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2004 YZ250F Jetting

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I have a 2004 YZ250f And I can not get it jetted. The bike has a bog in the mid rang. I have adjusted the needle the main and the pilot nad nothing seams to fix it. I was thinking about changing the leak jet. Will that help?

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It depends on what you do to make it bog. Does just steadily accelerating up through the power band make it bog? Or does it happen when you twist the throttle to WOT? If so, what throttle position are you starting in? How does it act at low throttle?

Be a little more specific about what you're doing that makes it bog.

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It does it mid throttle on a hill. Usualy it dosent do anything untill you try to speed up. But if you give it any gas on a hill it will do bog out. Thank you.

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178 main stock needle 4 from top pilot 40. Floats are good.

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If you're lugging the bike down too much, the issue may be just to shift down. Try 1 step bigger main jet and make sure the low-end jetting isn't overly rich. If the bike isn't running hot or clean enough, the mid-range can stall more easily. A leak jet only affects rapid acceleration and is not likely to help you during a steady mid to full throttle climb.

James

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Which way have you gone on the needle? Stock needle? Since you're in New Mexico I'm assuming fairly high elevation?

The one thing I've learned jetting-wise about this bike is that it's very sensitive to clip position. One slot change can make a huge difference in performance. I've monkeyed around with pilots and mains and they don't seem to affect things that much but clip position is critical.

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I also have a 2004 yzf250 and have posted alot with this same problem and got plenty replys but I still have the bog in the 1st 1/4 throttle and have just learned to live with it which has costs me many races. I have a power now, fmf pc4 slip on, fuel screw 2turns out, 180mj, 45pj, clip at 3rd or 4th position. I did try the Iridium plug which did help some. It would be nice to get rid of the BOG for good.

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jmdishongh,

Your idle mixture (pilot/fuel screw) looks richer than needed and the Power-Now could use a smaller main jet. Try leaning the jetting on both ends and see if clip position #4 starts to work better.

Hope this helps,

James

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