carb adjustment help needed


10 replies to this topic
  • mxracer452

Posted February 27, 2005 - 07:56 PM

#1

I have a 2003 yz450f which i have just put in a new piston and rings and new valve seals. I also raised the needle one position to take care of the popping on deceleration. Now when i start my bike i have to hold in the hotstart lever for it to run...as soon as i let go of it..the bike shuts off...any suggestions would be greatly appreciated....thanks

  • skthom2320

Posted February 27, 2005 - 08:10 PM

#2

Lower the needle one clip and adjust the fuel screw instead (richer = OUT). If you need more than 2.5 turns out (total) on the FS, put in a larger pilot jet.

Did you by chance remove the carb slide and reinstall it upside down?

  • mxracer452

Posted February 27, 2005 - 08:58 PM

#3

thanks i'll try that.....do u know how much to turn the air screw out as well to get the settings just right on it?

  • skthom2320

Posted February 27, 2005 - 09:12 PM

#4

You have to do it by "feel" really. Usually decel popping can be fixed with about 1/2 turn or so out. Depends on how bad it's popping.

So, figure out your current FS setting by counting the number of turns IN until it is lightly seated. Then return it to where it was.

Next, put the needle back to the position you had.

Now ride the bike and get it good and warm. Bring it back in and turn the FS out about 1/4 turn at a time until the decel popping "just" goes away while riding. I actually prefer my bike to have just a small amount of popping here and there - that's where I think you get the snappiest response. If you have to go more than 2.5 turns total, put in the next larger pilot jet.

  • mxracer452

Posted February 28, 2005 - 02:00 PM

#5

thnx for ur help skthom2320 the plate on the carb slide was upside down...runs great now :)

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  • grayracer513

Posted February 28, 2005 - 02:13 PM

#6

No problem, as long as you don't ask skthom2320 how he knew that could be the problem. :)

  • skthom2320

Posted February 28, 2005 - 03:19 PM

#7

No problem, as long as you don't ask skthom2320 how he knew that could be the problem. :p




:) :)

  • stealman

Posted February 28, 2005 - 05:43 PM

#8

Im having trouble getting my bike to run good so I have been reading all posts about carb settings. I was wondering what the plate on the carb slide is and how I can tell if it is upside down or right side up? Thanks.

  • yzf450jack

Posted February 28, 2005 - 06:40 PM

#9

The flat part of the plate is on the bottom it's a common mistake They should put an arrow on it! This side up

  • stealman

Posted February 28, 2005 - 07:06 PM

#10

When you say plate do you mean the plate that you see when looking in side the intake port?

  • mxracer452

Posted February 28, 2005 - 11:39 PM

#11

no...the plate is on the motor side of the carb....when u take the top cover off the carb u should see a gold phillips screw and an allen screw....if u remove the phillips screw and take out the slide the plate is on the motor side....be careful because it will fall off if u dont have a hold of it...and if it's on upside down it won't allow enough air into the motor....just remember the flat side of the plate goes down.....





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