1980 Monza Electrical help

[Acme Monza]

HI all,

My new to me 1980 Monza has a voltage drop off to the headlight and turn signals. Battery is fine as is ground to chassis. With ignition off I read 12v across the battery terminals as well when I test from positive terminal to any point on the chassis. With switch on and testing headlight I get a reading of around 11v. Again with switch on and testing turn signals front and rear I get a reading of around 9v. All tests where done with all lamps disconnected.

Can someone point me in the right direction to test where the drop off is occurring?

Thanks, Andy

Gratuitous pic

[pehayes]

It is going to be at some connection.  Loose.  Corroded.  Weakened Molex socket. Etc.
Start at one end and disconnect/inspect everything.

BTW, there is a discussion forum specific to small_block_guzzi over at Yahoo Groups.  You might get further advice there.

Patrick Hayes
Fremont CA

[Chuck in Indiana]

If you read 12V across the battery terminals, the battery is dead. Nominally, it should be above 12.65.
After you get that sorted out, search for "Monza annual inspection" here. It will walk you through many Monza electrical (and other)things.
Here ya go, Ithink..
https://wildguzzi.com/forum/index.php?topic=89034.0

[Acme Monza]

If you read 12V across the battery terminals, the battery is dead. Nominally, it should be above 12.65.
After you get that sorted out, search for "Monza annual inspection" here. It will walk you through many Monza electrical (and other)things.
Here ya go, Ithink..
https://wildguzzi.com/forum/index.php?topic=89034.0

Yes, I forgot to mention that I am ordering new Odyssey Battery. The link you posted is great! Just what I needed.

Thanks

[Chuck in Indiana]

Glad it helps.  I'm a fan of Odyssey. .

[Kiwi_Roy]

If you look at any of the 1880 Guzzis they all seem to have a 12 way Molex connector half way along the tank.
My Lario was that way, a couple of the molex pins were arcing away, as an intermittent fault, It turned out to be the large red wire going from battery to ignition switch and the brown one going from the switch to the fuses
I tried to replace the pins but the wires were so large and stiff  i ended up just using a couple of crimp links around the outside, you will never need to unplug the connector any way.
Before you crimp the wires dip them in Vaseline, that will ensure they never corrode.

http://www.thisoldtractor.com/guzzi007/schematics/1983_V65_Lario_Series_1.gif

With the ignition On and Headlight On Measure from the chassis (jamb the negative lead under a handy not or clip it to something well grounded)
1/ To Battery +, should be 12+
2/ Battery - should be zero
3/ The red wire at the ignition switch, should be 12+
4/ The common point at the fuses, should be 12+
5/ The load side of the 3 fuses 12+

If you get anything different list it and we can probably tell you where to look next.

As a sparky I have a problem with the way Guzzi run a hot unfused wire from the battery all the way to the ignition switch and back to the fuses, theres 200 Amps or more that could cause a serious melt down if it were to accidentally touch ground.
I like to add a 40 Amp fuse in the red wire, this makes it easy to add headlight relays in the headlight bucket, you don't need to fuse them separately just power the 30 terminals from the main red wire and attach the headlight socket directly to the two 87 contacts.
Take the two original headlight wires and run one to each 85 terminals and the two 86 to chassis.

[John A]

Do your headlight switch a favor and wire in a relay so the switch just runs the relay.

[Acme Monza]

Hi all, this forum is turning out be great! Last year I dealt with electrical on my ‘74 911. So it all seems very familiar. Down to the part about adding relay to the headlight.
It turns out the recommended Odyssey battery is exactly what I am currently running in my car. So I cancelled the order because it happens I have a spare one. Fate!
I’m loving this sweetheart of a little bike. I’ve always liked the Monza. In my youth in the ‘80’s I checked one out at our local bike shop. But, my then wife wasn’t into bikes....marriage lasted 9 month’s.... I’ve owned many Japanese bikes. This is my first Italian. I found her CL only 35 minutes away.

Happy New Year!
And thanks to all.

[Chuck in Indiana]

Can someone point me in the right direction to test where the drop off is occurring?

It's generally a combination of corroded connectors, but the fuse blocks in these old machines are suspect for that. I'd take the shotgun approach, though, and clean and DeOxit all electrical connectors. You'll be glad you did.
Congrats on the Monza.. it's one of my favorite Guzzis.

[Kiwi_Roy]

It's generally a combination of corroded connectors, but the fuse blocks in these old machines are suspect for that. I'd take the shotgun approach, though, and clean and DeOxit all electrical connectors. You'll be glad you did.
Congrats on the Monza.. it's one of my favorite Guzzis.

Are we talking the old pointy fuses, they need some tension on the clips, I usually shine them up by rubbing on some rough cloth, smear a little Vaseline on the ends.
Some guys wrap an "O" ring around the clips to hold them under tension.

[Acme Monza]

Again, thank you all for the needed advise.
I will do a thorough maintenance of the electrical this weekend.
The bike itself is in very good mechanical shape as it's P.O. had a documented top end and carburetors rebuild at around 4000 miles ago. I believe I am the third owner.
Appearance wise the bike has faded plastic and is in need of restoration as a majority of its life was spent in SoCal. And fortunately no major rust or pitting. My intentions are to keep the stock look and add some mechanical and electrical upgrades.

Andy

[Chuck in Indiana]

Again, thank you all for the needed advise.
I will do a thorough maintenance of the electrical this weekend.
The bike itself is in very good mechanical shape as it's P.O. had a documented top end and carburetors rebuild at around 4000 miles ago. I believe I am the third owner.
Appearance wise the bike has faded plastic and is in need of restoration as a majority of its life was spent in SoCal. And fortunately no major rust or pitting. My intentions are to keep the stock look and add some mechanical and electrical upgrades.

Andy