Motorcycle Repair: Yamaha XS650, xs650 yamaha, concrete job

Question
i got this beat up broken down yamaha 650 special. in part trade on a concrete job. i replaced the brakes, cables , battery, and some gaskets and got her fired up and running. the problem i'm having is the battery doesnt want to stay charged, but the test guages tell me when its idling that the system is charging fine. what is next step in finding why my system is charging ? its a 1982 XS650 yamaha

Answer
Hi Jim,

The XS650's are pretty cool MC's.

Use a multimeter and check battery charge is at 2000 RPM. Charging voltage should read 14.5 to 14.8 volts @ 2,000 RPM. A fully charged battery will read about 13.5 Volts. Charge should be at least 12.5 volts, or 2.1 volts per cell.

Check battery voltage with a multimeter and specific gravity of each cell with a Hydrometer designed for MC batteries.

Get a copy of a service manual. It has illustrated procedures for all repairs and electrical testing.

Visit the following websites:

www.mikesxs.net/mikesxs-electrical.php?category_id=2.6

www.electrosport.com (Electrical Fault Finding Chart)

www.bikebandit.com (Parts Microfiche)

www.yamaha-motor.com (Parts Microfiche)

Respectfully,
Mark Shively