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Discussion Starter · #1 ·
Hey! New girl here. Still learning how to ride a motorcycle (and waiting for exam to get my license), but some technical questions already showed up.
I've just got a beautiful 390 Duke 2013 with 10k mileage. All service and maintenance works have been done by KTM official dealer, at least, according to documents. There were two previous owners, I'm the third one.
So, to keep it short...
  1. Duke kind of pulls, twitches and jerking even on high speed. Previous owner used 98 gasoline instead of 95, could this be the reason? I just filled the tank with 95, hopefully there is no need to change injection or any filters... right?
  2. Gonna change the spark plug to iridium LKAR8A-9. As I understood, people here have done it. Any possible problems could happen?
  3. The kill switch is sensitive way too much. Dealer offered to change it for €120 (wtf!), so I wonder whether there is an option to fix it by myself? This topic has also been mentioned here in forum, but the only solution I saw was the addition of WD40 to the switch contact area. Is it so or are there any other methods?
Thank you so much! :)
 

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Hey! New girl here. Still learning how to ride a motorcycle (and waiting for exam to get my license), but some technical questions already showed up.
I've just got a beautiful 390 Duke 2013 with 10k mileage. All service and maintenance works have been done by KTM official dealer, at least, according to documents. There were two previous owners, I'm the third one.
So, to keep it short...
  1. Duke kind of pulls, twitches and jerking even on high speed. Previous owner used 98 gasoline instead of 95, could this be the reason? I just filled the tank with 95, hopefully there is no need to change injection or any filters... right?
  2. Gonna change the spark plug to iridium LKAR8A-9. As I understood, people here have done it. Any possible problems could happen?
  3. The kill switch is sensitive way too much. Dealer offered to change it for €120 (wtf!), so I wonder whether there is an option to fix it by myself? This topic has also been mentioned here in forum, but the only solution I saw was the addition of WD40 to the switch contact area. Is it so or are there any other methods?
Thank you so much! :)
Welcome to the club!
1. Being jerky is in the nature of this bike to an extend. Especially at lower RPMs. But in your case, it's in higher speeds. It could be of various reasons. You can start with a new spark plug, clean air filter and fuel filter. Also, it would be good to clean the throttle body. Use a fuel injector cleaner as well(you pour it with the fuel).
Once all these are done, do a ECU reset/ re-learning by letting your bike idle for 15 mins without side stand and not touching anything. There are high chances your issue will be resolved.
2. There is nothing wrong in using an iridium work plug. Just make sure that it is of the same length as the OEM spark plug.
3. The switch assembly can be easily opened and cleaned.
 

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It the kill switch has a problem then the bike won't run properly - whatever you do.
You can try to repair it or get a new one or a used one.
Here you can check the part number: KTM.SparePartsFinderFrontend
As far as I see it is number 90111074000 for your bike.
Then google it and check what you get. I found two offers for about 100 GBP.

95 is fine.
If the bike was regular services then it's unlikely that the spark plug is the problem. If you change it then I suggest use what KTM recommends for your bike.
 

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Put wd40 into your kill switch and you will have even more problems, guaranteed.
of course you can change the switch yourself, this is a small motorcycle, not a rocket, so no need to be a rocket scientist to fix it yourself.
higher octane rating in the fuel Hurts nothing! All owners manuals for bikes/autos will give a MINIMUM octane rating for sufficient operation ( in order to prevent pre-ignition) and a higher rating does no harm. often the engine will be even happier, at an increased operating expense.
 

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First and foremost learn to ride your Duke.

Higher octane fuel (gasoline) in general burns cleaner due to additives not present in lower octane fuels.
When the previous owner used 98 octane petrol it is very unlikely you will need to clean the throttle body or injector.
The remark from Sasin Syam on the spark plug can cause disaster to your bike. Nothing wrong with a Laser Iridium plug BUT this MUST be the correct heat range, from NGK this is the LKAR8AI-9 not just any plug with the same thread length. (the LKAR8A-9 you mentioned is not an iridium version but the copper variant and good to use as well).
If the kill switch is giving you problems but when on "run" it works fine, I would not use the switch and perhaps just tape it in the ON position and only use the ignition key (I am doing this anyway, never use the kill switch).
 

