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carb problems? motor running rough

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hello all,

 

I have recently purchased a 1999 kx250. 

 

The previous owner had it since new and pulled the motor out to run in his go kart. IF hes telling the truth, the motors done only 40-50 hours and the frame 10-ish. It has a FMF Fatty chamber and FMF Muffler, weighted flywheel, VForce 3 Reeds, 52 tooth rear sprocket, new piston and rings and new clutch.

 

i took it for a first run last weekend and when the throttle is open, it goes hard but when on a hill descent with no throttle, the engine feels like it wants to still push me forward in a 'pulsing' type fashion like its getting drips of fuel. When its hot its idle is also very pulsed, not a smooth purr like i thought it should be.

 

also the bottom end feels alot less than i remember when ive previously ridden an 07 kx250 and also a 05 cr250.

 

 

can anyone help with any ideas or solutions?

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hello all,

 

I have recently purchased a 1999 kx250. 

 

The previous owner had it since new and pulled the motor out to run in his go kart. IF hes telling the truth, the motors done only 40-50 hours and the frame 10-ish. It has a FMF Fatty chamber and FMF Muffler, weighted flywheel, VForce 3 Reeds, 52 tooth rear sprocket, new piston and rings and new clutch.

 

i took it for a first run last weekend and when the throttle is open, it goes hard but when on a hill descent with no throttle, the engine feels like it wants to still push me forward in a 'pulsing' type fashion like its getting drips of fuel. When its hot its idle is also very pulsed, not a smooth purr like i thought it should be.

 

also the bottom end feels alot less than i remember when ive previously ridden an 07 kx250 and also a 05 cr250.

 

 

can anyone help with any ideas or solutions?

 

Sounds like maybe the pilot circuit is clogged or needs to be rejetted? I'm sure the carb could use a good cleaning anyways. The main jet controls 3/4 - full throttle which sounds like its acting OK, but the pilot jet controls idle to 1/4 throttle so this is where it sounds like your having issues. I'd clean out the carb, make sure your air filter is new/clean, and see what happens.

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i have returned all of my settings to stock - middle clip, std jets main and pilot, 1.5 turns on air screw and gave everything a good blow out

 

still having same issues? (maybe a little worse)

 

still unsure what to do. have read that a surging idle is a lean condition?

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