Hard to Start

[lagermann]

I own a 1987 K100RS. When I bought it, the battery lasted over 2 years.I do not ride that much, but when I want to ride; here's the problem: The battery will not hold a charge.The Battery Tender will keep a charge for only a week. A quick charge will get me on my way. I may ride 50-100 miles, park it, and the battery will be good for only 12 hrs. Also, I changed the starter relay. Where's the juice going?

[PGlaves]

Two possibilities:

1. The battery is bad and won't hold a charge.

2. Some circuit or device is draining the battery.

To test for battery drain you will need an ammeter. Many Multimeters are available that have an ammeter function - get one with up to a 10 amp range.

Then disconnect the ground cable from the battery. Set the multimeter to the 10amp scale and connect the negative lead to the battery post and the positive lead to the ground cable just disconnected from the battery. A key-off reading of a few milliamps is normal (clock and such). This would signal a bad battery. Heavier current signals a battery drain you will need to trace.

You can start to find the drain by removing fuses one at a time to see if the current flow drops when you pull a fuse. If it does, the drain is in the circuit on that fuse.

If it is not in one of the fused circuits, then disconnecting connectors is necessary. A wiring diagram would be very helpful at this point.

Good luck.