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If the kill switch is giving you problems but when on "run" it works fine, I would not use the switch and perhaps just tape it in the ON position and only use the ignition key (I am doing this anyway, never use the kill switch).
The kill switch should work, even if you don't use it under normal conditions.
In an emergency it should work!
 

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Discussion Starter · #7 ·
Welcome to the club!
1. Being jerky is in the nature of this bike to an extend. Especially at lower RPMs. But in your case, it's in higher speeds. It could be of various reasons. You can start with a new spark plug, clean air filter and fuel filter. Also, it would be good to clean the throttle body. Use a fuel injector cleaner as well(you pour it with the fuel).
Once all these are done, do a ECU reset/ re-learning by letting your bike idle for 15 mins without side stand and not touching anything. There are high chances your issue will be resolved.
2. There is nothing wrong in using an iridium work plug. Just make sure that it is of the same length as the OEM spark plug.
3. The switch assembly can be easily opened and cleaned.
Thank you!
New spark plug will be installed today. I was also thinking about throttle body cleaning, I'm glad that you mentioned it -- at least it worth trying out. Thanks for pointing out the air/fuel filters -- will check them too.
Didn't know about ECU reset -- seems to be a great thing, like the reset for car gearbox.
Thank you once again for help!
 

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Discussion Starter · #8 ·
It the kill switch has a problem then the bike won't run properly - whatever you do.
You can try to repair it or get a new one or a used one.
Here you can check the part number: KTM.SparePartsFinderFrontend
As far as I see it is number 90111074000 for your bike.
Then google it and check what you get. I found two offers for about 100 GBP.

95 is fine.
If the bike was regular services then it's unlikely that the spark plug is the problem. If you change it then I suggest use what KTM recommends for your bike.
Thanks! I will try cleaning the kill switch as a start. If this doesn't help, then KTM service is my best friend :)
 

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Discussion Starter · #9 ·
Put wd40 into your kill switch and you will have even more problems, guaranteed.
of course you can change the switch yourself, this is a small motorcycle, not a rocket, so no need to be a rocket scientist to fix it yourself.
higher octane rating in the fuel Hurts nothing! All owners manuals for bikes/autos will give a MINIMUM octane rating for sufficient operation ( in order to prevent pre-ignition) and a higher rating does no harm. often the engine will be even happier, at an increased operating expense.
Thanks! Why WD40 would bring more problems?
 

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Discussion Starter · #10 ·
First and foremost learn to ride your Duke.

Higher octane fuel (gasoline) in general burns cleaner due to additives not present in lower octane fuels.
When the previous owner used 98 octane petrol it is very unlikely you will need to clean the throttle body or injector.
The remark from Sasin Syam on the spark plug can cause disaster to your bike. Nothing wrong with a Laser Iridium plug BUT this MUST be the correct heat range, from NGK this is the LKAR8AI-9 not just any plug with the same thread length. (the LKAR8A-9 you mentioned is not an iridium version but the copper variant and good to use as well).
If the kill switch is giving you problems but when on "run" it works fine, I would not use the switch and perhaps just tape it in the ON position and only use the ignition key (I am doing this anyway, never use the kill switch).
Thank you! Learning to ride Duke everyday :) It's my first ever bike.
I bought the LKAR8AI-9 from NGK yesterday, hopefully, this is the correct plug. Will install it today.
Kill switch had turned off the bike while riding -- this was rally scary. I was going on a bumpy road and then suddenly... the silence. I'm 100% sure that the button was untouched, so maybe vibration did the bad thing. Anyway, I will clean it and if this doesn't help, then visit KTM service.
 

