Electrical issues - need help

mmairhead · Post by **mmairhead** » Sun Jan 02, 2011 4:41 pm

My 1978 R80/7 wouldn't start today. I jumped it and it started right up but when I removed the jumper cables, it immediately stalled. I just moved into an appartment so I lost my garage. Before I get in too deep in the car port, does anyone have any thoughts on where to start looking?

schrader7032 · Post by **schrader7032** » Sun Jan 02, 2011 5:08 pm

First place I'd check is the battery. Is it known good? These bikes need a battery to run...they're not like cars where once started, they'll run until you shut them off. Check your battery with a voltmeter across the terminals. It must read a minimum of 12.3 or so. But that's only part of the story. What does it read when you put a load across it, like when you try to start it? If the voltage drops to below 10v, you probably have a bad battery. I believe places like AutoZone can even test the battery.

First start there. Next, be sure you have good cable connections to both terminals and to the ground connection at the back of the tranny. Don't tighten too tight at the back of the tranny...easy to strip. Clean and secure snugly. If the cables are corroded, they need to be replaced. Often times, they look good on the outside, but the corrosion has eaten up the inside, reducing the net area to transfer the current.

See if that helps.

Once started, you should measure the voltage across the battery terminals with the engine reving to above 3K RPM. Should read 13.5v or even better, 13.8-14v. If not above 13.5v, you have a charging issue, either weak charge or no charge at all. That should be addressed once you've figured out the battery and cables.

doublejj · Post by **doublejj** » Wed Jan 12, 2011 6:38 am

By what you have posted, chances are, not only do you have a "dead battery", you have "bad dead battery". I'd bet it's shorting across its cells. Hence the immediate stall after removing a force power charge. Had a camper do this this past summer, included burning out fuses in the camper (they couldn't believe it could be the batt doing it). The end result was it was only a very bad dead battery that had been sitting for awhile. A change of Batt was all that was needed.