1990 trailboss 250cc 2 stroke 2x4. can anyone give me an idea where the altenator is located. I just need to remove and replace it. thanks

 

There are tests which can be done, which can narrow down what the problem is , before you spend lots of money on parts which may not be bad.
Your problem of not chargeing sounds more like the voltage regulator than the stator. Did you ohm out the windings of the stator? You say theres no voltage with the battery disconnected, but there needs to be a complete circuit to get voltage. If your battery is still good, hook it up, and put a voltmeter across the terminals...what youre reading is the static voltage, now start the motor, and leave the voltmeter hooked up, now slowly rev it up to about 3000 rpm, and watch the voltage. Does it get higher than the static charge?

The stator (alternator), is on the end of the crankshaft, under the cover.
I dont have a service manual for this quad, but maybe someone else can come up with the specs for ohming the stator. Normal range is about 100 to 300 ohms. If it ohm checks good, then its probably good. If its shorted or open, then its probably bad.
The difference between a stator and an alternator, is the stator has permanent magnets, and the alternator has electomagnets, which can be cycled on and off. Stators are always on, when the crank is spinning, and rely on rpm to produce voltage.