I have a 2003 wr 450 that I have taken to different mechanics here in San Diego and nobody can figure out what is wrong. The bike runs perfect for the first few miles then being at full throttle for more than a few seconds causes the bike to bog, once you let off the throttle it runs fine as long as you dont go back to full throttle. The more you go to full throttle the worse the bogging gets eventually it starts happening at 3/4 throttle then 1/2 throttle and so on. The bike then starts to backfires and will die, and then will not run more than 1 foot without stalling. Then it gets wierd. Let the bike sit for a few hours and its magically back to normal and then it starts all over again. Both myself and mechanics have cleaned the carb. I checked the fuel line and fuel cap vent they were both clear. Anybody have any ideas?