Carburetor adjustments yamaha 450yfz 2004

Turn both the air screw and throttle screw inward until they LIGHTLY seat. Now back each one outward one and one half turns. This is the factory setting. I am going to give you a web site where you can download a free PDF factory service manual for a YZ450FR. I believe the model is a bit different but the carbs are the same.

Go to this site and you can download a free PDF service manual. The site may take up to 25 seconds to fully load the list of manuals. It is worth the wait. www.carlsalter.com/motorcycle-manuals.asp The service procedures are there in detail and a lot of diagrams and photos. Don't mess with the pilot screw unless you have to, Part #11 in the diagram.
Can I get a Very Helpful" rating out of this?

Part 11 is the Air mixture screw, 2 1/2 turns is what mine took to run like it should. 45 idle or pilot jet is what I had to change to. The guy I bought he quad from never drained the carb bowl when not in use. If you let that fuel sit in the bowl it will cause issues, the fuel will evaporate and the crud is left behind to plug up the jets and cause issues with the float needle. I drain it if its going to sit more than a week.
Turn your Pet Cock valve off then either start the quad and let it run until it stalls or drain the carb bowl by backing out the Allen screw on the left side of the carb at the bottom of the bowl, fuel will run out so catch it with something ( coffee can).

98 yzf 400 wont idle

More then likely if your having carburator problems its nothing to do with the adjustments. In the past few years i've found the most common problem is that people are using fuel with ETHANOL in it which will cause nothing but problems internally to the fuel system. Ive seen the inside of a carb turn green from ethanol and plug the tiny holes in the pilot jet after only being parked for 2 weeks.

1 half turn, get the bike running, go back until it tries to die, go forward until it tries to die, adjust to the middle of that. Factory.