yeah i bought a yfz450 its pretty nice but the dealer said that it will take at least 3 tanks of gas to break in the high performance motor. i was breaking it in and it was at night and the pipe was red hot almost a cherry color i have no idea whats going on there but id like to know if any of you guys have any experience witht he 450 motor and how hot it ran none of the temp lights came on or no loss of power was noticed this is my first 4 stroke so any help would be greatful i just havent seen a pipe get that hot before and maybe its just for the break in but i hope it doesnt do this all the time or maybe its running lean but could u guys witht he 450 bike motor please help or if anybody knows anything thanks

 

Trencher...
i dont know much on a 450 motor but i have a 250ex it has a 4 stroke engine and mine does that only when i running it hard when i am racing with my friends maybe that helps

 

The header was red hot or the muffler on the rear end was red hot. where you just letting the bike idle or where you riding to break it in. If you where just letting it idle the exhaust piping wouldnt have air going by it to help it cool down. I have put 75 miles on my YFZ and the header has changed to a darker purple color. it was never glowing red, I was riding in temps of 85-95. hope this helps dave

 

We were out test riding my friends new YFZ450 they day he got it. It was dark outside. And when he came back from just riding it around mildly for a couple minutes, They pipe was glowing so bad, i thought it was going to melt. But I guess everything is ok. Sounds like thats what they all do.

 

Its because the header is made out of stainless steel. My two brothers racing stainless headers on my street bike do the same, then on cool down, they turn kind of a purple-ish color. I think it is perfectly normal. You just don't see that kind of a thing on normal black painted stock steel exhaust headers. I wouldnt worry about it! Have fun riding, I am extremely jealious, mine hasnt come in yet.

 

Rappy does the same thing, it's normal I wouldnt worry bout it. If it really bothers you then take it to the dealership and ask them, if it's a prob then warranty will fix it.

 

You might think of checking your valves. I have only seen headers glow like that once. It was on a Raptor and when the guy checked his valves, the exhausts were way out of specs. Just a thought. Happy riding

~HoundDog

 

I've noticed this before on my yfz, but I never stopped to think if anything is wrong with it, haha
I just take turns ridin my KFX700 and YFZ450

 

Hey, how about telling us how the two of yours compare?/ pros / cons of each?

 

The 400ex does the same thing after installing a slip-on. We were told to try putting the stock back on, and it still did it. I just think we didn't notice it. There hasn't been any problems with it, so I don't think I would worry about it.