I have a 1999 Suzuki 250 four wheeler...It started running awful but when the headlights get turned on it runs smooth. If you turn headlights off it bucks and sometimes backfires. Now it is starting to do this with the headlights on...but if your shut it off and restart it...it will run for few feet (headlights have to be on)...I recently put a new battery in it and new sparkplug. Please any advice..

the key when on sends power to the ecm electrical control module this in turn sends it to the coils and then to the spark plugs get a wiring schematic for your quad and rehook them up to the key

put rocks in where? if the gas tank then your petcock filter is probably clogged

when engines not running turn the gas off . And it sounds like you need to adjust your throttle pin that goes into the carb take the clip off the pin and move it down one good luck

Okay first your other responses are completly illiterate ok if the drive shaft is spinning that means the motors running for all of you other answerers that means gas is going through the carb into the engine and it's working perfectly fine. Now to answer your question if the rear wheels aren't spinning you probably have the same problem I'm having with mine at the moment you've drivien it too hard and the gears on the bottom end of your drive shaft aren't warn but inside the bell housing of your rear end where the drive ahft enters the gears are so worn you can't feel them in that case you would disconnect all of your sub frame conecters and the back shock then your rear end will come away from the four wheeler check the gears I told you about and if they are worn go buy new ones. Problem solved

If your talking about air fuel mixture screw a good place to start is turn screw clockwise till stops.back out 1 1/2 turns get bike running see how throttle responce is.If bike is still sluggish then try 1/2 turn increaments counterclock wise till bike runs smooth.Good luck ...Brian

Rebuild your carb make sure floats are clean and no dirt floating around inside of bowl

CDI BOX

ok buddy on carb will be a screw mixture screw fiddle with this and get back to me

The air screw and throttle screw are NEVER supposed to be tightened up at all. Doing this can damage the seat. Only screw the air screw and throttle screw in until they LIGHTLY seat. Now turn each adjuster one and one half turns outward. Chances are you will need to replace the adjuster screws to get the bike to idle properly. Yeah, the ends look okay but that little ring indentation where the screw was tightened down matters a lot. If re-setting the screws fixes the problem you should consider yourself lucky.

id start by getting a set of feeler gages and set the tappets up and try that , also check compession