fuel screw replacement technic

7 replies to this topic
  • btray

Posted June 27, 2008 - 05:46 AM


Need to know how to remove stock fuel screw and replace aftermarket screw. I'm at 945' above sealevel and will be riding in 1400-2000' level july 4th. What kind of tool is used to get the old one out and how many turns should the new one be screwed in? If I do the screw all the way in counting the turns will the new one be the same on installation? Does the motor need to be warm in order to adjust the carb for best running and what should I listen for? Can I make a tool to remove the existing screw...I've heard they can be hard to get out if never adjusted or removed before. It is on a 2004 yzf 450. Thanks for your suggestions.

  • krackhead

Posted June 27, 2008 - 07:12 AM


I use a flat head bit off one of those screw drivers where the bit comes off? I am not sure what you call em. Its got the hex shaft, the bit is about an inch long with a flat or phillips head. Anyway I use that to unscrew the stock fuel screw and then make sure you get the small washer and oring that sometimes doesnt fall out, then stick in the new adjustable fuel screw and screw it in all the way, then back it out, typically 2 to 2.5 turns out and you should be good to go

  • matt4x4

Posted June 27, 2008 - 09:38 AM


Before Unscrewing the old one, screw it in until lightly seated - counting the number of turns, then after installing the new one as stated bu Krackhead, seat the new one lightly and turn it out the same turns you counted before - that way you will be at the same setting as before the change which should work fine for your current conditions.

  • btray

Posted June 27, 2008 - 10:11 AM


can you normally turn the stock screw with just the hex bit because of room between the carberator and engine case or do you leave the hex socket with it for leverage? Can the carberator be rotated like the old two strokes used to?

Thanks for your replys

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  • jcham33

Posted June 27, 2008 - 10:35 AM


An FCR on a 05 rmz 250 was able to be rotated enough to get a small screwdriver on the stock fuel screw by unhooking the airbox from the carb.

  • matt4x4

Posted June 27, 2008 - 11:11 AM


I've never tried a hex bit, but thinking about my FCR it might be tight...
I just made a fuel screw tool from a nail in about 2 minutes for my wife's bike one day - I took a framing nail, cut it to 1.5 inches, heated the end with my propane torch, pounded it flat, ground it to make a small screwdriver and used it on her bike, the spiral allows for you to get grip. Beats cutting off your small screwdriver and having nothing much to hold on to for a handle

  • krackhead

Posted June 27, 2008 - 11:14 AM


on the 04 you can turn it far enough to get the hex bit in there but you wont be able to fit a small screw driver in there. You can use the hex bit to adjust the fuel screw, but it is much easier to do so with an after market adjustable fuel screw. jcham must be bored, the YZ's use Keihn carbs and I highly doubt you are going to want to yank the carb off the airbox at the track or whatever destination you are heading too.

  • grayracer513

Posted June 27, 2008 - 11:29 AM



Handy for changing jets without moving the carb, too.

See this thread for a simple solution to reinstalling a pilot jet with the float bowl on the carb and the carb upright:


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