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2007 KX250F Jetting Help?

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Hi guys. I've just bought an '07 KXF, and have changed the pilot down a size from stock (The bike was backfiring pretty badly on decel'), and adjusted the fuel screw. The backfiring has decreased to only a slight popping noise now. The bike is running much better, and starting much easier which is good, :applause: However, If I crank the throttle open really quickly there is quite bad bogging, and the bike cuts out occasionally:thumbsdn: . I've read about guys with boyesen quickshot covers, and I was wondering whether buying and fitting one would eliminate this problem? Also if i changed the jetting from here, which jet would I need to do first?

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y would u go down if its backfiring on decel? should go up.....to check to see if u have the right pilot setting...turn fuel screw all the way in...if idle smooths out more than 2.5 turns----> go bigger....if its less than 3/4 of a turn get a smaller pilot...other than that here is a good basline from team green and pro circuit

Part---------------Stock------ Pro Circuit--------Team Green

Main Jet------------180----------170-----------------175

Needle-------------NCYU--------NCYS---------------NCYS

Clip Position-------2 or 3----------4--------------------4

Pilot Jet-------------40-----------42-------------------42

Fuel Screw (out)---1 3/4----------3-------------------2.5

Leak Jet-------------60-----------50-------------------50

no need to do everything

try it out with the stock jet needle and leak jet

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Thanks racer. I rode the bike with the smaller pilot jet, and the backfiring has almost stopped. The bike seems to run really well with the stock jets, and I don't get the bog when I ride, coz I don't give the throttle an absolute kicking. I'll have to try a few of the configurations that you've sent. maybe they'll get rid of the bog! I'll also have to check the fuel screw position, and then make the necessary change with the pilot. Thanks for all the info, greatly appreciated. :applause:

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After riding the bike with the smaller pilot, I checked the plug condition, and it was white(running lean), so I changed it back to stock, and adjusted the fuel screw out 2&3/4 turns. Runs sweet, starts easily, and there isn't any problem anymore. I never get that bogging I described when I ride, so I figure that it's nothing to worry about. Thanks for your help. :bonk:

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