[69birdboy]

I am having a strange detonation problem. I've never had detonation before.

Above about 4000 rpm and at full throttle, I am getting quite a bit of detonation. I haven't changed anything since last summer, and am still using the same premium gas.

I like the way it runs at part throttle, but want to get rid of the detonation at full throttle. What should I do?