dendamd

Hello everyone.... I have a 2007 WR250F that I recently acquired....and I have a concern about the stock exhaust. When the bike is started using the fuel enrichner lever, during the warmup, the exhaust header gets RED HOT!!!.....Is this normal????? Once the bike is warmed up enough to ride the pipe cools down and looks normal, but I can't ride it until it warms up enough to stay running which takes about 4-5 minutes of really high idling with the enrichner on. I'm concerned there may be something wrong with the bike...and I don't want to damage the motor due to the high temperatures.......I've had several dirt bikes and quads and have never seen this.....Any info or help would be greatly appreciated....Thanks!