[02crfrider]

I just bought my first 450 its a 02crf 450 it has a fmf slip on on it and what appears no air box lid but when I started it the head pipe turns red and is backfiring when u let off and doesn't want to idle... any help would be greatly apprieciated[/quote]

[crfsonly]

welcome to CRF's Only and congrats on your new ride. get the JD jetting kit and an adjustable fuel screw:

http://www.crfsonly.com/catalog/product ... ts_id/1094

http://www.crfsonly.com/catalog/product ... ts_id/1333

both will get your jetting spot on.

again, welcome.

Ken

[saefabri]

I ordered the JD kit and fuel screw. Expect them to arrive within few days. I don't have the instructions yet but I guess I could do the jetting myself without surprises.
is it possible to access needle jet without taking the carb out?

[crfsonly]

yes...you will be able to install it without removing the carb. here's a how-to link:

http://crfsonly.com/howto/450x/jetting/ ... needle.php

ken

[02crfrider]

I have now added a head pipe but i was hoping for a size to start out figuring from.. Any help is appreciated