Starter VS solenoid: current draw

[LoRydr]

I disconnected all wires from the solenoid...hooked a separate battery to the smallest & largest terminals, and got proper movement of the bendix over the ring gear. I also measured ohms at all points/terminals and the measurements were proper.

So the pull in coil works nice. Just because the ohm readings are good for the hold in coil, how can one tell if it is working? If I had neg batt to the case also, would the hold in coil still operate if I unhooked at the starter terminal?

When all wires are hooked up, the starter takes too much current away from the solenoid, causing it to let loose partially, and not letting the bendix engage the ring gear.

[Lew]

I don't understand what you mean when describing pull in coil and hold in coil.  The solenoid has one coil, that when energized pulls the slug into the magnetic field and the starter clutch (bendix) into the ring gear while simultaneously switching on the starter through internal contacts.
If you are referring to the starter relay as the hold in coil, then it can be checked for continuity between contacts 85 and 86 (coil) and contacts 87 and 30 (when energized).
In normal operation the case of the solenoid is tied to negative.
The starter relay should operate whenever the ignition switch is on and the start switch is pushed regardless if the solenoid is connected to it or not.
It's possible the contacts in the starter relay are corroded or burned (terminals 87 & 30), which would cause inconsistent voltage to the solenoid and allowing it to drop out or chatter.
It's possible the battery has insufficient current to energize the relay, solenoid and starter.
It's possible there is low voltage at the starter relay either from a defective battery, defective start switch, or faulty wiring.
It's possible the starter is defective and pulling excessive current from the battery causing the solenoid to drop out.
It's unlikely the internal contacts for the starter (in the solenoid) are bad as the solenoid would still energize.
It is also possible to have an intermittent break in the solenoid coil windings, that can open under a current load, de-energising it and dropping out the starter clutch (bendix).     
The problem you're describing is usually the result of a bad battery or corroded battery cable connections.

Lew

[LoRydr]

The pull in coil between the skinny terminal and the (to) starter terminal stud, measures .3 ohms. The hold in coil between the skinny terminal and case ground measures .6 ohms just like the manual suggests. I've tried attach a pic of the diagram.

I did pull the battery and found a messed up neg post. I'll have to grind & sand it back to usable. Then I'll get a load test or two.

[Lew]

OK, I see what you are referring to.  It's actually one tapped coil, that is backfed from the battery at the time the starter motor is energized.  It's to overcome the voltage/current drop at the starter relay due to the high current draw of the starter motor.
This is why it's important to connect the battery and starter leads correctly at the solenoid.  If connected backwards the starter can possibly stay engaged due the solenoid still being energized through the starter contacts.

[LoRydr]

That explains a lot. Backfed through both parts of the whole coil to case ground, assuming not enough current at the tap? I use a large napa/ford style relay to send power to the battery stud with a jumper copper plate direct to the coil tap terminal at the same instant. Similar effect to ones that use a springy feeler gauge to make manual contact. Saying that...max current is present to both terminals as long as I hold the button. Maybe my hold in coil gets nulled out with the same juice at each end of it.

But the pull in coil should have the same effect I guess. Really I might not want that jumper. I might want that skinny terminal to have no battery potential at all after the solenoid operates. Am I on the right track?

I'm sure, to avoid a run on starter, the tap/skinny terminal still has to have some control. Although the large napa relay won't let that happen.

[LoRydr]

The spacer does not belong in the solenoid plunger on my bike. Once removed, it works nice.

[Lew]

The spacer was required on some of the early rear belt drive models to provide enough throw for the yolk to engage the ring gear.  The moco soon reverted to a specific yolk (31300-80A) for those models to eliminate the spacer.