09 Fuel adjustment

2 replies to this topic
  • downin

Posted March 06, 2011 - 02:53 PM


Where is the fuel adjusment screw located at on the carb of the o9 450s and what does the service manual refer to it as?

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  • Mr. Neutron

Posted March 06, 2011 - 03:04 PM


In my manual for my '06, Yamaha calls it a "Pilot Screw". It's probably called the same thing in your '09's manual, I'd guess.....

If you have the stock brass one, with the tiny head, and a slot in it for a regular screwdriver, it's kinda hard to see. Aftermarket fuel screws (or Pilot Screws; whatever.....) typically have a much bigger head on the end extending out from the carb. They're easier to see, and much easier to adjust. They're worth the investment, if you don't have one.....

The fuel screw is just in front of the float bowl. It extends upwards, vertically, into the main carburetor casting. The float bowl actually has a slight vertical groove cast in the front of it, to give clearance for the "Pilot Screw"/fuel screw/whatever ya wanna call it....

It mostly affects low throttle openings, like from idle to 1/8th or so throttle openings...... Hope this helped ya some.....


  • downin

Posted March 06, 2011 - 04:49 PM


Yup it helped alot, thanks!!

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