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The Cripple
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8,772 Posts
Cb700 is right. Check voltage of the bike before starting, during starting and while idling. If the voltage changes significantly during any of these, the battery is bad.

Also check voltage before and after the rectifier to compare against factory specs.
 

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Why's everything on fire?
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2,361 Posts
What are some signs of it being bad?
Not actually going past break-even at the specified RPM (see service manual for the exact number) or not going past break-even ever (i.e., it never starts to charge the battery.)

Bad diodes in the rectifier portion of the integrated regulator/rectifier can cause it to drain the battery; this is because the only difference between an electric motor and an electric generator (for the purposes of this discussion) is which way the electricity is flowing. Diodes are one-way gates for electricity. When they are working properly, power can only flow from the alternator to the battery, but one of their failure modes is to allow power to pass both ways. At that point, the battery will (unsuccessfully) try to power the alternator as if it were an electric motor and power will be drained accordingly.

Just to drive the point home about the above, here is a Ford alternator that has had its regulator/rectifier removed and a motor controller installed in its place (i.e., power is deliberately being fed back into it) with no other modifications:

http://www.youtube.com/watch?v=r1NIVKa7mZY

Also: Check the connector at the regulator/rectifier - often someone has forgotten to clean and treat it and it's started to melt from the heat generated by the corrosion on the contacts. Assuming it hasn't just melted period - this is not an uncommon problem for bikes of all kinds, but certain model Hondas do tend to be more susceptible than others.


 

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1 Posts
Take the spark plugs out and turn over the engine with the rear wheel while in gear to make sure the engine is still free.

Goog - the 650/700 starter will spin even if the kill switch is set to off when you jump the two big terminals together with an appropriate sized conductor. The power path for the starter is battery positive to solenoid to starter, without anything other than the solenoid interrupting it.

Only other electrical possibility is that the ground between the engine/frame and battery is shot. Everything else is going to be mechanical failure; bad starter, locked up engine.
I have a 1984 Honda nighthawk 650cc that won't start. I thought it was the battery but I replaced it and it won't start. I'm assuming it would be the starter because the solenoid clicks but the starter doesn't try.
I'm normally a car mechanic but this is my starter bike. Before I go replacing parts am I missing anything?
Same with mine. thanks to one of the posts I checked the gears. first gear did not want to engage so I think it was the motor that was stuck. I pressed the clutch and put it on second gear and push it back and forth while slowly releasing the clutch. then I tried to start it and thank goodness, and some of the comments, it started.
 

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Wanna free cat?
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1,020 Posts
Whooooo..Praise the Lord for small favors
 
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