Magna v30, 1984 problem. Funky charging system

I have a technical question:
I have a 84 magna and lately a problem with the charging system has
come up.
The bike starts right up, but when it gets hot it sounds like the
battery is dying out. So i let it cool down a bit "say 20 mins" and
then it starts right back up and sounds great, but unless i give it
that time it sometimes doesn’t have the might to turn over. I just put
a new battery thinking that would do it but that didn’t help. I bought
a used voltage regulator and still the same problem. Is there anything
else I should be looking at, maybe the stator ??
TIA,
Little lost with this one....

 

Have you done a charging voltage check across the battery terminals
with the engine running? If you see the voltage rise from 12 volts to
about 14.5 or 15.0 volts and then the voltage drops off sharply as the
engine RPM increases above about 5000 RPM, and then the voltage picks
up again and again and again every time you roll the throttle on and
off, your charging systems is OK...

If theres's no problem with the charging system or a weak battery, the
engine is probably pre-igniting on the compression stroke. The spark
plugs electrodes are so hot they are glowing red and acting like a glow
plug in a model airplane engine. The gasoline vapors in the combustion
chamber light off before the spark ever occurs. This makes the
starter's job very hard.

Are you sure you have the right heat range spark plugs in your engine?
Spark plugs that are one heat range too hot will make the engine
preignite.

You may have cooling system problems, the radiator might be crudded up,
the thermostat might not be opening completely, but, as long as you
have enough coolant in the engine and it's all the way up to the normal
in the expansion tank, I would recommend either running premium gas if
you're using regular now, or I would recommend opening up the idle
mixture screws about 1/2 or one full turn. That will cool down the
engine more than you would expect.

An engine will pre-ignite on lean idle mixture when you try to start
it, so that's the reason for richening up the idle mixture.

The idle mixture screws are probably still hidden under the EPA
anti-tamper plugs. One my Suzukis, Yamaha, and Kawasaki, I drilled a
pilot hole in the EPA plug, screwed a small sheet metal screw into the
pilot hole, and then pulled the screw and plug out with a pair of
pliers so I could adjust the idle mixture screws with a screwdriver.

 

Oh yea,
Thanks for the reply, turns out the starter was falty and was
draining the battery. The tricky part was that it actually worked so
that would be the last place i would have looked. The bike still gets
plenty hot though, if it wasn’t for the fan it would cook and melt.
Thank you again for sharing your knowledge, it was something I will
copy and paste for a rainy day..