Look for some help with the electrical system. My buddies 91 RK Classic, battery runs down after about a week of riding or earlier if he starts it a lot. He changed the battery about 4 months ago and the voltage regulator about a month ago. How can we check the charging system? What else can check?

 

Easy check if you have a voltmeter. Remove the seat and check voltage across the battery without the engine running, should be 12.6 VDC at least, start the engine and it should go up to 13.8 VDC to 15 VDC.

 

okay thanks

 

Another thing to check is for "battery draw" If you are using a test light, put one lead on the battery negative terminal and the other on the on the cable end ( cable disconnected), If the light is bright you have a constant draw. If the light is very dim that is just your keep alive circuits and is ok. If you use a DVOM you will get a 12 volt reading but you need to check for
resistance. That should be very low. Some modules are designed to go to sleep after a peroid of time. If they don't they will show a large amp draw. If you find you have a drain, start removing and reinstalling your fuses one at a time. The one that kills the draw is the circuit you need to troubleshoot.
Hope that helps.