Startus Interuptus, Help Me Understand It. Updated ?'s

[wirespokes]

I'd never heard of this problem before and have been around older airheads and a few oilheads since 1990. Evidently the airhead starter circuit isn't as bogged down by resistance. The 76 airhead wiring diagram I just looked at does show the two solenoid coils, but diagrams after that don't show starter internals, just connections. So it appears they knew about it. No fuse on the lead to the starter relay, no extra connections.

This comes back to my conclusion that electrical systems are the most difficult for people to understand.

[Idontwantapickle]

My take on the problem is the factory don't understand the starter solenoid, look at any Guzzi diagram, it only shows one coil.

~~~~

Conclusion
I'm not sure what it will take for the factory to wise up and fix Startus Interrupts but I can see by comparing schematics they have been thrashing around in the dark adding extra relays. it's such a simple problem once you understand it's caused by too little current or inversely too much resistance.

Roy,

It's not that the designers don't understand the circuit. It's that their lawyers do understand people. We've covered it before but the seemingly idiotic power circuit to the solenoid is simply to provide a failsafe for circuit interruption if something goes wrong. By turning off the key all power is cut. Mostly.
When we add together the factors of complicated circuit, small wire size, irregular vehicle usage, dodgy AGM battery life, a constant small drain from ECU, and age we get..........CLICK. .....dammit!!!

I really appreciate that you took the time to put a scope on it and give it some thought. If more people were like you and less worried about lawsuits then we'd be better off. At least on this issue!
Most people overthink it. The fix is easy.
 

Hunter

[Tom H]

I think I understand it a bit better now, at least as far as Tonti FI models go. Even though I do not have a problem at this time, I think I will apply a fix shortly.

Thank you all again for your wisdom as patience!!
Tom

[Kiwi_Roy]

Roy,

It's not that the designers don't understand the circuit. It's that their lawyers do understand people. We've covered it before but the seemingly idiotic power circuit to the solenoid is simply to provide a failsafe for circuit interruption if something goes wrong. By turning off the key all power is cut. Mostly.
When we add together the factors of complicated circuit, small wire size, irregular vehicle usage, dodgy AGM battery life, a constant small drain from ECU, and age we get..........CLICK. .....dammit!!!

I really appreciate that you took the time to put a scope on it and give it some thought. If more people were like you and less worried about lawsuits then we'd be better off. At least on this issue!
Most people overthink it. The fix is easy.
 

Hunter

Hunter, I'm not sure I agree with that, both my 2001 VII Sport and 2007 Griso was wired with a fuse direct from the battery, if you turn the key off the relay will drop out, that's what relays are for, to interface between high and low current or high and low Voltage circuits. Sure running the current through the switch provides a more direct isolation but its also more dangerous IMHO.
As long as the Start relay coil is switched by the ignition the relay will protect the circuit.
http://www.thisoldtractor.com/guzzi007/schematics/1999_V11_sport.gif     Fuse 5
http://www.thisoldtractor.com/guzzi007/schematics/2006_Griso_1100.gif   Fuse C
Both fuses are fed direct from the battery.
If it were just the lawyers they would be consistent don't you think?
And that would not explain why they don't draw the solenoid properly.
I also think they may measure the current the solenoid draws and size the wiring accordingly, all they would see is the 10 Amps of the Hold in Coil, the pulse of high current is too short for a meter to register, that's the reason I used my scope.
I can't find anything that tells me the rating of the ignition switch but I doubt it's 50 Amps
The Omron Normally Open relay contacts are rated at 100 Amps inrush, (the Normally closed are 60 Amps)
https://omronfs.omron.com/en_US/ecb/products/pdf/en-g8hn.pdf
All the bikes the factory work on are pristine, they don't see the bike 10 years down the road.

Here is another sketch I did for an owner. I suggested #16 AWG wire.


When you put your finger on Start Button the relay closes and current passes forward in both coils, the coils work together to pull in the solenoid. (30 - 50 Amps)

Once the main solenoid contacts close (15 - 20 milliseconds later) the Grunt Coil is bypassed and just the Hold in coil keeps it in place (10 Amps)

When you take your finger off the button the coils don't let go instantly, the main solenoid contacts are still closed but now the two coils are in series.
the current goes backwards through the heavy coil and forwards through the lighter coil. Because both coils have the same number of turns they cancel each other out so the solenoid is let go, the contacts open and the solenoid springs back to its home position (0 Amps)

[Chuck in Indiana]

^^^^^^
Just added to my "Roy's Guzzi Stuff" file. Thanks again..

[dguzzi]

Next question,  best (easy) way to identify the relay?  Maybe different for different models?   I'll do this before I ever have a problem!

