I have a 1998 Lt-F4WDW(250cc). It has 5,165 (s)miles on it.
Early this year it started running weird......starts fine(hot or cold).
You go to take off and the motor would sputter just off idle(throttle opening), you let off the throttle and it would go right back to idling just fine.
Now here's the really weird part, if you turn the switch(key) to lights it would run just fine, switch it back to just run(key) and it would go back to sputtering!??
Well after taking everything off the ATV and not finding anything wrong I put it back together and while reinstalling the battery I see it's completely dry, I have a new battery setting on the shelf just because you can't have enough batteries in your life(lol) anyway I put the new battery in and start the ATV and it runs like new again............I don't even think about the battery being dry...........the ATV runs great from Oct. to the end of Nov.(~200miles) and starts sputtering again.....so now I'm having to run with the lights on to get anywhere on this thing, It get's worst, I'm having to run with all the lights on (Headlights and aux-lights) or it won't move(just sputters).
So today I pull everything off the ATV again and when I pull the battery it's not bone dry but it doesn't have a 1/2" of liquid in it, I have a feeling that just adding distilled water to the battery will cure the sputtering again but my question is why is the liquid boiling out of the battery?

 

check voltage output to battery. possibly over charging

 

Yeah, I kinda figured that, but what's causing the over charging.....what parts control the charging? What can I change to fix the over charging(no guessing on which part cause they cost alottttttt).

 

I'd look at a parts fiche and see if the machine has a regulator.
motorsportssuperceter.com for a fiche.

 

it has a voltage regulator/rectifier. use a volt meter and check the output on battery cables with it running.

 

i have the same issue with my lt250, but my question is, where is the regulator? i can not find it lol. and, what sould the voltage be going out of the battery?

 

Its under the front bodycover/fender/left side facing the front of
the ATV/right under the handlebars.