Hi, im relatively new to the dirt bike scene, i have been riding for about a year now. I have a 2000 WR400 i have found it to be an extremely tempermental bike. it will start from cold nine times out or ten, but when the engine is hot it seems to be a different story. i've had the valve clearances checked and altered by yamaha, and they showed me the correct way to start it in terms of the decompression lever. a friend suggested playing with the 'butterfly', i think that the thing that adjusts the revs?? just wondered if anyone had any suggestions or tips. would be much appreciated.