I have had this 250 for about 8 months. I have used it for deer hunting and ice fishing. I live in northern mn and I keep it garaged. When I do not use it for a couple of weeks, I like to start it and warm it up.
I have to use a vary small squirt of starting fluid to get it going. I use high octene gas with a dash of Sea Foam in the tank. The problem is last night the temps reached into the high 20's and I started it up pulled the choke wide open gave it a shot of ether and fired up. I let it run for about 1 min closed the choke, it ran for about 2 min when I noticed the the exhaust pipe next to the head was turning cherry red. I shut the engine off ASAP. During the warm up I moved the shifter to neutral and did mess with thumb idle screw on the carb to try and smooth it out a bit.

Any ideas why this happened? Maybe it does this all the time I just never noticed it before. Thanks

 

This sounds normal, was it dark where the pipe was? Another possibly is that the air to gas mixture is lean, to check this, just pull the spark plug and see if it is a white-ish color.

 

Ya it was dark. But will check the plug. Thanks