GRiSO Startus Interuptus

I agree with Dave - high resistance in the -ve lead will cause problems you see.

Some of us have moved the main earth from the original location, to one of the bolts at the top of the clutch housing. The original stud was ordinary, at best - in fact it may be loose. This will also affect the chargeability of you battery. Check it all out at the main earth point.

I have also changed my main earth cable as I wasn't happy with the original.

All this confirms the theory of "'talian 'lectrics"

If I said the factory are clueless about electrickery you might say I'm being harsh

After fully charging the battery overnight and testing the battery voltage under load today (while trying to start) I’ve come to the conclusion the battery is gone (last week when I did the same it seemed fine oddly enough). It dropped from 12.74V to 12.4V with the key on, then it dipped to 9V on the first start attempt (failed to start) and 7V on subsequent start attempts.
Will buy a new battery and then test the bike’s charging system to see if I can find a reason why its eating batteries. Could be bad luck of course.

One more question and then you are rid of me ^^ Would a broken battery also explain the high number of 0.8V measured between battery negative and engine when trying to start or is it likely to be a separate issue? I visually inspected the cable and mounting points and they looked clean.

Thanks Roy for the comprehensive reply. I’ve ordered a new battery, this time a Lithium. Looking at the ground above the starter motor, the ground itself and the wires looked in good shape. At the ground point above the starter motor, 2 wires are connected: a very short wire coming out of the wiring loom behind the starter motor, as well as a second wire which goes in the direction of the airbox. See photo:
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However I can’t see an obvious ‘better’ reachable ground point the wires could be connected to, to see if that makes a difference.

Just above on the clutch housing there are several bolts that could do the job. You will have to enlarge the lugs to fit on the larger bolts.

Oz1200Guzzi wrote:

Just above on the clutch housing there are several bolts that could do the job. You will have to enlarge the lugs to fit on the larger bolts.

Thanks, I didn't think of that. Do both ground wires need to be connected to the same ground point? As the short wire from the loom will not be able to reach those bolts unless I start messing about with the wiring loom where it protrudes from.

I think while I'm busy I may as well just replace the negative wire from the battery by a new one that is also slightly longer so I have a bit more play with it. I assume its just a straight swap, i.e. the negative cable doesn't split somewhere in the wiring loom, it just goes directly from the negative terminal on the battery to the ground point?

Yes both wires on the same point. Feel free to replace the -ve lead - I replaced mine with "light gauge" welding cable which has a decent cross-sectional area (csa). The -ve lead is a direct point-to-point cable.

Thanks for your help Tony!

Kiwi_Roy wrote:

motor-timothy wrote:

After fully charging the battery overnight and testing the battery voltage under load today (while trying to start) I’ve come to the conclusion the battery is gone (last week when I did the same it seemed fine oddly enough). It dropped from 12.74V to 12.4V with the key on, then it dipped to 9V on the first start attempt (failed to start) and 7V on subsequent start attempts.
Will buy a new battery and then test the bike’s charging system to see if I can find a reason why its eating batteries. Could be bad luck of course.

One more question and then you are rid of me ^^ Would a broken battery also explain the high number of 0.8V measured between battery negative and engine when trying to start or is it likely to be a separate issue? I visually inspected the cable and mounting points and they looked clean.

No, for there to be a high Voltage between battery Negative and ground the battery ground is loose, it may not look like it but sometimes there is corrosion on the battery terminal or where the battery strap touches the chassis. Battery terminals especially can develop a lead oxide layer sort of a dark grey material that's a perfect insulator, I have seen batteries bolted tight with no connection at all.  You can demonstrate this oxide layer if you take your multimeter and just rest the multimeter probes on the lead terminals, you get no Voltage reading until you jab the sharp points through the oxide layer.
As an apprentice I learnt to scrape the lead terminals clean and then smear them with Petroleum Jelly AKA Vaseline, this protects the lead from Oxygen, If you don't have Oxygen you can't get Lead Oxide.
Its very easy to miss the Voltage drop, if there is no current flowing there are several connections in series where it could be lost.
If you just measure the positive terminal to chassis what can happen is the current can push the negative terminal down below ground potential for example
the positive terminal is reading +10 to chassis, the negative might be reading -2 to chassis  so the starter only sees 10 Volts because it operates between battery + and chassis.
The best time to read the various Voltages is while the motor is trying to crank, the current is heavy so any resistance shows as Voltage drop.

My last resort was to replace both battery cables and this solved the damn problem and now I'm happily back riding the Italian Stallion. Thanks for the help Kiwi_Roy.

Shout out to Kiwi-Roy! He's mentioned on YouTube!

Martin Arundel in the UK was having problems with his Cafe racer GRiSO not always starting. The starter fuse wasn't the problem. He replaced the 12 year old battery, and serviced the starter motor but the bike would not start consistently.
Alas, he perused the 'Ghetto' and he came across the startus interuptus thread and followed Kiwi-Roy's advice to replace the 'starter relay to solenoid wire' with something more substantial. He posted a lengthy video on YT about a week ago. He's a happy camper now.

Can you post the link?

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Hope I did this right.

That works. Unfortunately, I don't have the patience right now to sit through the whole thing.

