Hey Nikroc
I put back the same type of spark plug because I reckon the soot is the result of whatever is misbehaving, not the spark plug having a wrong heat range. Will be difficult to run injector cleaner through the system if the engine can't run. Or do I power the pump and injector separately and just drain into a bucket? Got a tip from a bike technician to run the fuel pump at reverse polarity in a bath of petrol, to flush out any crud that may have accumulated inside the pump.
Yes, I can buy on E-Bay...