Starter, Solenoid, and Starter Relay

Troubleshooting

Sometimes pushing the start button results in clicks, and the starter does not turn the engine. There are a number of things you can try when this occurs:

1. First off, give the solenoid a good rap with a rubber mallet. It may be that things are just a little bound up and the rap may be all that's needed. Growing up, we had a lawn mower that required this treatment...it worked for years!
2. Check all of your connections to be sure that they are making good contact.
3. Since a clicking sound is heard, the starter button is most likely fine. The starter wouldn't be making any sounds if the button weren't making the connection.
4. It may be that the battery is discharged and not supplying sufficient power. If you have a charger, you can charge it and see if that makes a difference. Alternatively, you could use jumper cables from a running automobile to provide sufficient juice.
5. If the starter still clicks when you know you have sufficient battery power, then it's time to determine whether or not the starter is bad by bypassing the starter relay and the solenoid with a pliers or a screwdriver or something to make the connection...Here's how:
   1. Remove the small wire from the solenoid (the one that attaches with a spade connector). Leave the big wire connected.
   2. Use a pliers/screwdriver/etc to connect the big bolt to the small spade connector.
   3. Make sure the key is on, and the starter should rotate when contact is made...there will be some sparks when you make the connection, but that is normal for this procedure.
6. Now, if the starter rotates and you know that you have a good battery and starter button, then only one of two things can be the culprit: either the solenoid is bad or the starter relay is bad.
7. Start with the relay. My original relay went bad and was replaced with a generic relay. It looks different from the original and won't mount the same, but works great.
8. If that doesn't fix the problem (at least you now have a cheap spare), it is time to address the solenoid (which is a more expensive replacement part). I don't see any harm in taking the solenoid apart and cleaning things up, that may correct the problem.
9. If cleaning things up doesn't fix the problem, get a new solenoid.

How to bench test the starter and solenoid

I extracted this information from Bruce Giller off of the old Topica Loopframe_Guzzi news group (which has now moved to Groups.io). In Bruce's own words:

You can bench test the starter off the bike. Clamp it in a vise for there is no point in trying to hold it with your hands; lots of torque. Get a well-charged battery and some jumper cables. Clip the negative to the body of the starter.

Test the solenoid: apply the positive cable to small wire connection (usually a spade type) on the solenoid; you are playing the part of the starter switch. The solenoid should click loudly and throw the ring teeth engagement gear out into the nose of the starter. The starter should not turn.

Test the starter: now apply the positive cable to the big nut on the solenoid that was NOT used for the battery cable on the bike. Here you are bypassing the solenoids' internal T-bar electrical connector and feeding current directly to the starter. The starter should whir confidently but the ring teeth engagement gear should not budge.

If both components work independently, you can bench test the starter as a whole. Clip the positive cable to where the bikes' battery cable used to attach (big nut). Get a small jumper wire and attach one end to the positive cable and the other to the solenoid connection. Now the solenoid should kick out the engagement gear AND the starter should turn.

How the starter works and more troubleshooting

I extracted this information from Patrick Hayes off of the old Topica Loopframe_Guzzi news group (which has now moved to Groups.io). In Patrick's own words:

Look at how the system operates. It must be a clear, two-step process. When you hit the button, the relay and then the solenoid get energized. The solenoid pulls its core inward, which pushes the starter gear forward through a pivot lever. The starter motor is not yet energized and does not yet spin.

As the pinion gear moves forward, the forward edge of its teeth are supposed to impact against the rear edge of the ring gear teeth. Both sets of teeth should be angled or tapered in some way to discourage a direct, face-to-face tooth hit. At the point of impact, the pinion should be forced to rock one way or the other to slide between mating ring gear teeth.

As the teeth fully mesh and engage, the huge contacts down at the back end of the solenoid inside its cap come into play. When these contacts hit, the starter windings themselves become energized and the motor starts to spin.

So, you have one of two problems if the starter does not always cleanly engage the ring gear.

First, is there some reason that the gear teeth do not embed? Has this error caused the teeth to grind against each other, square off, and exacerbate face-to-face locking? Can you get at the damaged teeth with a dremel grinder and restore a pointed face condition?

Second, is the starter being energized to spin before the gears are meshed? And here again we have two potential problems. Somehow the starter is getting juice before the gears are meshed.

First, has there been enough wear to the pivot and the various mechanical points of the lever system so that it is not pushing the pinion gear as far forward as it used to? Not sure how to repair that, but you could remove the lever and have a little weld dab added to it to restore original thrust dimension.

Second, has someone repaired, cleaned or replaced this solenoid? Was an alternate substitute solenoid used? If it is the original solenoid, and it was cleaned or repaired, was the original cap gasket saved or reproduced? The physical position of the solenoid rear cap (and thus its internal contacts) are critical to the design of this system. If you move the cap slightly forward (by omitting the cap gasket) you allow the starter contacts to come into play before the plunger thrust is complete. If you use an alternate solenoid, the dimensions for thrust and contact may not be completely accurate.

I would suggest a thorough tooth inspection and some lubrication of the pinion shaft to get the gear sliding easier. You can run the solenoid repeatedly on the floor with some test wire and observe its action. Just be sure to disconnect the heavy starter lead so you don't energize that spin or the motor will jump all over the place.

I would suggest a removal and very thorough inspection of the pivot system and the fork face of the pivot against the pinion gear. Is there some substantial wear and can it be improved or corrected?

I would suggest disassembly of the solenoid and the addition of a double or triple thick gasket between the end cap and the solenoid body. By adding gasket thickness here, you are moving the motor contacts aft and delaying the instant point of energizing the starter. The plunger has to go deeper before it makes the motor spin. Perhaps by stacking gaskets, you can delay it long enough to get deeper tooth penetration before spin. At any rate, what you have now is a rotary grinder and you are damaging the face of the pinion and ring teeth. By doing so, you are making the gear contact position worse as it respects the internal solenoid contact position. You have to get tooth penetration BEFORE spin. Doing the gasket stack might be enough to counteract the tooth wear already in place.

One last thought. You might ignore ALL of the above and just inspect the wiring at the starter and solenoid. You maybe haven't done something to short this wiring in some way, or hooked it up incorrectly so that the thrust action and the spin action are happening simultaneously? That would be a case for failure for sure. You have to separate these two functions in time and space. The starter relay ONLY energizes the solenoid. It is the action of the solenoid which energizes the starter windings. I'm trying to imagine how you could hook up contacts incorrectly to get the motor spinning by the relay circuit rather than by the solenoid circuit. Could happen I suppose.

Also, the floating contact on the back end of the solenoid plunger should be a spring loaded bar. Might be possible to lift that bar against its spring and insert something like an O-ring or split washer onto the stem which would effectively move this floating contact forward and thus require a deeper solenoid core penetration before starter contact. This would then require deeper penetration of the pinion/ring pair before spin. There is no spin action here and not all that much heat, so an O-ring might give you the adjustment you seek.