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Just a general jetting question

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i just did new piston, rings, shimmed the valves, put an fmf q4 on and drilled holes in the air box. how much more power gain will i notice if i re-jet the bike?

oh and i have a 2003 wr250f. all free mods

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no one has to be exact i was just wondering if anyone has done this same thing and if they noticed any difference in power when they rejetted the bike correctly. or if it even needs rejetting?

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i have an 06 wr with a Q4 silencer and the holes drilled in the airbox. you will notice it pulls much harder after re-jetting.

i fitted the JD kit on mine well worth the money.

i run at sea level - 500 feet

and temps 0-20 degrees cent.

if you are at similar i will post my set up for you to use as a baseline

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heres the settings i used with good results

i ended up using the red needle after mucjh trial and error and found the bike ran far better with it (JD recommend blue needle)

obviously the fuel screw setting will have to be set to your particular bike

good luck

Mixture Screw 1.5 turns out

Pilot Jet 42

Main Jet 175

Needle Red Needle 3rd clip from top position

Leak Jet 40

AP screw adjusted as per manual + 1 turn further out

Air box snorkel & cut outs removed, AIS Kit removed & ‘O’ Ring mod on carb

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