Topic: any ideas?

[000jeremy]

My 77 cb550f died while idling at a light this afternoon.  It appears that it lost power.  I had the feeling that the battery hadnt been charging since slowly the electric start stopped turning the engine over, turn signals stopped flashing, horn didnt work, over the past couple weeks of riding....so I went for a long ride yesterday and tried to keep the rpm's up to see if it helped.  It didnt.  Today it died at a light and didnt even have enough power to kick start until I let it sit for 20 mins or so.  There dont seem to be any problems if I keep the rpms around 2k.  I have a new yuassa battery that is less than a month old, a solid state regulator/rectifier that is less than a year old.  All of the fuses seem ok.  Any ideas?

Thanks in advance,
Jeremy

[mystic_1]

Time to bust out the voltmeter and take some measurements.

Measure battery voltage with the bike off, then start the bike and rev it up above 3000 or so and re-measure battery voltage.  If the voltage is higher with the bike running than you're getting at least SOME charging.  Your workshop manual will have more detailed test instructions.

mystic_1

[bistromath]

Do you have an aftermarket headlight? 3-ohm coils? The 550 has a notoriously marginal charging system, and adding aftermarket components can easily overwhelm it. I keep mine on a tender for that reason.

If you have a multimeter that measures current, you can unplug the positive lead from the battery and put the ammeter in line with it. This will tell you directly if the battery is charging or not. It should "break even" around 2000RPM.

[Hush]

Bike should "make" charge over 3000rpm so idling around town can kill it but many other possibles.
Old favorite is pull all the fuses, they may "look" alright sitting in their case but take them out and give them a good clean up, they build up some form of crud just sitting their and lose their conductivity over time.
Check battery leads, remove them and use some DI-ELECTRIC (sic?) grease on the connections to ensure a good connection, remove your earth lead from the frame (if possible as some are attached to the engine bolts) and ensure the area around that is clean.
After that as Mystic said it's mulitmetre time starting at the 3 yellow leads from the alternator to the rectifier...have fun.