It is a lengthy video. It should have been about 10-15 minutes. Maybe others would appreciate the whole thing.

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I watched through Martin aka Grisocaferacer's video from start to finish, I was really interested to see what he found, sure it could have been a bit shorter but he's an electrical Engineer used to not cutting corners, the video is excellent IMHO it shows a lot of information that most would just skip over.
I was a bit surprised to see how strongly the solenoid seemed to pull in without spinning over, not just the quiet click of the relay.
From the way the headlight dimmed it was obvious a lot of current was going somewhere, I suspect the Voltage remaining at the headlight and the solenoid is only about 6 Volts.
On this particular bike the headlight is indirectly powered from fuse 2, the same weak yellow wire that feeds the start relay, this worked in our favour indicating the Voltage loss at the start relay.
When the solenoid pulls in and the main contact doesn't close both solenoid coils remain in circuit drawing 20-25 Amps, this is what blows the 15 Amp fuses sometimes.
With the weak relay supply the solenoid is closing very slowly, I suggest the main contact is not quite closing, that's why there is no rotation.
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Now with the new direct feed to the start relay and decent size wire the solenoid inrush current will be about 50 Amps providing 100% strength throwing the gear into place slamming the main contact closed then it drops back to 10 Amps while the motor cranks. A 20 Amp fuse is more appropriate for these new operating conditions.
The Motor itself will be drawing 150 - 200 Amps while cranking, there is no change there.
Testing the motor on the bench at minute 24 notice how positive the solenoid works when he trigged it with needle nose pliers, see the big spark when he makes contact with the trigger terminal (40 odd Amps). The low speed of the motor is because of Voltage drop in the long jumper leads and perhaps a weak original battery.
The video (minute 46) shows the wimpy relay to solenoid wire on the 8 Valve just as it is on the 1100 4 Valve. That little bitty wire would like to carry 40 Amps, what hope of that?
.........
Thanks for the video Martin, its given me additional information I will be able to pass on to other Guzzi owners.
BTW
I don't believe the headlight comes on with the normal CARC wiring until the motor is running but you will get the same Voltage information by looking at the numberplate light
Martins GRiSO has an after market headlight wired differently so it picks up Voltage from the same fuse as the start relay, it shows how weak the supply is.
Do as he did with a new fused feed to the relay and beefier wire from relay to solenoid and never look back.

Thanks for posting all of this info - KiwiRoy, especially.  Startus-Interuptus reappeared on my 2012 8V last fall, and I'd like to do the heavier gauge wire mod between the starter relay and the solenoid.  (I already have the MPH kit running from the battery, which "cured" the problem several years ago - but now it's doing it's thing again..)

I just want to make extra certain that I'm understanding correctly:  the thin gauge oem wire from the relay to the solenoid doesn't need to be removed altogether (as it's part of the wiring loom), just disconnected at both ends, insulated, and tucked away to prevent any chance of a short.  I then run my new, heavier gauge (18 awg or better) wire between the relay and starter solenoid, re-connect the battery, and with a little luck Bob is my uncle (so to speak).

Please let me know if this sounds right.  I'm trying to take the "measure twice, cut once" approach, and understanding electrical circuits has never been my strong suit.

Thanks

No you can cut it about 3" long at the relay end then solder or crimp it to the new larger wire running to the solenoid, the old wire at the solenoid can be tucked away or cut off.
I'm not 100% sure what the MPH kit does on the GRiSO, I assume it just runs a new power feed to a new relay socket that plugs into the old one.
You could perhaps run that MPH feed directly to the OEM relay (a yellow wire I think)

Thanks for such a quick reply, Roy.  

Re: the MPH kit, yes, that's exactly what it does - with a 15A fuse in the line.  (Though, I've heard that a 20A is still safe, and more reliable.  I'll probably switch it.)

So, if I'm understanding correctly, the 3" of thin OEM wire that the current would still have travel through isn't enough to cause an issue, but connecting the heavier gauge wire this way is much easier than fiddling around with the connection inside the relay?

Thanks again..

Yes exactly

Kiwi_Roy wrote:

Yes exactly

Perfect - thanks again, Roy.

Running around with a pocket full of fuses, and wondering whether my bike will start several hundred miles from home has been a bit of a bummer. Hoping that this will sort it.

Yes, a 15 Amp fuse is too small, use a 20
The inrush current with improved wiring will be something like 40 - 50 Amps but just for a few milliseconds.

Frank,
I have the MPH kit and used the 15 amp fuse that came with it for maybe a year before it blew one day. It did it again not too long after. Someone here (probably Pete or Roy) advised me to go to a 20 amp and that’s worked well, not to say that maybe once a year or longer it will also blow, so load a couple of spares in your tool kit.

JohnA wrote:

Frank,
I have the MPH kit and used the 15 amp fuse that came with it for maybe a year before it blew one day. It did it again not too long after. Someone here (probably Pete or Roy) advised me to go to a 20 amp and that’s worked well, not to say that maybe once a year or longer it will also blow, so load a couple of spares in your tool kit.

Thanks, John - yes, definitely going to switch it to a 20A. Hopefully, once I get the new wire installed it'll be less likely to blow either way.
Been keeping spares in my toolkit for a long time now, though - just in case. It IS Italian after all...