pilot screw?

2 replies to this topic
  • jermy01

Posted October 08, 2005 - 08:31 PM


hey guys. just got a 2000 yz426. Love it so far. Last weekend i went riding in the mtns (4000 ft) and it was hard to start when hot. it was pretty hot up there.....90's maybe. we had to bump start it most of the time. this weekend down in the local river bed (sealevel) and about 75 outside, no problems starting any time except after i dumped it. it still only took me about 10 kicks tho. is screwing the pilot screw in gonna help me when its hot outside? is the pilot screw located on the exterior of the carb? thanks for ur help in advance.

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  • grayracer513

Posted October 08, 2005 - 09:46 PM


Yes, turning the pilot fuel screw in makes the mixture leaner, which is the correct response to an increase in either altitude or temperature, either of which make the engine richer.

And yes, it's on the outside, sort of. It's located in a small bore forward of the main jet plug in the float bowl. It goes straight up into the carb, and is a straight slotted screw. It's accessible only if you can find a very short-handled, small screwdriver, or tilt the carb a bit. For that reason, most of us have an aftermarket extended screw that can be easily trimmed by hand.

Adjustment Procedure (I know, it's for a 250, but it's the same)

Zip Ty Fuel Screw (as an example)

  • jermy01

Posted October 09, 2005 - 09:48 AM


thanks for your help, will probably get an extended screw

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