT for what I have experienced as best afr for power on other bikes (12.8 to 13) but it looks like rapid bike evo would allow the flexibility for tuning that.
 

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Thanks. Useful stuff. Still seems a bit lean WOT for what I have experienced as best afr for power on other bikes (12.8 to 13) but it looks like rapid bike evo would allow the flexibility for tuning that.
I agree, you should see the OEM AFR's....
 

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I remember the Yamaha XT500 from many years ago (about 1985) with the thud-thud-thud engine. I would have expected that the almost 400cc KTM should be able to do the same - lots of power with low revs. But maybe it has to be one or the other, high or low rev optimization, even with a modern bike?
There is a basic difference between the old XT engine and the Duke - Bore & Stroke.
The XT has a much longer stroke which equals more torque, and that's delivering the solid pull at low revs you experienced.

XT 500 87 mm × 84 mm
KTM 390 89 mm × 60 mm

The 390 piston is actually bigger than the XT500, but it has a very short stroke as a ratio of piston size.
The result is a short duration between each power stroke and the ability to build revs very quickly.

There will be a whole bunch of other factors, but since your question was aimed at learning and understanding I thought this basic difference might be of interest :)
 

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Discussion Starter #24
There is a basic difference between the old XT engine and the Duke - Bore & Stroke.
The XT has a much longer stroke which equals more torque, and that's delivering the solid pull at low revs you experienced.

XT 500 87 mm × 84 mm
KTM 390 89 mm × 60 mm

The 390 piston is actually bigger than the XT500, but it has a very short stroke as a ratio of piston size.
The result is a short duration between each power stroke and the ability to build revs very quickly.

There will be a whole bunch of other factors, but since your question was aimed at learning and understanding I thought this basic difference might be of interest :)

Thanks Andy. I appreciate your information. I know the basic principle and I should have looked up those numbers. But somehow I thought 500cc one cylinder bike must be similar to 370cc one cylinder bike. I was wrong in my assumption and now I know why. Thanks!
 

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I keep seeing everyone refer to the OEM fuel cal as 'lean', but what AFR numbers are people seeing at what load to make that determination? Leaner = more power, better fuel economy, and better emissions (to a point), so adding fuel should realistically take power away if it's as bad as everyone keeps inferring. And if it's really that lean then how have the KTM engineers messed up so badly?

Has anyone actually seen the tuning/maps for the 390 or have any relevant datalogs?
 

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I keep seeing everyone refer to the OEM fuel cal as 'lean', but what AFR numbers are people seeing at what load to make that determination? Leaner = more power, better fuel economy, and better emissions (to a point), so adding fuel should realistically take power away if it's as bad as everyone keeps inferring. And if it's really that lean then how have the KTM engineers messed up so badly?

Has anyone actually seen the tuning/maps for the 390 or have any relevant datalogs?

Sadly I don't have the WOT AFR's on the stock tune.
During light cruising say 20-40% throttle I was seeing 14.8-15.1 AFR's and a Idle AFR of 14.1
The only modifications I had at the time was a drop in K&N filter, on 91 octane, at sea level.

After fitting the rapid bike easy I was seeing the following:
Idle AFR 13.4
Driving AFR: 13.8-14.0
WOT AFR: 13.8

All of this was utilizing the Bluetooth adapter and torque app to measure AFRs.
 

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I keep seeing everyone refer to the OEM fuel cal as 'lean', but what AFR numbers are people seeing at what load to make that determination? Leaner = more power, better fuel economy, and better emissions (to a point), so adding fuel should realistically take power away if it's as bad as everyone keeps inferring. And if it's really that lean then how have the KTM engineers messed up so badly?

Has anyone actually seen the tuning/maps for the 390 or have any relevant datalogs?
I cannot comment on exactly what afr the duke 390 runs as I havent personally seen the data other than what people post here. But I work in engine/vehicle calibration in the automotive industry for some time so i can tell you what I think they will be running. Lambda 1 or 14.7 afr, is best for fuel economy. Furthermore, most recent emissions legislation is now stipulating that the industry can only enrich for component protection. If a vehicle manufacturer can't prove with data that their exhaust valves will burn out unless they run rich of lambda 1, then they have to run lambda 1 everywhere they can even though its not best for power. 0.85 to 0.9 is normally best on a naturally aspirated engine for power. In addition, some engines (like this one) also like to be a bit richer at part load for driveability improvement. So both these reasons are why the aftermarket continues to see benefits by running richer compared to an OEM like ktm.

