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Warm Engine Surging???
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Posted by: ARC_89TRX250R

Hey all,

Anyone know whats going on with your machine if its having troubles idling down after it warms up?

Once i get my engine up to operating temp after i pull the clutch in to slow down the engine surges up and down and wont drop to idle. once im moving slow and let the clutch out a second its stops the surging and then it idles at normal speed.

My plugs dark but not all foweled up and im running a fmf sst and silencer along with a k+n closed lid, stock carb with 160 main stock pilot, 2 grove down on the needle.

any sugestions? i had this before my rebuild and now i got the same thing again.
is it a wrong sized pilot?

Thanks

Drew

Posted by: fireburns99

sounds like your idle adjustment is off. Just turn it in i believe, it may be out though. (it's the little choke knob)

Posted by: EXtreme-

"The ideal procedure for setting the screw in the correct position is to warm up your ATV engine to the proper operating temperature. Then turn the idle up so it is idling about 500 RPM’s higher than normal. Next turn the airscrew all the way in until it bottoms out, once bottomed out slowly back the screw out a Ľ turn at a time (give the engine 10-15 seconds between each Ľ turn of the screw, to allow the engine to catch up with the adjustments). Continue backing the airscrew out until the engine idles at its highest RPM. The preferred setting window is between 1 and 2 turns. If the engine idles at its highest RPM from 0-1 turns out this means the pilot setting is on the Lean side and a larger pilot jet should be installed. If the engine idles at its highest RPM at over 2 turns out, this means the pilot setting is on the Rich side and a smaller pilot jet should be installed.

If you get no RPM fluctuation when adjusting the air screw there is a very realistic chance that there is something clogging the pilot/slow speed system. Clean the system thoroughly with contact cleaner and blow out with compressed air. Carburetor must be disassembled.

If the airscrew adjustment process is unsuccessful and leaves you confused. Set the screw at 1 ˝ turns out and consult a professional for further assistance. "

Posted by: matt250r21

Sounds like you could have an air leak. Check your reed cage gaskets and your stator side/crank seal (main bearing seal).

Posted by: 1fastprototype

you have a bad seal somewhere. high reving is a tale tale sign of an air leak.

Posted by: EXtreme-

assuming there's an air leak, what's the best method of determing the location? How about the old "carb cleaner trick"?

Posted by: ARC_89TRX250R

Thanks for the ideas all, ill give it a shot tomorrow