HELP what should I do my piston detonate!!!!!
 

hey I already add shim 0.1 and engine temp. 105 celsius and still detonate. Any help please!!!!!!!!!!!!!!!

what you should do is give more info......
what engine is it?
what is the total head clearance?
what % fuel are you using?
what plug are you using?
how much fuel through the engine?

what you should do is give more info......
what engine is it? Novarossi .12 L5

what is the total head clearance? Total of 0.4 (0.3 alum. + 0.1 copper)

what % fuel are you using? 25%
what plug are you using? Nova C6tf and C6tc

how much fuel through the engine? In the tank?

try going to a colder plug. what brand fuel?

I will try no.7 plug, fuel mugen 25%