LeMans IIIl Starter Relay

[MarkPell]

Good Friday Morning All!!
Starter has been acting and I assume it's the relay. Can one of you fine folks direct me where it is and if there's a generic replacement for it?
Mark

[Antietam Classic Cycle]

Right side, behind the rear master cylinder. A "cube" relay meant for fog lights or horns works fine. Available at just about any auto parts retailer.

[pete mcgee]

It may also be "startus interuptus".
Follow the wiring diagram  up through the start switch back down to the start relay where the guzzi bean counters mandated a 20mm long jumper from the relay coil power to the power in of the relay. This is then sent to the start solenoid on the starter motor, after about a 2.5m run of under sized wire, several molex connectors, several switches and a relay to power another relay.
While you are in there cut the loop off and run a 6mm square wire with a 30 amp fuse from the battery positive to the power input terminal of the start relay.
It took 32 years and 200,000 miles for this to happen to my mk3, but this fixed it.
Also moving the main fram earth from thr frame onto one of the battery tray bolts on the gearbox and cleaning up all the other earths in the system is an interesting day that will pay dividends in a bike the age of the mk 3.

[Kiwi_Roy]

It may also be "startus interuptus".-----------------------

As Pete says
https://www.thisoldtractor.com/guzzi007/schematics/1981_LeMans_III.gif

Leave the brown wire from Fuse 1 feeding the relay coil (85)  but take another wire direct from the battery through a 20 Amp fuse to the relay contact (87)
You might find the relay contacts 87 and 30 are swapped around, thats ok.
The relay solenoid is not a simple single coil as Guzzi show on their diagram, its two coils and they will draw over 50 Amps for a split second.
It's important to leave the Start relay coil on Fuse 1 so it's disabled when the key is off.
Here's a sketch, do this and you will be very pleased with the results.

Note: It won't crank any faster but it won't hang up, the solenoid will engage the pinion to the ring-gear with a resounding clunk, just the way it was designed to.

[MarkPell]

Thanks Charlie, Pete and Roy. I'll let you know how I make out!

[MarkPell]

Roy.
I got a new relay and plugged it in and no luck without doing added wiring as described. Here's how the wires were attached to relay with red on top, white on right (closest to battery) with browns on left and bottom. Nothing in middle.

Which pin is #87 on the relay that the added wire is attached to?

Thanks, Mark

[Kiwi_Roy]

it's a little hard to tell but the Brown wire goes to 85 and 87.
If you pull the brown wire off then connect it to just one of the terminals when you get it on the right one you will be able to make the relay click by pushing the start button Key turned on of course assuming fuse 1 is ok. So now the wire without a wire is 87, that's the one to liven direct from the battery.
Just to be sure everything else is ok you could take a wire from the connector 30 (shows as a red wire on the schematic) just poke it in and touch the other end to the battery (Make sure the bike is in NEUTRAL), the starter should spring into life. That exercise will show you the starter and battery are fine.

[Antietam Classic Cycle]

Here's a diagram I have, possibly from Patrick Hayes:





And this also:

Rewiring the small block starter relay.

The trick is in the brown wire.  It leads from the right handlebar to the relay socket under the side cover at connector 30/51.  From there, it is joined by a small brown jumper wire from connector 30/51 over to connector 86.  Disconnect the relay from the plastic relay socket.  Now look at the receiving side of the relay socket.  Each terminal has a slot with a small notch.  Reach into this notch with a small jewelers screwdriver.  Inside is a little tang on the female spade connector.  You need to flatten this tang so that you can pull the wire and spade connector out from the back of the relay socket.  We need to do this to swap the position of the two terminals within the relay socket.

Once you have both of the brown wire terminals removed from 30/51 and 86, then cut them apart as close as possible where they both join at the old 30/51 terminal.  Now, you have the wire from handlebar with a spade female on it and you have a short two inch wire with a spade female terminal.

