I have an '04 CRF250R that I bought a few years ago. I am doing some head work and I know the head is not stock (got the stock head as a spare with the bike). How do you tell what year the head is by the markings on the intake side of the head? Looking at the intake from the carb in the upper left it is stamped H134, there is KRN cast into the head, and it looks like handwritten on the right side is 07 with 108 underneath. Does anyone have the secret code?