I am getting ready to break-in my new engine. I have been told for all intensive purposes that it is a GO .21 5-port.
http://www.casterracingusa.com/produ...8&cat=0&page=1

My concern is the head shims. It came with two brass shims installed, but no additional shims in the box. Some have said that they have three brass and one silver shim.
I use TQ 30% fuel (same as I use in my Novarossi 21BF).
Do I need additional shims?