I have 2012 KTM Duke 125 at 10 000 miles (16k kilometers). I am the third owner of bike for 2 years. Whenever i twist the throttle fastly, motorcycle is chocked up. So i thought the problem could be in spark plug since i assume it has never changed.

I searched eBay and found there are 2 proper spark plugs that i can buy. One of them is copper and looks like secure option. Other one is Laser Iridium Spark Plug which looks like hi-tech.

I have also bought K&N air filter, so that mixture should have more air.

My Question is which one should i go? Please tell me which is safier or more performance?

Thanks. Emre

  • 1
    Are you sure that the spark plugs are to blame? There could be many other causes for your lack of performance...
    – Zaid
    Nov 18, 2015 at 18:21
  • I am confused. Why did you mention about the air filter? Are you asking if you should rather replace the air filter or the spark plugs? I answered below assuming you want to know what type of spark plug is better.
    – rana
    Nov 18, 2015 at 19:55
  • Nope i am not sure, since its easy to check, it is the first one to check. Nov 20, 2015 at 8:24
  • I mentioned the air filter because it effects mixture. So i may need stronger or weaker spark plug to burn mixture properly. Nov 20, 2015 at 8:25

3 Answers 3


First of all blaming your chocking problem fully on the spark plug is not wise there could be tons of other factors which can cause the chocking issue on your bike for example.

  • Bad air filter.
  • Bad fuel pump.
  • Bad fuel itself.
  • Fault with the ECU.

Check all of the above components before coming to the conclusion of changing spark plugs.

Also spark plugs usually last longer than 16k Kms.

secondly the NGK iridium spark plugs have nothing to do with performance of you vehicle, they simply last longer than the copper tipped counterparts, there is no proper reason to go for the iridium ones if you only want performance.

I would simply suggest checking out the above components and if the spark plug indeed is broken and you need to change them its up to you , the iridium last longer that's about it.


Iridium spark plugs are not going to give you more performance compared to copper types. You will notice increased performance only if the current plugs are in bad shape to begin with. The advantage of iridium spark plug is that they last a lot longer compared to the copper ones. So you don't have to change plugs that often.

So it is up to you to decide if you want to spend the extra money now or to change spark plugs more often.

On a side note: Spark plugs in cars last a lot longer than 16k Kms. Usually about 30k Kms even for copper ones. I don't know much about bikes, but you might have a different issue with your bike not related to spark plugs.


sorry jump in a little late, but this might help someone if she is looking for same information.

From my experience, since I changed to NGK Iridium tipped one, my duke390 2014 with running of 37000kms heats a little less. Bike revs a bit smoother in lower gears now. Previous copper one wasn't bad as I change them every 10000kms. Just to make it clear, I only changed spark plug(and not do any other maintenance at that time) and observed these changes. I don't have proper data as to how much heat has been reduced or how smooth bike runs now, but when I ride another duke390 of same year from a friend, I feel the difference.

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