If the Oems were allowed to, they would run richer but they are constrained by the emissions rules, and to a lesser extent, also the fuel economy benefit they can offer to the customer.
 

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Sadly I don't have the WOT AFR's on the stock tune.
During light cruising say 20-40% throttle I was seeing 14.8-15.1 AFR's and a Idle AFR of 14.1
The only modifications I had at the time was a drop in K&N filter, on 91 octane, at sea level.

After fitting the rapid bike easy I was seeing the following:
Idle AFR 13.4
Driving AFR: 13.8-14.0
WOT AFR: 13.8

All of this was utilizing the Bluetooth adapter and torque app to measure AFRs.
That's kind of what I've been assuming based on what I've read. Your stated 14.8-15.1 AFR's for light cruise is completely normal and correct, though 14.1 idle is pretty rich. Obviously you're not getting the most accurate info by using Torque, though it's better than nothing. Your AFR's after fitting the RBE are obviously all wrong, both too rich in idle/cruise and too lean during WOT.

Obviously it's not hard to pull lambda numbers off the internet but enrichment past MBT (or at least MRT) is a waste and is just going to be lost power/economy. Also, 1 lambda is not 14.7:1 for any fuel other than E0, which is becoming increasingly difficult to find these days. I hate having to bring that up but most people that try and correlate 1 lambda to 14.7:1 AFR just don't actually understand how lambda correlates to the stoichiometric value of a given fuel. Seems how stoich of E85 is 9.8:1, the exact same .85 lambda command would enrich it to 8.3:1 when compared to the E0's 12.5:1.

Anyways, I suspect a lot of the information related to Duke AFR's is probably just not the most accurate here. What options are there for datalogging? Are there any?
 

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So based on the the comment here. In order to fix the stalling, jerkiness, lean conditions the 390 Duke has out of the box.
Your best bet is either a re-map or Piggyback ECU (preferably ones with auto tune) like Power Commander 5 w/ Autotune or RapidBike EVO.
I've been having the common stalling issues on my 2017 ever since i got it and now it has 1200 mile or so on the clock.
Checked all my valve clearances twice and all within spec. Just ordered a RapidBike EVO so hopeful this will get me riding smooth.
The RapidBike EASY is also another cheaper option but you have to set setting manual so no auto tune like the EVO.
 

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Sadly I don't have the WOT AFR's on the stock tune.
During light cruising say 20-40% throttle I was seeing 14.8-15.1 AFR's and a Idle AFR of 14.1
The only modifications I had at the time was a drop in K&N filter, on 91 octane, at sea level.

After fitting the rapid bike easy I was seeing the following:
Idle AFR 13.4
Driving AFR: 13.8-14.0
WOT AFR: 13.8

All of this was utilizing the Bluetooth adapter and torque app to measure AFRs.
That's kind of what I've been assuming based on what I've read. Your stated 14.8-15.1 AFR's for light cruise is completely normal and correct, though 14.1 idle is pretty rich. Obviously you're not getting the most accurate info by using Torque, though it's better than nothing. Your AFR's after fitting the RBE are obviously all wrong, both too rich in idle/cruise and too lean during WOT.

Obviously it's not hard to pull lambda numbers off the internet but enrichment past MBT (or at least MRT) is a waste and is just going to be lost power/economy. Also, 1 lambda is not 14.7:1 for any fuel other than E0, which is becoming increasingly difficult to find these days. I hate having to bring that up but most people that try and correlate 1 lambda to 14.7:1 AFR just don't actually understand how lambda correlates to the stoichiometric value of a given fuel. Seems how stoich of E85 is 9.8:1, the exact same .85 lambda command would enrich it to 8.3:1 when compared to the E0's 12.5:1.

