I recently replaced my 2003 WR cam with a YZ cam, the bike is a pig to start now when cold. It seems to rich as the throttle has to be held open a little or it just will not start. It fires but won`t pick up revs to an idle speed. The engine also bogs when the throttle is cracked wide open, WR`s do this but it is much more noticeable now with the YZ cam. Other mods, ported head, full exhaust, opened up air box and twin air filter. I have been reading about the air cut valve mod as I already have changed the jetting to YZ specs. The Australian models show the "Grey" wire so i am also going to try cutting it.