Yz450f Help!!!

i have a total stock 03 yz450f..i want to do mods such as openeing up the air box..removing stock baffle from exhuast..if i do these mods will i HAVE to re jet my carb? also..is ther any adjustments i can do to the carb to avoid re jetting? any help will be greatly appreciated -josh

Hi Josh,

In a word, yes. Any changes you make that flow more air will need *some* amount of carb adjustment.

Much of the rejetting you'd have to do can be done through the 17mm port on the bottom of the carb or with the fuel screw. They're 15 minute jobs at the most, and very simple after you do them the first time. You can get to the needle by pulling the tank and rotating the carb in the rubber boots - a little more wrenching, but no biggie.

If you use an aftermarket fuel screw, it will save you a bunch of time if you need to adjust your pilot circuit. They're about $20 in the TT store.


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