My buddy has a 250 trail boss. Each time you run this thing, the battery will go dead. ONce it does so, the reverse and neutral indicators do not work as well as the lights. It seems as though everything is running off the battery, including the cooling fan. This worries me, I am afraid that when the battery is low that this may overheat? What could be causing this, because as of right now we just charge up the battery and it is ok, as long as you dont ride it for a long time. ANother thing is that the cooling fan turns on as soon as you turn the key on even if the motor is cold. Does anyone have any ideas. I know I am a noob, but any help would be appreciated. Thanks in advance

 

Sounds like its not charging while running.
Got a volt meter? If you do, then hook it up accross the battery terminals, and find the static charge. This is what youll read with the key off, just sitting there. Should be about 12.3 or better, depending on air temperature and charge on the battery. Now, leave the voltmeter hooked up, and start it up, in neutral. At idle the volts shouldnt be much less than the static charge...ideally it should be more, but sometimes stators just dont get there, especially on older quads. Now rev it up slowly, and watch the volts, youll see when it starts to charge (the voltage gets higher than the static charge). This is where the motor needs to run, in order for the battery to charge.
If it doesnt come up, over the static charge, the battery could be bad ( doubtful), the voltage regulator is bad(likely), or the stator isnt putting out anything (also likely).
Let us know what you find. Its possible to ohm out the stator to check if its any good, and its posible to load test the battery to check whether its good or bad.

 

Be careful,on my 2004 400 sp if I run it with a bad battery it blows the headlamps all 3. Spoke to the dealer and he said this happened to him when he pull started some new bikes without the battery installed. The two low beam bulbs could only be purchased through the dealer @ $27.99 ea