akamor Posted July 22, 2010 Share Posted July 22, 2010 Hello All, Thanks in part to everyone on this forum my 1980 XS400 is running strong. Now that I have the mechanical issues figured out I need to work on the electrical system. The biggest problem is that after riding the bike for only about 30 minutes the batter begins to die and it becomes hard to start with the electric start. I am fairly confident the issue lies in the alternator. When I put the engine at 2000 rpm and measure the voltage across the battery terminals I typically see it jump to about 12.8 volts, but never higher. To me, this implies that the alternator is not performing properly. What steps should I take to troubleshoot the alternator? Thanks, Adam Link to comment Share on other sites More sharing options...
Moderator drewpy Posted July 22, 2010 Moderator Share Posted July 22, 2010 this has been dealt with many times. its usually the voltage regulator Link to comment Share on other sites More sharing options...
Ebola Monkey Posted July 25, 2010 Share Posted July 25, 2010 Run an extra ground cable to the chassis, and start with a fully charged good battery. I went through hell with my wife's bike with similar problems. Tested and/or replaced everything in the charging system with no real results. Ground seemed fine, but adding another seemed to cure it. If it doesn't work you're only out a couple bucks, which is cheaper than any other part in the charging system. Link to comment Share on other sites More sharing options...
akamor Posted July 28, 2010 Author Share Posted July 28, 2010 Run an extra ground cable to the chassis, and start with a fully charged good battery. I went through hell with my wife's bike with similar problems. Tested and/or replaced everything in the charging system with no real results. Ground seemed fine, but adding another seemed to cure it. If it doesn't work you're only out a couple bucks, which is cheaper than any other part in the charging system. Could you explain what you mean in more detail? One end of the ground wire should attach to the frame. Where does hte other end attach to? Thanks, Adam Link to comment Share on other sites More sharing options...
Ebola Monkey Posted July 28, 2010 Share Posted July 28, 2010 Could you explain what you mean in more detail? One end of the ground wire should attach to the frame. Where does hte other end attach to? Thanks, Adam The negative terminal on the battery. There's a screw just a couple inches away under the seat that I attached mine to. Link to comment Share on other sites More sharing options...
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