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Discussion Starter #1
This is about my experience with my 2017 Duke 390 bought in Thailand. I am not sure how much this applies to other bikes. I asked at my dealer and they told me I have the latest software installed.
I have my bike just for two weeks now and it has a lot of power. But it seems when driving slow, i.e. 20km/h, the engine is stuttering a little in the RPM range of 2,000 to 4,000 RPM. Also the idle rev with rough 1,800 RPM seems high to me.
I read here some riders use power commander and other devices to make their bikes run better but I am wondering if that shouldn’t be KTMs job. Shouldn’t they be able to make the bike run smooth and optimal for all RPM in all conditions? Why don’t they do that and why are there aftermarket devices to change the maps?
This post is not about getting a few more HP out of the bike with higher refs or something like that. My question is about everyday use by everyday riders. I am sure KTM has the money and resources to make things perfect. Why don’t they do it?


About me: I tuned 2-stoke bike when I was young a long time ago. I know the basics about engines and I know computers and programming but I have no experience with modern vehicle electronics.
 

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I feel exactly the same. I don't want more power so would resent spending £150 on something the manufacturer should have fitted.
So why don't ktm make the bikes run smoothly? Is there a disadvantage somewhere?
 

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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.
 

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The jerky shuddering is one of the worst things about this bike. I just try to keep it higher in the Rev range so I can avoid it.
 

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Discussion Starter #5
The jerky shuddering is one of the worst things about this bike. I just try to keep it higher in the Rev range so I can avoid it.
That works. But I would have expected that a 370cc bike engine should be powerful and smooth below 4,000 RPM.
Can anybody confirm if this is all about the ECU?
Or is the camshaft and other parts optimized for higher revs only?


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?
 

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That works. But I would have expected that a 370cc bike engine should be powerful and smooth below 4,000 RPM.
Can anybody confirm if this is all about the ECU?
Or is the camshaft and other parts optimized for higher revs only?


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?
It's a thumper.... Just one cylinder to do so the work. You had gotta expect a bit of the jerking.... It's just this bike has a lot of it!
 

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You'll have to get a twin, triple or four to avoid low rpm jerkiness, as said it's a single, SP370, XT, XR, all did it, it's the mechanical way, to really to avoid it, bolt on a really heavy fly wheel, then it won't accelerate, so there's a compromise, also that little KTM lump pushes out pretty good BHP and tourque and be reliable, so to me, they've done a good job, and one more thing, I know everyone loves modded their bike, but if you want more power, get a bigger bike, my 2 cents
 

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Discussion Starter #8
You'll have to get a twin, triple or four to avoid low rpm jerkiness, as said it's a single, SP370, XT, XR, all did it, it's the mechanical way, to really to avoid it, bolt on a really heavy fly wheel, then it won't accelerate, so there's a compromise, also that little KTM lump pushes out pretty good BHP and tourque and be reliable, so to me, they've done a good job, and one more thing, I know everyone loves modded their bike, but if you want more power, get a bigger bike, my 2 cents
Thanks for your input. I don't want a bigger bike and I don't need more power. I am just asking why it seems aftermarket suppliers are able to make the Duke run smoother than KTM. I think that is a reasonable question.
And it seems the answer might be (see above) that it's about emission laws which KTM has to follow.
I am asking and I am willing to learn, that's the whole idea about a forum.
 

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Duke

This is about my experience with my 2017 Duke 390 bought in Thailand. I am not sure how much this applies to other bikes. I asked at my dealer and they told me I have the latest software installed.
I have my bike just for two weeks now and it has a lot of power. But it seems when driving slow, i.e. 20km/h, the engine is stuttering a little in the RPM range of 2,000 to 4,000 RPM. Also the idle rev with rough 1,800 RPM seems high to me.
I read here some riders use power commander and other devices to make their bikes run better but I am wondering if that shouldn’t be KTMs job. Shouldn’t they be able to make the bike run smooth and optimal for all RPM in all conditions? Why don’t they do that and why are there aftermarket devices to change the maps?
This post is not about getting a few more HP out of the bike with higher refs or something like that. My question is about everyday use by everyday riders. I am sure KTM has the money and resources to make things perfect. Why don’t they do it?


About me: I tuned 2-stoke bike when I was young a long time ago. I know the basics about engines and I know computers and programming but I have no experience with modern vehicle electronics.

Hi Ede...


As has been said many times, these bikes do not drive that well "out of the box"....


Luckily the KTM Main dealer in BKK (The one opp the Harley dealers and Big C) can do a KTM approved re-map for circa 4,000 Baht....


Pictures below show mine being done....


Because more fuel is going in, you will also need to either get the exhause pipe cut open to let the bike "breathe" better - or put a sports can on it - other wise the KTM dealer will be reluctant to do the re-map....


Also (IMHO) - the bike is poorly geared - a good tip is to get a -2 tooth rear sprocket from Tyga performance in Sattahip (4th pic)....


The re-map / mod exhaust and sprocket change massively improved the way the bike drove - all but eliminating the "snatchyness"...


