had my first race on my new(to me) 04 450. bike was running great, apart from a blutal cultch, and a very poor suspension setup of which i spent most of the day getting dialed in. Anyway after my second last race, a mate came over and told me he had seen some puffs of white smoke coming from my exhaust on the last lap (he was directly behind). having just pulled into the paddock i took a quick look at the engine, and it seems i have blowen some kinda frost plug, or bung out of the top right on the cyclinder head(see pic). which aslo resulted in a oil leak. am not sure what this part is/does?? or what would have caused this to happen? was it me? or has something failed internaly? i am racing supermoto, and the engine was getting a hard time, it hit the limiter a few times. i did not start the bike again, and seening how i had planned on giving the top end an over haul after the first 3 races anyway, i guess i would best to get it done now, aswell as sort this problem. Thank god i brought the old donkey aswell (yz400) she ran a dream, and i actually got my fasted lap on it, but i guess that must have been down to me already having the suspension sorted, cause it felted very under powered down the straights compared to the 450.