74 Ironhead will not fire

[Tattooo]

Can a meter tell me anything by doing this?

Yep it's the same thing, Well kinda....... But come from the battery.......

[mowen]

Can a meter tell me anything by doing this?

From battery points open 12.9
From battery points closed 0

[Tattooo]

From battery points open 12.9
From battery points closed 0

That's correct.......... Now we are getting some where.....

[TriNortchopz]

Not too much to it:

The contact breaker (points) ignition system

diagram of 1959-1978 Harley Davidson Sportster ignition system.
"...While the contact breaker is “closed” or connected to earth, current is flowing from the battery positive terminal to earth. The current flowing through the primary ignition coil sets up a magnetic field.

When the engine rotation reaches the proper place, the cam begins to rotate around and opens the breaker points, and the current flow from the battery to earth attempts to flow as the points gap opens.
When the current stops quickly, the magnetic field in set up by the primary coil collapses. The moving magnetic field induces a current in the secondary windings in the ignition coil. Since the secondary winding has a great many more windings than the primary, the induced voltage is very high, perhaps around 15,000 volts. The secondary coil is connected to the spark plug. This very high voltage is sufficient to make an arc jump across the spark plug gap.

https://krankengineering.com/tech/contact-breaker-points-ignition-system/

[Tattooo]

Now take your plug wires off and check the OHMs of the wire with your meter....... While we are doing it we might as well check everything....

[mowen]

Now take your plug wires off and check the OHMs of the wire with your meter....... While we are doing it we might as well check everything....

Not sure I know how to check the plug wires correctly

[TriNortchopz]

remove cap, one lead of multimeter on each end, set on lowest range, as the solid core wires should have close to zero resistance. Then check each cap; may have resistor caps, typically 5K ohms.

When checking voltage at points with points open, are you measuring the 'point' that moves, the open side of the points?

[mowen]

remove cap, one lead of multimeter on each end, set on lowest range, as the solid core wires should have close to zero resistance. Then check each cap; may have resistor caps, typically 5K ohms.

When checking voltage at points with points open, are you measuring the 'point' that moves, the open side of the points?

Have no readings on wires. Checked two different sets. Yes measuring points that move

[Tattooo]

Have no readings on wires. Checked two different sets. Yes measuring points that move

NONE when it's set on OMS????????

When you touch the two ends of the meter together what do you see???????

[TriNortchopz]

Could be your meter can't read that low (about 0.2 oms), a Rx1 scale would pick it up.
To check to make sure wire is not broken, try running 12 volts through it from your battery...touch one end of sparkplug wire to positive, check for 12 vols at other end of plug wire...with negative lead of your meter connected to the negative post of the battery.

[Tattooo]

Could be your meter can't read that low (about 0.2 oms), a Rx1 scale would pick it up.
To check to make sure wire is not broken, try running 12 volts through it from your battery...touch one end of sparkplug wire to positive, check for 12 vols at other end of plug wire...with negative lead of your meter connected to the negative post of the battery.

I've never had any problems with my meter getting a reading on plug wires if they are good, even if the wire is 5 ft long..........

[mowen]

NONE when it's set on OMS????????

When you touch the two ends of the meter together what do you see???????

00.1

[mowen]

Could be your meter can't read that low (about 0.2 oms), a Rx1 scale would pick it up.
To check to make sure wire is not broken, try running 12 volts through it from your battery...touch one end of sparkplug wire to positive, check for 12 vols at other end of plug wire...with negative lead of your meter connected to the negative post of the battery.

Nothing consistent with those readings. Using my new wires averaging about 3.5volts. Using an old set same. Idk

[farmall]

If the points are switching current correctly then I'd swap coil, wires and I always use new plugs just in case one or both old ones have issues under load.

Wires age and so do coils. I'd do both since any excuse to replace old electrical parts before failure is good, but I'd do the wires first, test, then swap the coil. (On points bikes I buy V8 solid wire kits and any plug or coil boots I need and solder the end connectors. Solids last a LONG time. "Carbon" wires are for RF suppression and aren't particularly durable.)

A meter will show continuity if one wire strand is good. Continuity is not ampacity. That's why USAF aircraft maintainers use "load lights" (bulb or bulbs in whatever socket is handy). When in doubt, swap parts to test, then shitcan what's bad and keep the leftovers.

If wiring harness is in doubt I hot wire straight to the coil input to provide known good input. If lead from to points is in doubt it takes minutes to make a jumper. Jumper leads are love. You can even hang jumper leads off a replacement ignition coil without bolting it to the motorcycle. Coils only "care" about power in and a switched ground. I expect both are fine since you have voltage at the points when they are open. If you had voltage with them in closed position that indicates a remaining open/incorrect connection.

This job should have taken about a half hour to troubleshoot since it's "hard broke" and not intermittent. Desire to not replace parts is fine, but should not conflict with having spares for troubleshooting and eventual use.

Overthinking points ignition troubleshooting tends to be a rabbit hole. If you had all the spares on hand you'd have been done long ago and if you have them in future your ass is covered. It's all win.

[JBinNC]

If the points are switching current correctly then I'd swap coil, wires and I always use new plugs just in case one or both old ones have issues under load.

Wires age and so do coils. I'd do both since any excuse to replace old electrical parts before failure is good, but I'd do the wires first, test, then swap the coil. (On points bikes I buy V8 solid wire kits and any plug or coil boots I need and solder the end connectors. Solids last a LONG time. "Carbon" wires are for RF suppression and aren't particularly durable.)

A meter will show continuity if one wire strand is good. Continuity is not ampacity. That's why USAF aircraft maintainers use "load lights" (bulb or bulbs in whatever socket is handy). When in doubt, swap parts to test, then shitcan what's bad and keep the leftovers.

If wiring harness is in doubt I hot wire straight to the coil input to provide known good input. If lead from to points is in doubt it takes minutes to make a jumper. Jumper leads are love. You can even hang jumper leads off a replacement ignition coil without bolting it to the motorcycle. Coils only "care" about power in and a switched ground. I expect both are fine since you have voltage at the points when they are open. If you had voltage with them in closed position that indicates a remaining open/incorrect connection.

This job should have taken about a half hour to troubleshoot since it's "hard broke" and not intermittent. Desire to not replace parts is fine, but should not conflict with having spares for troubleshooting and eventual use.

Overthinking points ignition troubleshooting tends to be a rabbit hole. If you had all the spares on hand you'd have been done long ago and if you have them in future your ass is covered. It's all win.

See my post #12, above.

Jim