Breva 750 no start

[Jurgen]

Here is a hint for Breva 750 riders if you find that it won't start. 

I was planning a ride to our favorite coffee bar on a beautiful New Mexico morning.  Got the bike out, got dressed, helmet and gloves on, buddy waiting to go, pushed the starter button and nothing.  No clicks, no fuel pump noise, nothing except the dash lights and instruments went thru their initializing.  Banged on the starter solenoid, banged on every relay, nothing.  Checked voltage at the starter solenoid with button pushed.  Dead.  Hmmm.  Couldn't be a fuse since the dash was working?  Turns out the 15A starter safety logic fuse in the secondary fuse box did blow.  No idea why, it was running before I parked it the previous week and has been running and starting well ever since.  Maybe that's why Guzzi gives you 2 extra 15A fuses.

[jackson]

15A starter safety logic fuse in the secondary fuse box

.

I was not aware of a secondary fuse box.  Where is it located?
Thanks,
Jack

[Jurgen]

The secondary fuse box is on the right side of the bike, directly under the top frame rail under the seat.  3" long, 1" wide, hard to get the top cover off, marked FUSES. 

[jackson]

The secondary fuse box is on the right side of the bike, directly under the top frame rail under the seat.  3" long, 1" wide, hard to get the top cover off, marked FUSES. 

Yes, I am aware of that fuse box but to me, that's the main (& only) fuse box on the Breva 750 or V7 Classic,
Is there another one that I'm not aware of?
Thanks

[Railroad Bob]

That's the fuse that's given a lot of us Breva 750 owners a dead bike in the morning.  I think
my old 750 blew that fuse, even in the first few months of ownership.  There are quite a few
threads here in the Board that discuss it.  I think one good way to prevent it from happening
is make sure your Battery is fully charged and topped off at ALL times.  My starter logic fuses
all seemed to blow when the batt was not at 90-100%.  Known issue on the Breva 750s.

[Kiwi_Roy]

Since the starter solenoid can pull 40 - 50 amps, it's not surprising it blows a 15 amp fuse every now and then.
Interesting that it blows when the battery is a bit low, I think the explanation for that is it takes longer to pull the solenoid
in so the high current pulse lasts longer. Out of curiosity I tried on my V11 Sport (same starter I believe), it blew the 15 amp fuse in less than 1/2 second.  
The high current pulse lasts from the time the start relay closes until the solenoid contacts close.

I suggest upping the fuse to a 20, it will still protect the circuit but give you a slightly higher margin.

[Jurgen]

Jackson, You are correct, that is the only FUSE BOX, the so called MAIN fuses (2 x 30A) are under the left side panel, no box with cover, just bare sockets.  In the schematic they are both called fuse boxes, main and secondary.

[Muzz]

It is why I carry 5 spares. ::)

Never needed them yet...........

[sign216]

Didn't Guzzi originally put a 10 amp fuse for the starter relay , and later upgraded it to 15 amp?

[Jurgen]

No, Jackson, those are the only groups of fuses on the Breva 750.  BTW, I'm increasing that particular fuse to 20A to forestall any more blown fuses.  Good electrical design says that you fuse for wire size, and since the wire seems to be about 18 gage, and the 20A or 30A pulse is only about 50 ms long (and the wire is less than a foot long), there is no harm in putting in a 20A fuse to protect the wire. 

Jürgen

[Kiwi_Roy]

and the 20A or 30A pulse is only about 50 ms long (and the wire is less than a foot long), there is no harm in putting in a 20A fuse to protect the wire. 

The short pulse is more like 40 to 45 Amps, it's too fast to read with a digital meter, I agree a 20 Amp fuse is appropriate.