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Discussion Starter #1
my first post :)
I have a 2018 TPI 250 2T KTM and every two or three hours my sparkplug fails...
the bike will not start only when I replace the spark plug.

did anyone encounter this with his/her TPI?
what could be the possible causes
what could be the possible solutions...

thank you very much for the prompt response...
Shak
 

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Welcome to forum. Show us a picture of a plug that has failed please.
 

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Discussion Starter #3
thanks Axzon,
here is a picture of the plug after a clean up. it still failed after a short attempt...

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1582097066582.png
 

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OK... would have been better if you left it like the plug was when it came out from the motor. But it looks quite black. And so I assume that there was some black carbon stuck on it too? As we want the plug to be nicely brown and dry clearly all is not as it should be.

Let's start with these questions to narrow down the possibilities:
  • The carbon you cleaned off the plug, was it soft and oily?
  • Is there excessive smoke when she runs?
  • Does she run nice and crisp?
  • How many hours has the motor run?
  • Has the motor had a new piston? If so, at what hour?
With the TPI there are no jets to change, but from the plug it looks like you have her running rich.
 

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Discussion Starter #5
thanks man for the quick reply...
here are some answers for your question...

  • The carbon you cleaned off the plug, was it soft and oily?
answer: it was mild oily but I needed a brush to take it off..
  • Is there excessive smoke when she runs?
not really only when it is cold, more than other bikes when they are cold
  • Does she run nice and crisp?
yes - most of the time. on my recent ride, it didn't hold idle and was stopping every time I left the gas throttle
  • How many hours has the motor run?
approximately 300 hrs.
  • Has the motor had a new piston? If so, at what hour?
yes, at about 150 hrs

note that the plug is failing after the second ride. so if I change the plug to new one, it will hold for couple of hours. then the next day, it will start and burn after less than a minute...
 

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OK. So at 300 hours it is time for a new piston (as 150 hours/piston seems to be recommendation)? This could help as if the rings are worn you will get more oil to the top shortening the life of the plug.

Regarding your idling problem, it might be partly as a result of worn rings. But Slavens have a modification to help with idling setting. Check this video:
 

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Discussion Starter #7
thanks so much. I'll try it. the video is great and explains a lot.
 

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Sorting the idle by doing what the video explains might also help with the life length of your spark plug. But I doubt it. As you have done 150 hours since latest piston change (on the 125sx we did pistons at 40h and rings at 20 hours) I would still contemplate a new piston. As there is no mechanical damage to the sparkplug the culprit can only be ignition unit, heat or fuel/oil.
I got concerned when one of the videos re the TPI engines discussed the lack of oil/fuel going in to the cylinder as result of how KTM has solved the idling adjustment on these bikes and there was a comment re wear of the bore in the cylinder as result...

- If the dead plug would be caused by the ignition you would not be able to re-use the sparkplug after you had cleaned it. And as the plug is made to create a spark it does not care when the spark comes ruling out any timing issues. Your bike would also not be running well in the 3 hours before the plug stops working.

- The black plug (instead of a nicely brown one) indicates that there is too much oil/fuel coming in. If we assume that the fuel injection is working OK you are only left with piston/rings as the reason. Have you done a compression test?

- Have you noticed that your bike is overheating? Is the water in the radiators boiling? The black plug does not indicate that this would be the cause.
 

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my first post :)
I have a 2018 TPI 250 2T KTM and every two or three hours my sparkplug fails...
the bike will not start only when I replace the spark plug.

did anyone encounter this with his/her TPI?
what could be the possible causes
what could be the possible solutions...

thank you very much for the prompt response...
Shak
- unknown as to the issue - try running a hotter plug iridium's are great plugs
it could be a timing issue so the compression is less when first ignited -
this bike is a efi model take it into the shop and get them to check it -
either tps is off if it has 02 sensor it is off both of these parts affect timing
even the engine temp sensor could be wrong
and maybe your not riding it correctly
 
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