I have a 1990 Yamaha moto4. My question is:
Is there a way to test whether my charging system is working? My battery will not hold a charge and I am not sure if it a battery problem or a charging problem. I have no idea how old the battery is. It was in the atv when I bought it last year.

 

Turn ATV key on and check voltage of battery, it should be around 12v, then start up atv and check the voltage again, if it reads 13v-14v while running then its charging.

 

Good advice.

Or you can take one of the battery cables off and if it quits running your charging system is not working.

Both ways will work, your choice.

 

Sorry for not replying back sooner with my thanks.

I appreciate the responses and either test is simple enough for me to do.