Use your screwdriver to bend out and restore the little tang on the back of each female terminal so that it acts as a snap lock when you insert it back into the relay socket.  Now, reinsert the two terminals into the connector block BUT swap them so that the harness wire from the handlebar now goes directly into 86 and the short two inch wire goes into 30/51.

Now, manufacture a short red wire.  Perhaps 16ga and ten inches long with a ring terminal at the battery end, an in-line automotive fuse spliced into the middle and a straight crimp connector at the business end.  Splice this new jumper directly to the two inch brown wire dangling from the 30/51 position and install the ring terminal directly on your battery positive post.

You are all done.  Now, the 86 terminal only carries the load of the little relay electromagnet coil.  The 30/51 terminal (which gets energized when the relay closes) has a new, fat, short routing directly from the battery, throgh the relay contacts to the starter solenoid.  No more CLICK when you hit the starter button, just vrooooooom.

Patrick Hayes
Fremont CA

[Kiwi_Roy]

Yes Charlie, same as my sketch except it may have the power going the other way through the contacts.
I like to put the power to terminal 30 and take it from 87 to the solenoid (just as your diagram shows) because that's convention but Carl Alisons drawing showed the brown wire going to 87 with 30 going to the solenoid so I stuck with that, it makes no difference whatsoever.
What none of the Guzzi drawings show is the root cause of "Startus Interuptus" the second coil inside the solenoid that draws such a heavy current the switch and wiring cannot sustain it. The solenoid will draw over 50 Amps if its wired right but just for a split second while the slug is stroking then it drops down to 10.
All the Guzzi's I have laid eyes on have this second coil, you would think by now the factory would realize that and wise up. If you look at the spade terminal on the solenoid you can sometimes see the two wires soldered there.
Both coils have about 300 turns of wire but the one they don't show is actually 4 x as strong because it draws 4 x the current.
Nearly every explanation of how the solenoid works you read on-line is nonsense.

[MarkPell]

Well no success. No clicking of new solenoid, nothing doing the bypass with the red wire connector directly to the battery. Cleaned up the main ground and battery is fully charged.

[Kiwi_Roy]

Well no success. No clicking of new solenoid, nothing doing the bypass with the red wire connector directly to the battery. Cleaned up the main ground and battery is fully charged.

Try a hot wire from the spade terminal on the solenoid straight to the battery positive, just touch it on the terminal, you should see a pretty good spark and it should engage with a resounding clunk.
If that doesn't make it spin the starter needs an overhaul pull it apart or take it to a local starter repair place.
The old Bosch starters are very simple inside, really just brushes to go wrong, take pictures and we will walk you through it.

[Kiwi_Roy]

Well no success. No clicking of new solenoid, nothing doing the bypass with the red wire connector directly to the battery. Cleaned up the main ground and battery is fully charged.

You mean new relay? do you have 12 Volts on the brown wire? A bulb with a couple of wires attached will do to test it if you don't have a meter.
The relay only makes a quiet click noise, turn the music down so you can hear it. If you have a meter the relay coil will measure just under 100 Ohms. the pair of contacts will be open circuit.

[MarkPell]

You mean new relay? do you have 12 Volts on the brown wire? A bulb with a couple of wires attached will do to test it if you don't have a meter.
The relay only makes a quiet click noise, turn the music down so you can hear it. If you have a meter the relay coil will measure just under 100 Ohms. the pair of contacts will be open circuit.

Sorry, yes I meant relay. It was quiet in my shop so there was no audible sound. I'll check the voltage on the relay and do the solenoid to ther battery when I get home tonight and report back.

[Kiwi_Roy]

Mark, I sent you these in a PM
Some others might find them interesting as well
https://ibb.co/NrYw5Cn
https://ibb.co/Cw31tjs
https://ibb.co/9wMGxVq
https://ibb.co/4MRrfY9
https://ibb.co/CV9Lrvf

[Tom H]

If I'm reading right. The new relay is not clicking. Have you made sure that the starter button that you press is sending power to the relay?

