Motorcycle Repair: problems starting, honda nighthawk 650, 1985 honda nighthawk 650

Question
Greetings motorcycle master. I am having problems starting my 1985 Honda nighthawk 650. I can jump start it ( pushing it down the street and poping it into 1rst gear) every time. I replaced the battery and spark plugs. I bought a battery charger and charge the battery occasionally and it seems to start sometimes that way. I try to start it multiple times and eventually the batteries juice runs out. I think this may be a problem with the starter motor. If so can you help me diagnose b/c no one will work on my bike because some parts are discontinued thus I am to perform surgery on my bike without a whole lot of knowledge of it.

Answer
Kevin,

-this seems to be a recurring problem with the
older Nighthawks. Part of the problem is
the low charging output. These bikes don't
charge the battery much until 2500 rpm.

-The battery has about a 10 amp current loss constantly
when idling. When you stop, the battery doesn't
have enough juice for the spark and the starter
together, that's why a push start works.
Some batteries fail under load,
you might want to get it tested for that.

-It may help to go around and clean all the
connections to the battery, solenoid and starter.
Get some emery paper or a small file and
clean any cables and frame grounds.
Also keeping a 1 or 2 amp trickle charger on it
might help.

-The starter motor may need some work just so it
doesn't draw more current than it should.
Cleaning the starter up internally and
possibly new brushes might help it to
spin faster and use less current.

-try checking the plug cap resistance,
should be 5000 ohms or less.