I have an OS 160Fx and it seems to make a pinging or metalic sound when its running around half throttle. Low end idles great and high end is slightly rich. Its a new engine with 4 tanks of gas through it( Cool power 5%). It was broken in as per the manual.
I am wondering if this could be pre-ignition/detonation and if so would a cooler glow plug help? I currently use an OS #8.

Thanks in advance.
Paul