1974 T500 electric problem

[RossB]

Hi Gents
Just picked up 74 t500 10000 miles hasn't run in 30 years rebuilt carbs purged oil lines cleaned tanks
Tried kicking over new battery spark ok pulled points cleaned them (getting new ones and condenser)
Here we go now no power to ignition no neutral light. Put meter on battery when I turn ignition on draws down to zero volts then turn switch to parking power slowly comes up to 12 volts then rear light goes on. When I checked +and- terminals positive was broke replaced and same issue. All was good till I took points out ,checked power to fuse no voltage. Thanks for all the help!

[jabcb]

Start with making sure your new battery has a full charge — no point in ruining a new battery while you figure this out.

The bike may have been parked 30 years ago because of some unknown electrical problem.
The problem may be unrelated to the work you just did.

Replace the fuse & disconnect the points.
Check the voltages with the key in each position, and with the lights on & off.

Give the wiring a look over to see if you can spot any problems.
Look at the wiring near the battery box for possible worn insulation & intermittent shorts.

Its easy to incorrectly wire up the points.
There are some posts with pics on how to connect them. Will look for them when I have some time.

The wiring diagram is here:
viewtopic.php?f=29&t=4743

[RossB]

Thank you printed up wire diagram will check wires again everything is unmolested I'm 2nd owner just weird no power to fuse?! Watching voltage rise from 0 to 12 volts in p mode then rear light comes on the wiring can't be any simpler
did pull points wires off same gig will do what you said just weird no juice on fuse.
Thank you!

[jabcb]

There is some info on wiring up the points here: viewtopic.php?f=2&t=11783&p=155895&hilit=points#p155895

You may have a broken wire. Look for voltages to narrow down where things don’t make sense.
If there is a point where most of the wire strands are broken, it may conduct enough current to light the taillight bulb but not enough to power everything.

A few years ago I got vintage bike that had a bad fuse. The fuse looked perfectly good — the fuse wire was broken in the end cap where you can’t see it.

[rngdng]

Ignition switch???

[ConnerVT]

Put meter on battery when I turn ignition on draws down to zero volts then turn switch to parking power slowly comes up to 12 volts then rear light goes on.

Just where did you put the meter leads? Was the meter in the correct VDC setting? A battery should never "go to zero" volts, even if it is almost completely shot. And if it was, it likely wouldn't then recover to light a tail light.

Something is either wired/connected completely wrong, or you have a bad connection somewhere (first suspect - the original style fuse holder). Been down the road with both of those issues.