Also as Kiwi said, do try the old wire from the positive battery terminal to the spade connector on the starter solenoid trick. At least that will confirm the starter is working.

Tom

[Kiwi_Roy]

Looking at Mark's profile
2000 Kawasaki W650
1983 Lemans III
2019 Road Glide
2006 FJR1300
2007 Rokon Scout
1971 Bultaco Alpina
1971 Rupp Roadster
2006 Aprilia Mojito 150
2010 Vespa 150
we see a wide range of motorcycles, most of these will have permanently engaged starter motors with a sprague clutch They just have a high current relay to make them spin then we have one old Lemans III with an antiquated starter that requires a beefy solenoid to throw the starting gear into mesh, its not surprising that he was having a hard time figuring it out. I'm fairly sure the grease in the ignition switch has gone hard over the years causing a little bit too much resistance so that the solenoid is barely able to do what it's designed to do.
In a case like this what to do, walk him through cleaning the ignition switch, perhaps that would have got it spinning again or perhaps there are some other high resistance joints, connectors, loose spade connectors, fuse clips or do we talk him into wiring the starter as it should have been done in the factory?
I tend to go for the latter.

It's a real pity that Guzzi owners are put through this grief when anyone with electrical experience can see the factory just don't get it. Im sure any of the starter manufactures could point out the error of their design, if a simple sparky can see what's wrong what's wrong with their electrical engineers?

Last I heard Mark has the starter doing its thing again and is looking forward to a rally.

[Antietam Classic Cycle]

After the first few Loops (V700 and early Ambos that didn't even have a starter relay), Guzzi wired the circuit correctly. Most Ambos and all Eldos had power fed to the relay directly from the battery. Like most things that changed for the worse after that, I blame De Tomaso's "penny pinching" ways for the Tonti wiring deficiencies. 

[pete mcgee]

So Mark,
How goes the war?

[Missionguzzi]

All, I read through the above chain (now 5 years old) as I'm trying to find an EASY way to pull out the starter relay and check it on a LM III.  The thing is buried under and behind the rear brake master cylinder and all the rest of the stuff under the right side cover (fuse box, rectifier, etc) and even with the battery out I can see no easy way to get to it to check and remove.  Am I missing something?  Is there a trick to it?  Your help will be much appreciated.

[Antietam Classic Cycle]

All, I read through the above chain (now 5 years old) as I'm trying to find an EASY way to pull out the starter relay and check it on a LM III.  The thing is buried under and behind the rear brake master cylinder and all the rest of the stuff under the right side cover (fuse box, rectifier, etc) and even with the battery out I can see no easy way to get to it to check and remove.  Am I missing something?  Is there a trick to it?  Your help will be much appreciated.

Remove the battery and rubber tray. Using a deep-well 10 mm socket and ratchet, remove the "prong" that the bottom of the side cover slips onto. There's a nut on the inner end, use a 10 mm wrench to hold it. The bracket holding the relay and the relay should come out from under the master cylinder now.

[guzzisteve]

I hope he doesn't want a video, too bad my LM3 is stripped of it's loom. Fun

[Missionguzzi]

THANKS!  No need for a video.....    It's not visible enough even with the battery and tray out to see if that's all that holds the relay in place.  Should be relatively quick and easy, I hope.   I even have a spare relay (if that is actually the issue).

[guzzisteve]

If it's original it'll be kind of clear or foggy plastic, you'll have a replacement on the bright flash circuit. Same relay.

[Missionguzzi]

This relay wasn't the clear plastic Marelli type, but a rather large metal canister.   I tested it and it was good.  Then I tested my cube relay, and it was good.  Neither worked in the circuit.   I did some point-to-point continuity testing and found mis-wired connections up under the fairing, and fixed them.  Now it's good.  Thanks for the tips!