Carburetor experts please!

6 replies to this topic
  • HondaFourFifty

Posted March 31, 2013 - 12:50 PM


Ok so I bought a 03 YZ450F that wasn't running so I took off the carburetor, cleaned all jets and passage ways. I also noticed I think this carb has the original quickshot and I'm guessing it came with the red pilot screw. I got it to run for a minute or so but ran bad. I researched and found that there is supposed to be a spring and o ring for the pilot screw. I don't remember seeing a o ring and spring? Help please!

  • cereal killer

Posted March 31, 2013 - 01:36 PM


The o-ring and spring might be wedged in the carb still. Use a pick to pull them out.

Failing that, you can get them from your dealer - or they come with some aftermarket adjustable screws if you decide to go that route.

What do you mean by "red pilot screw"? Is it anodized? Stock is brass. Maybe you have an adjustable one already.

  • HondaFourFifty

Posted March 31, 2013 - 01:40 PM


Anodized red with the numbers 1234 on it. Sorry don't know much about this carb. Is it the same as the fuel screw?

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  • HondaFourFifty

Posted March 31, 2013 - 05:46 PM


So I got it running for about 30 seconds and then I started playing with the choke and it died and havent got it started again. Im thinking maybe that it got clogged again?

  • f150jokerstyle

Posted March 31, 2013 - 06:28 PM


Yes the red fuel screw should have a spring and o-ring under it. With out, it will not run well. also the slide has that removable cut away. Make sure you put in on right side up or it will hardly run as well. As far as the slide cut away the way it appears to fit is wrong and the way you would not think it goes is right. Also another hint the hole in it should be closer towards the bottom of the carb.

  • cereal killer

Posted April 01, 2013 - 04:52 AM


I remember someone posted that the o-rings could be purchased at ace hardware too. You will need both the o-ring and the washer. Make sure you have a look for them first in the hole your fuel screw came out of. Odds are, they are still there.

Sounds like an aftermarket fuel screw. How many turns out do you have it set at? The pilot jet will clog easily if your carb or gas tank aren't clean. It is possible it happened again.

  • HondaFourFifty

Posted April 01, 2013 - 07:19 AM


I think its aftermarket. And I think the gas tank is still dirty too. I'll take a look tonight

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