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Caterine,
If the engine cuts on a (very) bumpy road it could be the side stand switch.
This switch will cut the engine (when in gear) but mostly will come back on straight away.
When riding a (very) bumpy road, the side stand can be pushed down against the retaining spring cutting the engine briefly.
Have fun learning the Duke.


Thank you! Learning to ride Duke everyday :) It's my first ever bike.
I bought the LKAR8AI-9 from NGK yesterday, hopefully, this is the correct plug. Will install it today.
Kill switch had turned off the bike while riding -- this was rally scary. I was going on a bumpy road and then suddenly... the silence. I'm 100% sure that the button was untouched, so maybe vibration did the bad thing. Anyway, I will clean it and if this doesn't help, then visit KTM service.
 

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i had the jerky throttle problems at low rpms.step by step the problem is solved.so i recommend you to the same :)
1- changed spark plug to ngk lkar8a9 non iridyum
2- new air filter
3- new fuel filter
4- new front and rear sprockets and new chain
now everything is smooth
also changed other parts like fork oil and seals but it wont do throttle response better xD
 

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Discussion Starter · #14 ·
i had the jerky throttle problems at low rpms.step by step the problem is solved.so i recommend you to the same :)
1- changed spark plug to ngk lkar8a9 non iridyum
2- new air filter
3- new fuel filter
4- new front and rear sprockets and new chain
now everything is smooth
also changed other parts like fork oil and seals but it wont do throttle response better xD
Thank you! Why did you choose non-iridium spark plug?
 

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Welcome from Kennesaw GA!

It seems like you've gotten good answers to your questions already. I just wanted to welcome you.
 
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First and foremost learn to ride your Duke.

Higher octane fuel (gasoline) in general burns cleaner due to additives not present in lower octane fuels.
When the previous owner used 98 octane petrol it is very unlikely you will need to clean the throttle body or injector.
The remark from Sasin Syam on the spark plug can cause disaster to your bike. Nothing wrong with a Laser Iridium plug BUT this MUST be the correct heat range, from NGK this is the LKAR8AI-9 not just any plug with the same thread length. (the LKAR8A-9 you mentioned is not an iridium version but the copper variant and good to use as well).
If the kill switch is giving you problems but when on "run" it works fine, I would not use the switch and perhaps just tape it in the ON position and only use the ignition key (I am doing this anyway, never use the kill switch).
The throttle body gets dirty regardless of the fuel used. It gets clogged from dust which escapes the air filter. :rolleyes:
The heat range of LKAR8A-9 is 8 while the heat range of the stock Bosch VR5NEU is 5. But these numbers differ for different manufacturers. Please refer to the below chart.
I was answering to the spark plug in context and didn't mean to install anything that fits.
Also, the spark plug gap also matters, The NGK plug in question comes with a 0.9 mm gap while the 390 service manual says it should be 0.8 mm for 2013 390.
53303
 

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Catarina,

Whatever you do never change the gap on the iridium plug, leave it as it comes out of its box.
 

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Discussion Starter · #19 ·
The throttle body gets dirty regardless of the fuel used. It gets clogged from dust which escapes the air filter. :rolleyes:
The heat range of LKAR8A-9 is 8 while the heat range of the stock Bosch VR5NEU is 5. But these numbers differ for different manufacturers. Please refer to the below chart.
I was answering to the spark plug in context and didn't mean to install anything that fits.
Also, the spark plug gap also matters, The NGK plug in question comes with a 0.9 mm gap while the 390 service manual says it should be 0.8 mm for 2013 390.
View attachment 53303
Thank you!!
 

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Discussion Starter · #20 ·
Catarina,

Whatever you do never change the gap on the iridium plug, leave it as it comes out of its box.
I tried to change it by myself, but failed -- could not get the original spark out :oops:
So, at the moment my Duke is in official KTM service, hopefully they manage to do all necessary work correctly.
 
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