Hi, I have a friend that just bought a 03' YZ 250F, And he was wondering: Is the Header pipe suposed to get red hot at the front or not. It is the stock pipe and header, and he was just concerned about it. I was thinking that he should just go and buy a new Pipe and Header Like an FMF or a White Bros. I really need some info on all this, your help is greatly appreciated.
Yes they glow cherry red if you are idling it while sitting still. This week I was getting ready to do some work on my son's and the header was glowing pretty good despite it being about 40 degrees in the garage. I found that just lightly blowing over it cooled it enough to stop the glow.
Even though these thumpers will sit and idle just fine. They don't like it. 4 strokes tend to get very hot doing this. When idleing it is normal for the pipe to get red. I guess a 2 stroke would get just as hot if they would idle.