Hope this helps...
.
 

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Discussion Starter #10
Hi Ede...

As has been said many times, these bikes do not drive that well "out of the box"....

Luckily the KTM Main dealer in BKK (The one opp the Harley dealers and Big C) can do a KTM approved re-map for circa 4,000 Baht....

Pictures below show mine being done....

Because more fuel is going in, you will also need to either get the exhause pipe cut open to let the bike "breathe" better - or put a sports can on it - other wise the KTM dealer will be reluctant to do the re-map....

Also (IMHO) - the bike is poorly geared - a good tip is to get a -2 tooth rear sprocket from Tyga performance in Sattahip (4th pic)....

The re-map / mod exhaust and sprocket change massively improved the way the bike drove - all but eliminating the "snatchyness"...

Hope this helps...
.
Yes, this helps!


I think it's a good idea that I wait with this until after the 1,000km inspection.


Does this modified map have a name or is there just one modified map so they know what I am talking about? Maybe I can even mention you if you don't mind (?).
I bought my bike in that shop so I hope they will give me a better price for uploading a map or software. Last time I asked how much they charge and they told me 250THB per hour for a Duke 390 technician. For other bikes it goes up to about 700THB per hour.


Currently I think I will do the exhaust modification with just removing the silencer insert (I am not sure if that is the proper name).
But I have to admit after riding the bike "silent" for the first 300km I get used to a quiet bike.
The "let's rev" instead of using the horn does not really work in the moment. Let's see, I have some more time to make up my mind.
 

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You'll have to get a twin, triple or four to avoid low rpm jerkiness, as said it's a single, SP370, XT, XR, all did it, it's the mechanical way, to really to avoid it, bolt on a really heavy fly wheel, then it won't accelerate, so there's a compromise, also that little KTM lump pushes out pretty good BHP and tourque and be reliable, so to me, they've done a good job, and one more thing, I know everyone loves modded their bike, but if you want more power, get a bigger bike, my 2 cents
Thanks for your input. I don't want a bigger bike and I don't need more power. I am just asking why it seems aftermarket suppliers are able to make the Duke run smoother than KTM. I think that is a reasonable question.
And it seems the answer might be (see above) that it's about emission laws which KTM has to follow.
I am asking and I am willing to learn, that's the whole idea about a forum.
That’s it as far as I’ve learned - emissions control ? I have tried the Rapidbike EASY unit - ok it costs nearly £150 but sorts out the low rpm fuelling issue.

Google it - then ebay it, part number KRBEA-036 it’s a universal fit for ALL duke 390’s.

Happy Riding....
 

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The jerky shuddering is one of the worst things about this bike. I just try to keep it higher in the Rev range so I can avoid it.

Yeah, this is what I do. In car parks I ride the clutch to bring up the revs. Looks a bit silly doing ~10kph and having the bike do 5kRPM but that's the way it goes.
 

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Yes, this helps!


I think it's a good idea that I wait with this until after the 1,000km inspection.


Does this modified map have a name or is there just one modified map so they know what I am talking about? Maybe I can even mention you if you don't mind (?).
I bought my bike in that shop so I hope they will give me a better price for uploading a map or software. Last time I asked how much they charge and they told me 250THB per hour for a Duke 390 technician. For other bikes it goes up to about 700THB per hour.


Currently I think I will do the exhaust modification with just removing the silencer insert (I am not sure if that is the proper name).
But I have to admit after riding the bike "silent" for the first 300km I get used to a quiet bike.
The "let's rev" instead of using the horn does not really work in the moment. Let's see, I have some more time to make up my mind.

i bought my bike there too - and there was no discount for the re-map...


They will know whats what about re-mapping the bike ...


I took my bike to a place that cut the silencer open, cut out a few bits inside which made it breethe and sound better, without getting too much attention from the BIB....


don't waste your time looking at any other re-mapping like rapid bike easy etc - once import durt has been paid, incliding fitting, you'd be looking at 3-4 times the cost of the KTM map - then there would be the voided warranty to boot....


Here's a video of what mine sounded like after the exhaust mod - the cost was 700baht, including a stainless end pipe...




hope this helps...
 

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Discussion Starter #15
Thanks properperson. I looked up your story about your modification. Sounds good. Is the technician who did the exhaust in Bangkok or nearby? If yes then maybe you can let me know some contact information. It's always good when people have the relevant experience.


About the maps: I am 99% sure I will use KTM maps or no other maps at all.
 

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Thanks properperson. I looked up your story about your modification. Sounds good. Is the technician who did the exhaust in Bangkok or nearby? If yes then maybe you can let me know some contact information. It's always good when people have the relevant experience.


About the maps: I am 99% sure I will use KTM maps or no other maps at all.

No, Hua Hin, so prob too far for you - that said there will be loads and loads of suitable places in bkk that can do it - i'd try the KTM dealers first and see if they know a suitable place...........if not try the bike tuning shops - they will either be able to do it, or at least point you in the right direction......
 

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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.
 
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