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Jim Mac View Drop Down
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    Posted: 16 Mar 2016 at 13:32
By Brian UK

More or less all models of Guzzi may suffer from this at some time in their lives. You push the starter button only to hear a small click, and nothing else happens.

It is mainly due to the strange wiring used, where the high current which is required to operate the starter solenoid has to pass through the ignition switch contacts, which are rarely designed for this.

The cure is to do a small modification to the wiring of the start relay, found amongst the relays on all models.

In essence you need to remove the wire connected to pin 87 on the relay, ensuring that the loop to pin 85 remains intact and still connected to the loom. Then run a new wire from battery positive via an inline fuse of at least 15A back to pin 87 on the start relay.

 

 

 

The same problem also seems to surface on the new 750s and CARC models. However different relays are used so the numbers above don't work.

On the new models this picture explains what to do.

Remove yellow wire from pin 3 and tape it up. Then add new connection from pin 3 to battery positive via a fuse.

One advantage to doing this is that the yellow wire you remove could be used as a switched power source for any accessory.

This mod also bypasses the fuse which sometimes blows when hitting the start button.

Beware, this mod alone will not work on some of the later cali models - post '93 - where the headlight is switched off when the starter is pressed.
On these you would also have to remove the lights relay and bridge across what would have been the relay contacts, otherwise the relay is energised all the time and will discharge the battery.


Edited by Brian UK - 13 Nov 2014 at 23:25


Edited by Brian UK - 03 Apr 2016 at 08:30
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Motoguzzler View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Motoguzzler Quote  Post ReplyReply Direct Link To This Post Posted: 27 Jul 2016 at 15:06
I used a jewelry ultrasonic cleaner with a mix of vinegar and water to clean all of the connectors and switches on the bike - 1983 Le Mans III.  This visibly got rid of the oxidation and tarnish on contact surfaces thereby reducing contact resistance.  This may be the underlying reason for the issues on the starter circuit as, realistically, the starter relay does not require a large current to operate and is designed to not load the small contacts on the starter button.  Starter relays are inexpensive and are a stock auto store item so not worth cleaning as such and their contacts do arc with the back emf of the solenoid coil causing contact erosion so have a definite "lifetime".  The spade terminals on the relay do suffer badly with oxidation over time too.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 27 Jul 2016 at 21:20
If it only happened on older bikes I might agree, but as it also happens on many of the new range... It's. Not the current taken by the relay, it's. The current taken by the starter solenoid which can easily be 20 Amps.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Motoguzzler Quote  Post ReplyReply Direct Link To This Post Posted: 27 Jul 2016 at 22:13
Sorry Brian, have to disagree.  A 30A rated relay, FIAMM, in the photo is the current rating of the contacts not the coil closing current.  I measured the current as 170mA using a motorcycle battery as the power source.  This means the starter button passes less than 0.2 A to operate the starter via the relay and solenoid.
The 30A rating of the contacts is required to handle the electrical load imposed by the solenoid coil, i2 in the marked single line diagram.  
The solenoid contacts are substantial and are designed handle the motor current on high starting torque.  Motor current is proportional to the torque delivered.
We have three separate circuits with three different current levels:
i1 - is the push button and starter relay at 0.2A
i2 - is the starter solenoid circuit and will typically be 10 to 20A
i3 - is the starter motor current and will be in the 100A+ range.

Terminal 30/51 tends to gradually overheat causing further oxidation.  The current is then limited by the resistance of the contact in series with the relay contacts and solenoid coil.







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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken-Guzzibear Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jul 2016 at 07:19
I use the relays from "Pyro Dan" they are smaller and work ...easy to fit to a base they are there to replace the oem relays in the V11 series bikes he has full specs on his page , irrespective the mod works well and never had a start relay fail with it , the oem wiring however causes this relay to die regularly .. ok one can always flash the starter but that is not fun
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jul 2016 at 13:37
OK first of all this has nothing to do with the current passed through the start button. It is about the feed to the relay contact which when energised puts current to the solenoid.
There are two coils in the solenoid, a heavy duty pull in one and light holding one. The heavy one takes about 25 Amps, but normally it's only in use for a fraction of a second as it is shorted out when the main contact is made.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Motoguzzler Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jul 2016 at 18:11
Okay, my mistake I had thought you were referring to the starter button but you did say ignition switch. ....

Edited by Motoguzzler - 28 Jul 2016 at 18:18
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jul 2016 at 18:25
The mod avoids all the connectors and ignition switch contacts, and fusebox, through which the higher current path for the solenoid has to pass, by providing a shorter more direct route with far fewer connections. Just a small resistance in any one of these contacts, or the summary of two or more, can prevent the solenoid operating because of a Voltage drop across the resistance.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Griffic Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jul 2016 at 23:09
I did the wiring mod on my 1200 sport about 4 years ago after suffering this problem. However, it still occasionally will blow the 15 amp fuse supplying the starter relay. It appears random and often goes perhaps 50 or 100 starts with no issues and then might blow 2 or 3 fuses in a row. I've cleaned the relay contacts and battery terminals and also tried a new relay but with no success. I'm tempted to stick a 20 amp fuse in, but can't help feeling this is not the right way to fix it. What would people suggest?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Motoguzzler Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jul 2016 at 01:44
I would go back to cleaning of contacts with an ultrasonic cleaner.  The Molex connectors Guzzi were fond of are not really suitable for exposed conditions - used them in 1990's electronic designs so aware of their limitations.  The Japanese sorted this with O ring sealed connectors.  The 1/4" spade connectors on the starter relay have a 25A rating when new...not when oxidised and aging.  Localised heating also affects the connection resistance and the I squared R performance begins to become critical at the point of contact.  DC performance of fuses is quite interesting with pre-arc and trip-arc timing governed by capacitive and resistance of the circuit e.g an RC circuit with a time constant.  It is actually quite interesting at 1000V and 200A!!!!
My observation is that the Guzzi engineers had this right for a new installation but did not account for degradation for the various connectors, connections and contacts in a less than ideal climate.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jul 2016 at 08:26
I occasionally get the problem too. I did find the solenoid itself was sticking a bit. I took it off and cleaned all the sticky dried grease off the plunger. Smeared a little light oil on it and refitted. That did help.
the other known cause is low battery volts.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 30 Jul 2016 at 01:26
Originally posted by Brian UK Brian UK wrote:

I did find the solenoid itself was sticking a bit.


I think this is it.

I did measure the DC resistance of the closing winding of my Bosch starter solenoid, it was a virtual dead short. The winding wire is quite thick. However when the solenoid is pulled back it's supposed to be switched out, leaving just the holding winding. It's only inductive reactance of the thick winding that prevents it blowing the fuse, if however the solenoid is too slow to move it may allow the reactance to drop to zero, then the remaining low DC resistance will blow the fuse. Same result if it's not closing the contact at full travel.



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 30 Jul 2016 at 08:24
I see it more as the fuse takes time to heat up and melt.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 30 Jul 2016 at 15:00
There is that too. And repeated heating of a fuse weakens it resulting in eventual early failure.




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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken-Guzzibear Quote  Post ReplyReply Direct Link To This Post Posted: 30 Jul 2016 at 18:54
in reality once the mod is done it fails then how often ...NEVER ON MY 265,000 MILE v1000 .... come on here ....  back to real World guys replaced starter ONCE  had it refurbished earlier this year THAT is like 40 yrs 265,000 miles started about 2x a DAY on average .... in reality with pop to fuel etc more .....
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