adam or bb from m?

i have this derbi mulhacen with the 4 stoke piaggio motor and i have a persistent fault doin my head in, bike starts up and runs ok, but when it gets warm, almost to an exact temperature, bang it knocks the spark off, leave it for a few minutes and its back again, new stator replaced different coil, different cdi / ecu temp sensor for the rad fan is working, bypassed the stand kill switch, still yet i have the same fault, in my eyes it would have been the ecu/cdi, but i have changed this wfor a working model, and same fault, it has a digital clock, but its a p c b and nothing really to check, have you ever had this with a loom, its a good possibility but i dont fancy stripping the loom down fookin italian electrics give you about 2mm of slack