Need some help

[kookennay]

i am helping out a friend of mine who has an 04 450, and i am not real familiar with these. My problem is when you hit the the throttle real fastit like stumbles and sometimes just stops running. It is stock except for a mega bomb head pipe and powercore 4. I was told it had been jetted, but my friend says when it idles when its dark you can see the pipe turning red. i would say its lean. Any help will be greatly appreciated! Thanks

[Colby@C&DRacing]

it will glow to the bend on the headpipe off the motor but if it is further back than that sounds like it may need rejeted. Sounds like you might need to change the leak jet as well.

[kookennay]

i have heard that its better to just close off the leak jet? does an 04 even have a leak jet?

[XcYFZRacer]

You need to get a 50 leak jet for it. Wire tie the accelerator pump arm back (search zip tie mod). that will give you a good starting point.

[kookennay]

OK THANKS GUYS I WILL START THERE. IT WOM'T LET ME SEARCH ZIP TIE MOD EITHER.

[Vampire2800]

Here, courtesy of Google & youTube

http://www.google.com/m/search?q=yfz450+zip+tie+mod&mshr=29&popt=1&pbx=1&aq=0&oq=Yfz450+zip+t&aqi=&fkt=2567&fsdt=13345&csll=&action=&ltoken=03198615