[Joey]

I have an 07 yzf450, pipe gets red hot and when its cold it backfires until its warmed up, sometimes have to run 1/4 choke, any ideas how to fix it?

 

[Joey]

when i go to give it throttle it backfires, but run on 1/4 choke it runs decent then when warmed up its fine

 

[high octane junkie]

sounds about right to me.. it's cold up there in maine!

 

[yamaha 2006]

sounds like your running lean what do you have for jets in your carb?

 

[seebeer]

normal... Mine is cold blooded also, let it warm up then go nuts.

 

[Joenday]

So the red pipe and backfire is normal after pipe and jet.

 

[nagel]

Backfire sounds lean. Does it do it on deceleration too with no throttle? If its only on startup, I'm not sure, but if its also on deceleration, you are lean.

Red header pipe is totally normal on a YFZ. God I can't tell you how many pairs of riding pants that pipe has destroyed for me..

 

[jsanders347]

my buddies yfz did this until he went up a size on the pilot. apparently the carbs on yfz's (fcr's i think) are really touchy.. we got it dialed in though. jetting is trial and error