New member here
I bought a 1976 r75/6 for a younger member of my family to ride. The bike is a little rough but it ran okay.
We changed all the fluids, except the fork oil, replaced the petcocks and fuel filters as well a cleaning the carbs. We also replaced the battery.
We were ready for a road trip. About 200 miles from home the battery went dead and the bike wouldn't start. I was informed that earlier the GEN lite came on dim, then bright and then went off.
The voltmeter reads 10 volts on the battery. We jumped the battery and start the bike. I measured the voltage across the battery with my digital voltmeter. On the both the 20 volt and 200 volt scale I read O.L (over limit)
I tried charging the battery by connecting it to my running bike. The battery did not seem to charge.
Did I over charge the battery and destroy it?
It would seem I should read somewhere around 13.5. Volts across the battery on the running bike.
I have been reading up on the charging system of the airhead and get the impression this may be something minor.
Currently the bike is stored and I plan to retrieve it next Saturday.
Any suggestions will be greatly appreciated
Some common charging system areas to check. In no particular order they are.....
• Bad battery. Most all the m/c batteries are made in China and their quality control is terrible. It's very possible to have a "new" battery that's bad. Take it back.
• Have you swapped the "bad" battery with the one in your bike ?
• If you purchased a flooded cell battery, did you charge the battery for the specified time before placing it in the bike ?
• Did you use your home charger on the new battery ? What is the output of the home charger ?
• Did you inspect BOTH battery cables carefully at BOTH ends ? Are all 4 terminals clean and shiny ? Corrosion can get under the cable jacket and come out at the other end, ruining the entire cable. Carefully inspect the ground connection at the gearbox.
• While you have the battery out, remove the front engine cover and starter cover. Check the alternator brushes. Check the 4 rubber rectifier mounts. (These are typically replaced with metal.) Check the 6 diodes on the rectifier board. Check the grounding of the rectifier board. Check the red wire that goes from the rectifier board to the electric starter for good connection.
• Replace the GEN light bulb in your instrument cluster.
• Install a solid-state regulator. I've had very good luck with these (Ebay #272655228783) for under $20.
• You cannot test a battery with a voltmeter, but you can test the running charging system at the battery. You should measure slightly above 14V at 3000 RPM. (This will be ~1V higher than the OEM dashboard voltmeter indicates, if fitted.)
► Your issue could be one bad component, or it could be the sum of 100 poor connections. It is the "best practice" to treat every single electrical connection you re-plug or re-assemble with a corrosion inhibiting compound such as No-Ox-Id ( Here On Amazon ) which will defeat the corrosion left by riding for 40 years in the rain. Use it on both ends of both battery cables, the 3 pins on the regulator, the block connector on the rear of the speedo/tach, the ends of the fuses in the headlamp shell, contacts on instrument bulbs... in short on every single electrical connector you touch. A 2oz tub is enough to treat 50+ motorcycles.
Hope this helps.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Thanks Wobbly! What have me confused is the fact I get an over limit reading On both AC and DC settings on my meter with the bike running.
My initial diagnosis was done in a Walmart parking lot. Once I get the bike home I can offer more concrete symptoms.
Thanks Wobbly! What have me confused is the fact I get an over limit reading On both AC and DC settings on my meter with the bike running.
My initial diagnosis was done in a Walmart parking lot. Once I get the bike home I can offer more concrete symptoms.
Cheap digital voltmeters are often tripped up by the EMI given off by older analog ignitions, especially if you have removed the resistor spark plug caps. If you really want to do this, you'll need to find an accurate analog meter. You'd want to use the 20VDC setting, since all batteries are DC.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
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