Hello
I just bought a new yfz450 the dealer installed the GYTR pipe for me, it only has about a 1 to 2 hours on it. I have noticed that it pops alot on deceliration, also last night I noticed the head pipe was glowing red, is this normal? I live in Northern Utah and the elevation is 4200 feet, I will be going to St. Anthony Dunes quite alot and will need it jetted for that elevation. Any help would be greatly appreciated. One more thing I have a K&N filter but I have not installed it yet because I think I am already to lean.

 

I don't know anything about jetting on a yfz, but I have heard these guys talking about the red pipe, it is normal.

 

the red pipe is sometimes the timing.

 

Did the dealer rejet for you when they installed the pipe? If so, do you know the jet sizes and did they jet it knowing you were going to install a K&N?
If you have the airbox lid on, take it off and run it up the street and see if the deceleration pop decreases. If it decreases, you're running rich. If you are running rich, just put the K&N on and it should take care of the problem.
If you are lean you will need to increase your jet sizes, but I'm not sure which ones would be good for your elevation.

 

I was told that I would not need to rejet because of our elevation. I think the dealer is full of crap.

 

You can't always trust what the dealers say, some of those guys have no clue what they are doing.
Give the air lid test a try, at least you will be able to tell if you're lean or rich.
BTW, don't worry about the glowing head pipe. All YFZ's do that at first.