Sparkplug breaks

[Lokheim]

Hello , 

My English is not perfect so sorry for that. Recently I have bought KTM SX 125 2006 and sparkplug keeps breaking (like seen in the video). I don't know what's the problem , I have never seen something like this before. I discovered that coolant was leaking because of one of 6 bolts on top of the head , the thread is broken(it's not loose but not tight enough) , but others bolts are in good shape. Air screw mixture is 1.5 turns out as KTM owners manual recommends. Thanks for your tips , advices.

 

Lokheim.

 

MEGA LINK VIDEO

[Mississippi Bullfrog]

That plug looks rusty to me. If that's from water getting into the cylinder then I wonder if that's damage caused by a hydraulic lock in the cylinder?

 

I think you need to fix that loose bolt before doing anything else.

[Stu]

1 hour ago, Lokheim said:

Hello , 

My English is not perfect so sorry for that.

 

Don't be sorry! your English is better than my Slovakian! 

 

First thing I would be doing is repair the broken bolt and replace the plug and the head gasket too 

[fastbob]

I have never seen anything like that either and I cannot even offer a theory about how that could happen . Once maybe, but you are saying that this has happened repeatedly . There are no forces that I can visualize that would do this except maybe something being done wrong when the plugs are being fitted . 

Edited November 12, 2021 by fastbob

[Bianco2564]

Are the plugs genuine or some sub standard fake?

[billy sugger]

As @Mississippi Bullfrog says, hydraulic lock is powerful enough to do that to a plug. It can actually strip the threads out the head as well. Strip the top end down, get the threads helicoiled on all the bolts, not just the buggered one, and fit a new head gasket