Engine blown up
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The hole isn’t caused by heat ‘as such’
, it’s caused by ‘knocking’ or pre-detonation. It can be caused by over advancing the ignition or having a hot spot that glows hot enough to pre ignite the fuel/air mix.
I’m your case (IMO) it was caused by a cold plug that carried too much heat away from the spark plug element, causing it to foul with ash. The ash led to a glowing hot spot which caused knocking, which caused pressure waves and ate a hole in your piston. I’d rebuild and fit a standard plug. Check it very often during running in and alter as needed.Do some googling on plug temps and ‘plug ate hole in piston’. There’s some really interesting stuff out there that I never knew about...
The engine could well still be running lean aswell. But if lean was the only cause you'd normally get a 4 point heat seizure of the piston before it melted the piston in a 2 stroke atleast. Like what's been said
High compression
Lean mixture
Low ron fuel
Wrong heat rating plug
Carbon build up
Too advanced ignition timing
can all cause detonation.
Your engine failure could be down to any number of the above causes. -
Yeah, I did think it could be lean as well. One things usually exasperated by another. I just thought it best to start with a known ‘symptom’ and taking it from there. All you can really do is rebuild and keep a good eye on the plug for other symptoms. The only way I know to check for air leaks needs the engine to be running. Carefully spray suspect areas with carb cleaner and see if the revs settle down/alter...
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Yeah, I did think it could be lean as well. One things usually exasperated by another. I just thought it best to start with a known ‘symptom’ and taking it from there. All you can really do is rebuild and keep a good eye on the plug for other symptoms. The only way I know to check for air leaks needs the engine to be running. Carefully spray suspect areas with carb cleaner and see if the revs settle down/alter...