2018 ktm 250sx

Just bought a 18, 250sx, runs fine when you are riding it but at idle it detonated and you can here the knocking, dealer said it was running too lean, running motorex at 60:1and vp 110 fuel. it is 45 deg here in ohio currently. what do u guys got yours jetted at 

I doubt you are hearing detonation, especially only when idling.

Detonation is usually only apparent when the engine is under a load.

Maybe mistaken for powervalve, cold piston slap or other engine noises.

Perhaps post a video of it.

 

Inspection of the spark plug would maybe show little metallic specs stuck on the insulator.

 

Check the ignition timing for too much advance.

110 octane requirement is excessive for an otherwise stock engine.

Edited by mlatour
9 hours ago, mlatour said:

I doubt you are hearing detonation, especially only when idling.

Detonationis usually only apparent when the engine is under a load.

Maybe mistaken for powervalve, cold piston slap or other engine noises.

Perhaps post a video of it.

 

Inspection of the spark plug would maybe show little metallic specs stuck on the insulator.

 

Check the ignition timing for too much advance.

110 octane requirement is excessive for an otherwise stock engine.

i took it to the dealer and they heard it and said it was running way to lean and that was “pre detonation” i didn’t have them fix it due to time.  i had to go

Perhaps 'pre-ignition' was mentioned?

That too would be apparent when riding, not just idling.

Dealer didn't want to or didn't know how to 'deal' with your issue.

1 minute ago, mlatour said:

Perhaps 'pre-ignition' was mentioned?

That too would be apparent when riding, not just idling.

Dealer didn't want to or didn't know how to 'deal' with your issue.

 

480A20D4-3868-475A-B76D-1D1286004E6E.jpeg

Just now, upsMan67 said:

 

480A20D4-3868-475A-B76D-1D1286004E6E.jpeg

this is the plug

You mentioned 45°F ambiant temperature,

have you corrected to the service manual's jetting chart suggestions ? 

 

If in doubt, inspect everything fuel and timing related.

A few years back, weren't brand new KTM owners finding little bits of plastic 

stuck in their carburetors clogging the fuel inlet and pilot jet.

 

 

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