Here in the US the 80 got the TCI ignition. Your being an Australian bike with points you may want to use a 79 wiring diagram.
That's what I'm looking at now.
From the battery power flows on a red wire to the fuse box. At the fuse box power flows through the main 20 amp fuse and out a red wire to the main switch.
There are several points along this red wire power can get lost. Any connectors can be dirty or loose fitting. The key switch itself can be dirty. It can be taken apart and cleaned.
At the key switch power flows out on a brown wire and a blue/yellow wire. The brown feeds power to most of the bike. The blue/yellow feeds power to the lighting.
Now this brown wire goes back to the fuse box and feeds power to the other three fuses.
It feeds the ignition fuse where it leaves the fuse on a red/white wire to the engine stop switch. There are several places along this power path that can lose the power, as before check every connection. The engine stop switch contacts can be dirty. It can be taken apart and cleaned.
From the engine stop switch the power flows to the ignition coils on a red/white wire. This red/white wire also feeds power to the safety relay and then to the starter relay, then out from this relay to the start button.
At the coils the red/white wire has a connector that accepts two wires. On the coils you a brown wire. The brown wires plug into the red/white wire.
At this point it may get a bit confusing because the diagram shows one coil has a orange wire and the other a grey wire. This didn't happen very often, both coils have orange wires. Now to wire the coils to the points so the plugs fire the right cylinders, the wire from the coil that fires the right side plug plugs into the wire going to the upper set of points. The left coil goes to the lower set of points.
As mentioned there are many places along this power flow that power can be lost. Following the power flow along this path and checking voltages at every connection you will find the weak spots.
Once you get every thing clean and tight the voltage on the red/white wire at the coils should be within about .2 or .3 of a volt of battery voltage.
Quite often the problem is dirty contacts in the switches. They can be taken apart and cleaned. Another common place is the fuse box. Glass fuses were crap 30 years ago and 30 years didn't improve them any. The metal clips that the fuses mount into were fine when new but 30 years didn't do them much good.
Even if the current flow didn't blow the fuse the constant heat from carrying the current will weaken the clips. The weakened clips won't hold the fuses tight and the heat increases, weaken the clips more, a vicious circle.
Replace the stock four fuse box with four inline fuse holders that use the modern blade type fuses that cars use. This will fix the fuse holder issue. Some don't like the four inline fuses and use a four place fuse box that uses the new blade fuses. Either way replace that old fuse box.
It is also a good idea to go through the whole wiring and checking each and every connection. Clean, tight, and a dab of dielectric grease to help thing stay clean. Even Vaseline, or plain grease can work.
Leo
