glowing head pipe on my 250F

[Yzed-250F]

I ride and race a well maintained YZ-250F. At the last Valley Motosports Friday night race (Fondulac), while on the starting line warming up the bike, I noticed my head pipe was glowing red. In addition to just finishing a race, I warmed it up probably two minutes longer than usual due to delays on the gate. I have never noticed this before. The only difference weather wise was about 15 degrees warmer than the other races. Never-the-less, the bike still ran great all night...as usual, I checked the plug before the race and it looked perfect. I have not checked it afterwards yet. Jetting is stock, I've tweaked the air screws and it runs great.

Could this simply be a result of the combination of the warmer weather and excessive warm up time?

 

[Danny8785]

Most fourstrokes will do that if left to warm up with the choke on. I have seen many XR's do that warming up without the choke! I would think that Your high compresion high preformance MX fourstroke would do that even worse than an XR. I dont think you should worry about it, but then again i dont know for sure. Dont just go on my opinon.

 

[Rich Rohrich]

It's normal when you let it sit and idle for too long. No worries.