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Jetting Reccomendations...09 Yz250F

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The bike is stock haven't done anything to it...But on the deceleration it backfires.When its warmed up and i go to give it gas it likes to bog then rev up quick.Checked Valves They were fine,Checked exhaust no leaks or cracks,checked Boot on exhaust,and the fuel screw.I found this chart but i dont know if it would be good for my state im in new jersey.

Jetting changes

Pilot-----stock 40 to 42=one richer

Needle--stock 4th from top to 5th from top=one richer

Main-----stock 178 to 180=one richer

Fuel screw--from 1.5 out to 2 out=richer by a half turn

This guy said it was a big difference after he did that but i couldn't find out what state he was in...:lol:

Let me know what i should do if i should get a jet kit or something im not good with carbs.Im only 15 so im learning.

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i think the person who told you that is giving your young mind false info.lol my 09 came with a 42pilot,not a 40.here is what you need to do.do as william stated,then,if the bike needs jetted,i would either buy a jd jet kit,orthis is what worked well on my sons 09.45pilot,180main,55leak,red needle from a jd jet kit,fuel screw 2 turns out.this was done using renegade mx4 leaded/oxygenated fuel.it doesnt matter what state you ride in,as long as your not going to go up in the mountains,or super hot or cold climates.the 45 pilot helped ours quite backfiring,but wa mainly done because we race arenacross in the midwest,and it is often very cold,even in some of the arenas.good luck and keep us posted

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if you search some of my older posts,i have listed several yr model 250f yammie carb fixes.

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