pilot jet

3 replies to this topic
  • Mark_UK

Posted August 02, 2002 - 01:38 PM


ok,,,i have a 98 yz just reduced the squirt from 3 seconds to <.5 seconds
now it pops and bangs when i shut the throttle off.
i assume this is the result of the pilot jet being to weak?
ive turned the fuel screw out a full turn and it now sits at about 2 1/4 turns out.
so my question is
where on the carb will i find the pilot jet?
how much of a jump should i make in jet size.?
also should i raise the needle at all?

the bike runs hot at low revs [ again i assume this is a pilot jet issue?]

also does anyone have a diagram or can they explain which jets are where ?
i know its a dumb question but i guess its the only way ill learn

thanks in advance

  • skthom2320

Posted August 02, 2002 - 01:44 PM


Do a search for "jetting 101" on the YZ250F board. It is an excellent write up on jetting these bikes.

The pilot jet is under the float bowl. Take the screw out of the float bowl to access. The pilot requires a flat blade screwdriver. The main is a hex head. You will see them both. A snap to change. Sounds like you need to go at least one larger on the pilot.

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  • Old_Novice

Posted August 02, 2002 - 02:01 PM


The pilot jet is in the float bowl area to the left of the main jet if you are looking at the carb from the rear. You can't actually see it like the main jet as it is up in a sort of passage.

  • tk421

Posted August 02, 2002 - 02:19 PM


It's number 20 on this diagram.


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