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Jetting a 2005 YZ250F

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I just bought a new 2005 YZ250F and the jetting is off. The header pipe glows red and it backfires on deceleration.

Any advice? The stock pilot is a 42, and the main is a 182.

Thanks! Jeff

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The glowing header pipe is normal. Avoid running the engine while sitting still for long periods.

Backfiring (loud explosions) on deceleration means you're rich on the pilot circuit. Try screwing your fuel screw inwards in 1/4 turn increments.

If, on the other hand, it's "popping" on deceleration, which is more likely given your jetting (unless you've changed the clip positon drastically), then you'll need to adjust the fuel screw outwards in 1/4 turn increments. If you get beyond 3 turns from fully seated, then you'll need to go up one step on your pilot jet. 42 should be fine though.

Edit: Also, make sure there are no air leaks in your intake tract, and that your exhaust header is well-sealed to the cyclinder.

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main is a 182.

Are you sure the main jet is a 182?? You might want to double check that. I beleive it's a 16?.? I am sure some peeps on here know the stock jetting. I switched mine out w/ the JD kit before I even rode it and went up in the main from stock. I am now running a 170 main

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I used to have a #180 main, which was stock, in mine until I got JD's kit for my '04 YZ250F now I use the recommended #185.

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