[Kiwi_Roy]

Next question,  best (easy) way to identify the relay?  Maybe different for different models?   I'll do this before I ever have a problem!

Good Idea, heres how I do it
I look up the appropriate Carl Allison Drawing http://www.thisoldtractor.com/guzzi007/sportissimo.html
The Start relay is always wired to the starter solenoid. Of course this doesn't tell me the physical location
Examples
http://www.thisoldtractor.com/guzzi007/schematics/1971_V7_Sport.gif  Look how simple this old V7 is, I bet it never suffered, it doesn't even have a fuse
http://www.thisoldtractor.com/guzzi007/schematics/1978_LeMans_II.gif This old girl was probably an early sufferer (fuse 1 is powered from ignition) but easily fixed. Note the starter solenoid is not drawn correctly
http://www.thisoldtractor.com/guzzi007/schematics/2000_Bassa.gif  I can tell this bike will have trouble with the fuse fed via the ignition switch, I doubt it lasted much more than 10 years.
http://www.thisoldtractor.com/guzzi007/schematics/2005_Breva_1100.gif The Brevas were an early sufferer with the relay 3 fuse fed from the switch, easy solution. Power relay directly from battery.
It's quite easy to identify the relays in the later bikes by the wire colours.

Earlier bikes
If you were to pull the relays out and measure Ohms between the 87 terminal and chassis it would measure like a dead short but the headlight relay would be similar.
Then you can unplug the spade connector at the solenoid, it will go from a short to open.
Perhaps take a test lamp and plug into the coil terminals with the key on the lamp would light when you press start.
It's also possible to short the output terminals in the relay socket with a jumper 30-87 or 3-5 the starter will engage so be careful and make sure the bike is in neutral, pull in the clutch lever just to be safe.

[wirespokes]

Can't you just listen, or feel with a finger pressed to the relay, for the click?

[Kiwi_Roy]

Can't you just listen, or feel with a finger pressed to the relay, for the click?

Of course but some bikes have the relays so close to each other, I'm thinking of the spine frames or EV/Jackal
There is also a lot of noise from the starter gear

[chuck peterson]

Roy's diagram was applied to my 1990 Cali and it transformed my universe....errrrrr r, bike. Spun over before I could finish pushing the button, so to speak. Prior to that I would carry a short fat wire and a pair of insulated pliers to send sparks to the starter after pushing the button 5-20 times...click...cli ck...click. Fun to do at bike night..

[bad Chad]

 I’m so glad I didn’t have to hack into the wiring myself even with Emeril’s help I don’t know what would’ve happened ?    I contacted Mike Haven at MPH Cycles, and for less than the cost to fill up my suv he sent me a pre wired plug and go fix!  I couldn’t be more pleased with him or his fix it kit.

[kingoffleece]

I have the MPH solution on my Norge.  All good.
The wizards at Hamlin Cycle helped me with my 2001 Jackal.   The bypass was done as described above-direct fused and all that, and two additional grounds were added.  None of this was difficult to do but a bit time consuming as it's all wrapped, tucked away nicely, and invisible when looking at the bike.  The idea was to eliminate the starter switch form any duty onter than telling the relay (new) to start the motorcycle.  Works a treat.

[Idontwantapickle]

Hunter, I'm not sure I agree with that, both my 2001 VII Sport and 2007 Griso was wired with a fuse direct from the battery, if you turn the key off the relay will drop out, that's what relays are for, to interface between high and low current or high and low Voltage circuits. Sure running the current through the switch provides a more direct isolation but its also more dangerous IMHO.

I agree. If it has a relay why does the high current for the device still go through the relatively small contacts and wiring of the key switch?
Other similar devices that I service have redundancy to protect the user and the equipment from harm if things go wrong. It's done for liability protection. Guzzi just didn't do it very well!

Hunter

[mphcycles]

Hi Wayne, yes even still after all these years I am still making the plug and play kits. I even took one with me on a visit to the factory,offered it to them as a gift to send out to all dealers. Of course they had never heard of Startus Interruptus, a name coined by Todd Haven. So here we are, my kit is just an easy way for those to solve the issue  for people who are not comfy with modifying any wiring.
The very first Breva 1100 in the USA did it to me on a photo shoot ride, some time with a meter revealed the problem. There is insufficient current at the term 30 of the start relay, the voltage drop under cranking would often measure over 6 volts lost from the battery to the relay. So there isnt enough juice to make the starter solenoid engage.

[Kiwi_Roy]

Thanks for that Mike.

It doesn't surprise me that the factory denied all knowledge of Startus Interruptus but I see evidence they have tried to solve it by adding relays and such.
I maintain they don't know how much current the solenoid draws because they never show the heavy current 2nd coil and it's too fast to measure on a working starter.

You measured Voltage Drop, I measured Amps, same thing really.

Roy