Anyways, I suspect a lot of the information related to Duke AFR's is probably just not the most accurate here. What options are there for datalogging? Are there any?
Here in Europe we have no problem finding e0 fuel actually. Most of it still is;-)
 

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Discussion Starter #32
Here is an interesting video which explains lean and rich and different fuel types etc.


Air/Fuel Ratio - How Does Being Rich/Lean Affect Your Engine?
 

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Discussion Starter #33
That's kind of what I've been assuming based on what I've read. Your stated 14.8-15.1 AFR's for light cruise is completely normal and correct, though 14.1 idle is pretty rich. Obviously you're not getting the most accurate info by using Torque, though it's better than nothing. Your AFR's after fitting the RBE are obviously all wrong, both too rich in idle/cruise and too lean during WOT.

Obviously it's not hard to pull lambda numbers off the internet but enrichment past MBT (or at least MRT) is a waste and is just going to be lost power/economy. Also, 1 lambda is not 14.7:1 for any fuel other than E0, which is becoming increasingly difficult to find these days. I hate having to bring that up but most people that try and correlate 1 lambda to 14.7:1 AFR just don't actually understand how lambda correlates to the stoichiometric value of a given fuel. Seems how stoich of E85 is 9.8:1, the exact same .85 lambda command would enrich it to 8.3:1 when compared to the E0's 12.5:1.

Anyways, I suspect a lot of the information related to Duke AFR's is probably just not the most accurate here. What options are there for datalogging? Are there any?

Can you please explain why "Obviously you're not getting the most accurate info by using Torque". The way I understand it the torque app just shows the information which the KTM ECU provides. So basically you are saying the KTM ECU shows incorrect values. Why?
 

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Can you please explain why "Obviously you're not getting the most accurate info by using Torque". The way I understand it the torque app just shows the information which the KTM ECU provides. So basically you are saying the KTM ECU shows incorrect values. Why?
Your assumption of my statement is flawed. Torque just doesn't have the refresh capabilities or accuracy that tuners need, which is why tuners don't use Torque. It's not that it's a bad program, it's just not great for anyone above the novice/shadetree mechanic level.
 

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Discussion Starter #35
Your assumption of my statement is flawed. Torque just doesn't have the refresh capabilities or accuracy that tuners need, which is why tuners don't use Torque. It's not that it's a bad program, it's just not great for anyone above the novice/shadetree mechanic level.
Thanks for the explanation - good to know.
Is there any other program available for a reasonable price with works similar like Torque but is more accurate?
 

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Thanks for the explanation - good to know.
Is there any other program available for a reasonable price with works similar like Torque but is more accurate?
Well, that's basically what I've been asking. I've been tuning my cars during the last four years but never messed with a motorcycle. I would assume that the Power Commander V would be what I'm looking towards but it doesn't seem like there's much info about it here.
 

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To met strict emission standards bikes have to run very lean thus they stutter especially at low rpm and overheat a bit, piggy back ECUs don't care about emissions and provide maps with best values for the bike to run smooth and as best as possible.

KTM could make perfect map for DUke but I bet they wouldn't get an approval for the bike thus couldn't sell it on the market.
which is total crap
 

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Sadly I don't have the WOT AFR's on the stock tune.
During light cruising say 20-40% throttle I was seeing 14.8-15.1 AFR's and a Idle AFR of 14.1
The only modifications I had at the time was a drop in K&N filter, on 91 octane, at sea level.

After fitting the rapid bike easy I was seeing the following:
Idle AFR 13.4
Driving AFR: 13.8-14.0
WOT AFR: 13.8

All of this was utilizing the Bluetooth adapter and torque app to measure AFRs.
Hi, what adapter are you using to bluetooth to the Torque app? I use Torque on automotive 16 pin adapters (ELM 327)
Thanks
 

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what are you all doing with Torque to get AFR? I cannot get my torque app to read AFR?

I know its not accurate, but I'd like to be able to get close and see changes when I tune it.

Has anyone fitted a wideband in place of the stocker? I have done this on cars in the past. Usually there is a wire that you can run to your ECU from the wideband sensor that runs a narrowband signal. You can read your actual AFR with the gauge and your ECU still reads correctly.
 
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