This is my first time to ask a question. I hope it is right. I have a 2000 xr400 that is difficult to start. Isn't the engine supposed to fast idle with the choke on. All my old xrs would fast idle. This one just barely idles. Any touch of the throttle will kill it. The dealer told me there was a idle enrichment valve, but I can't find it. The carb has a 132 main jet and a 52 pilot. My riding altitude is usually 7000 to 11000 ft. Thanks for any advice!