I'm thinking it's just real tight, Ive heard new Evolutions make a racket at first till they get warm. You want to get this engine up to speed and load quickly, prolonged low speed could hurt it's potential. Even better if you can bring the piston to bottom stroke than heat the head with a heat gun or intelligent use of a propane torch just before start. It could make that sound the next 6 starts or so. Make sure the fuel has some castor as part of it's oil package.

I've heard of some guys in cold parts of the country put a 3/8" wide band of aluminum duct tape around the head till the weather gets warmer.