How fresh is the engine? Is it still close to its break in? It sounds to me like diesel knock. That's indicative of high cylinder pressure. Piston slap. Engines with really high cylinder pressure like that one has, will usually exhibit a diesel like knock mostly when cold, but it gets a little quieter as the engine warms. Usually, it's most audible JUST above idle, with the throttle barely cracked. If that's what it turns out to be, ride on brother. It's normal.
