Motorcycle Repair: 79 Z50R NO SPARK, honda z50r, plug cap

Question
I HAVE A 79 HONDA Z50R WITH NO SPARK. I PULLED OFF THE COIL AND GROUNDED IT TO A SMALL 12V BATTERY. WHEN I TAP THE POWER WIRE ON THE HOT SIDE OF THE BATTERY I CAN GET IT TO JUMP A SPARK THROUGH A NEW PLUG BUT NOT CONSISTANTLY. IF I HOOK UP MY MULTI-METER TO THE WIRE ON THE ALTERNATOR THAT GOES TO THE COIL IT WILL ONLY READ 0.4-0.7V WHEN I KICK IT OVER.I CHECKED THE SAME READING ON A 1983 XR80 THAT RUNS AND IT READS 2.3-2.8V . NOT SURE IF THE COIL IS BAD OR LOW VOLTAGE FROM ALTERNATOR. THE POINTS SEEM TO BE IN GOOD SHAPE.

Answer
Don,

use a new or good spark plug. (.024" gap)
try disconnecting the kill button wire,
(black/white) check for spark again.

Check for spark with the plug cap off,
it could be faulty.

Clean points, gap at about .014"
They should just break open with
the flywheel timing marks aligned.
Make sure gap is not so wide that
the points fail to close.
Check the black and black/white wires
for shorts/breaks.

Check that flywheel key is okay.
Check that flywheel magnets are clean
and have magnetism.

Try temporarily disconnecting or replacing the condensor.

The output of the lower coil depends on
the flywheel magnetism and the rotational speed.

The upper ignition coil is better
tested at 6 volts or on the bike
to be safe.
Also make sure the coil grounds are clean.