Speedfrog

Not so much for the value of the original relays but only to get some insight into the original design of the electrical system. We all know by now the electrical engineeers in Mandello Del Lario had their share of miscalculations, but I'm hopeful they would have made sure sensitive equipment like the ECU was protected from potentially destructive voltage surges coming from said relays.

@audiomick Here is a good read if you are interested to go beyond basics. https://www.12voltplanet.co.uk/relay-guide.html

I would be interested to know if the original relays were all the same in all positions and if there is any marking on them indicating the presence of a surge suppressor.

Good primer on relays, but no mention of suppressor, diode or resistor, or flyback voltage spikes.

I'm not sure I understand that description. First let's establish that the Voltage Spike happens at the coil side of the relay (low current control circuit), it does not affect the switch side (high current load circuit). When the relay is turned off and the coil is de-energized, the magnetic field collapses, resulting in a voltage surge in the opposite direction. These low current surges can have significantly high voltages, often up to 100 volts, with the potential to destroy a transistor driving a relay. Think of it as a taser, high voltage/low current, it won't kill you but it'll disable you for a while... do it repeatedly or for too long and it'll kill you, same as lightning. A diode(often called a flyback diode) installed in parallel with the coil (pin 85/86) in reverse polarity creates a low resistance loop for that momentary voltage spike to be absorbed/dissipated and protect the controlling electronic circuit while allowing the current to flow directly through the coil when the relay is switched on. So you might think, great, let's use diode protected relays whenever we have a transistor on the control side... well, like everything electronic, it ain't that simple. Although very effective, one drawback to using a flyback diode as a voltage surge suppressor in a relay is that it decays the magnetic field of the coil slower than with no diode, taking longer for the relay to open the contacts and allowing arcing and micro-welds to occur between the contacts which could cause the relay to stick overtime when the contacts become welded together. I believe the built-in diodes found in micro relays are just simple flyback diodes. There are other types of diodes or diode combinations that can be used to alleviate this issue but it's getting a bit more technical that I'm willing to delve into here. Resistors installed across the coil provide similar protection against voltage spikes and are more durable if not as effective. A downside to using a resistor is that it will allow current to flow through it whenever the relay is on and dissipate energy and convert it into heat. The advantage it holds over a diode is that it won't slow down the opening of the contacts and it is not sensitive to polarity. It would be interesting to know what type of relays were spec'd by the Guzzi engineers and whether the ECU has built-in voltage surge protection. The only thing I see on the schematic is a "safety diode" #48 between the ECU relay pin #85 and the ECU, presumably to give it some protection. None of the relays show any suppressor across their coil. Of course, with our bikes being 20+ years old, I doubt there are many original relays left under the seat.

2000 V11 Sport for sale on WG. $4,000 - Southwest PA https://wildguzzi.com/forum/index.php?topic=117324.msg1845191#msg1845191

As long as they are micro relays... the only requisite is that relay #1 (#23 on the schematic) has to be SPDT where all the others are SPST. The physical difference is SPDT has 5 pins and SPST has 4 pins. A SPDT (5 pins) can be fitted in all positions, but a SPST will not function in position #1.

I think it is cheap insurance and that’s what I’ll do. Those Picker relays come in both flavors

That leaves us with the question, would a diode protected relay be beneficiary in position #5 in insuring no voltage spike do any damage to the ECU??

@doccYou are right when you say: But with all due respect, I think you got the energizing of the relays arse about. Let us look at the schematic and those 2 relays in question, we agree that the top one #49, is the ECU relay(#4) and the bottom one #46 is the EFI relay(#5). For reference, Relay pin/terminal identification: 85 Relay Coil Negative - 86 Relay Coil Positive - 87 Common Contact - 30 Feed/ Line In Positive _ The ECU relay #4 gets triggered(pin 86) from the ignition switch via the kill switch. _ The EFI relay #5 gets triggered(pin 86) from the ECU pin #19 Fuse #2 is only protecting the EFI circuit from +12V feed coming from the battery. I don't pretend to be 100% correct but that's what I see.

Looking at the electrical schematic, relay #4 supplies power to the ECU and in turn the ECU triggers(control?) relay #5 to power ignition, injectors & fuel pump. Note that relay #4 is already protected by an external diode. Dang, we need @Kiwi_Roy in-fused science to bring us the light!

@audiomick That’s correct, when the voltage is removed and a relay is the de-energized, the magnetic field sudden collapse can result in a voltage surge in the opposite direction. A diode will offer a better protection to sensitive electronic circuitry upstream of the relay. In that light, I wonder if relay #5 controlled by the ECU wouldn’t benefit from having a diode protected relay to safeguard it from voltage spikes??

Good heavens @docc, you draw faster than your shadow! I had meant to post earlier that I found a cheaper source for the PC 782 relays: https://www.digikey.com/en/products/detail/picker-components/PC782-1C-12S-R-X/12352866 Sorry I couldn’t catch you in time before you pulled the trigger. I’m thinking of changing my screen name to “Slowtoad”... It’s all for a worthy cause though, I’ll be curious to hear what you find out..

Mini and micro relays have different form factors with different pin layout and are not interchangeable. Resistors and diodes have the same basic fonction, resistors are more durable and the preferred choice in automotive applications.

That is my understanding!

Guzzis have a soul, Hondas have a chain... Not to mention better looking!

FWIW, I'll throw this Picker Components data-sheet in the mix. https://www.pickercomponents.com/pdf/Relays/PC782.pdf When I was doing my own research on the best available relays for V11S, I came across this Picker Components as one of the highest rated micro relay readily available, the only one with rated max continuous current in its spec sheet. The PC782-1C-12S-R-X would be the suitable one for our motorbikes: https://www.onlinecomponents.com/en/picker-components/pc7821c12srx-47154342.html

I ordered a set as well for the Café Sport earlier today but I got the regular price ($70)! When I asked Mike about it, he admitted having made a mistake on the price with the earlier order and said he couldn't afford to make that mistake twice - That's ok, I think it's a fair price, especially compared to that of the graphite gaskets. If iirc it had cost ~$100 for Turtle to have a set made almost 20 years ago. Thanks to @dgpmerc for reviving this old thread and bringing this issue back to the forefront. My bike's PO had mention chasing leaks at the headers crossover and replaced the gaskets prior of the sale and told me what a pita it is to remove and re-install the whole exhaust system to replace these gaskets. These shims should solve the leaky/floppy crossover problems and maybe make re-assembly easier and at least more permanent.

Avec la GOMME DUNLOP, the lady with the broom won't catch you till you drop...

Hey Al, with diligent research throughout the 20 years of information contained in this forum, you could write the definitive “Best How-to of V11S maintenance” book for sure! That would be cool!

GUZZIMOTO -— one word! If the Piaggio lawyers knock on your door, tell ’em it’s a Japanese name...

I wonder if the city of Le Mans, France or its namesake race track ever got any royalties from Moto Guzzi...

For more details on these new gaskets and more in-depth information, you can check Rolf’s thread on the Ghetto. https://www.grisoghetto.com/t6888-new-oil-pressure-gaskets-for-the-8v-engine

The general consensus on the oil level with a Roper plate installed is to keep it right below the plate. It’s a good idea to mark your dipstick at that level during install. A small drilled hole works well.

And no reason not to use the thicker paper gaskets as they have been proven reliable, Pete? Your choice, they both improve on the original gasket! The metal core gaskets are actually a bit thinner than the better paper ones - 0.5mm to 0.9mm respectively according to Rolf’s measurements - and since you need two with the roper plate, they will reduce the stack height some but not by any significant amount.