Breva 750 oil light... Only in neutral?

[sign216]

 The wire from relay to solenoid can be another weak point, minimum 18 AWG 16 even better.

K-Roy,

Is thin wire feeding the solenoid a known weakness of the 750 engine, or is this just a general statement?

Joe

[drdwb]

Update



I will note that the left bolt holding the dash in place seems to have sheared off or the plastic has broken. It wobbles around easily, but is still held in place. Maybe that contributed to it somehow?

On my wife�s 750 the PO had dropped it a couple times broke turn signal and windsheild mount on right side,dash very wobbly, the both rubber mounting bolts had bolts out of rubber, I tried to fix with silicon, left hand side the fix worked, right hand needed repair 2 more times, I thought I was just making it to tight, bought new one from dealer. Installed but didn�t over tighten, still pulled out, even though I inspected mounting very carefully, couldn�t see any problem, I did silicon fix again, but reinstalled with 2 washers as spacers, 2000 miles since still ok. So something was misaligned.

Wife loves the bike, So do I, It�s a blast to ride, so lite,nimble and quick, great bike for one up touring for her, and when she lets me, I enjoy thrashing it on the back roads, sometimes it�s more fun than my Norge. But there are little things that a little more quality or perhaps thought or expense in production and finish would make a better product. Too bad it had such a limited run.

Thanks for the post, I am always thankful for the info I get from this forum that help keep our Guzzi�s going.

[Muzz]

 Too bad it had such a limited run.

It was close to 5 years out here.

[Kiwi_Roy]

K-Roy,

Is thin wire feeding the solenoid a known weakness of the 750 engine, or is this just a general statement?

Joe

More of a general statement,
I wasn't actually having a problem with my Griso yet, I just thought I would check it out for Startus Interrupts potential, I fully expected to find the start relay wired through the ignition switch like most other modern Guzzi but no, for this year they wired it direct (similar to the MPH kit) but I was shocked to find a tiny wire from the relay to solenoid, the equivalent of 20 gauge, if they can do it on this model who knows what is done on others.
I calculated that for a decent current it would drop 15% of the Voltage. Later Grisos have a wire more like 18 gauge, still on the light side IMHO

Before I started I topped up the battery with a few hours on the tender.
Using my Oscilloscope I measured the current flowing to the solenoid, from the trace you can see how long it took from the time the start relay closed to when it started cranking. The current shot up from zero to 22 Amps, wavered around a bit as the solenoid moved in the magnetic field and dropped to 10 Amps as soon as the main contacts closed. You cannot measure this current with a regular digital meter, you may get some indication with an old analog one.

With the OEM 20 gauge wire it took ~50 milliseconds (red trace)



I didn't take too much notice of the wire I replaced it with with, at the most 16 AWG but you can see how for a few cents the change in speed was significant. (green trace)

I haven't measured the coils on this starter solenoid but other Valeos I measured are capable of drawing 48-50 Amps at 12 Volts.

After what I found on the Griso I say check the wire size between relay and starter.
If the relay is powered through the ignition switch do yourself a big favour and change that with either an MPH kit or home brewed option.

The time it takes for the solenoid to operate may seem very short but remember this is with a new battery fresh off the tender, it will take much longer if the battery is getting on in years and half flat.

From all the variations in starter wiring over the years it's obvious to me that Luigi is really struggling to solve the Startus interrupts problem. He's not helping himself by not showing how the solenoid coil/s are really wired, the later schematics bear little resemblance to reality.

[sign216]

Kiwi,

Thank you for the test, this is excellent info.  If they used thin 20 ga wire between the relay and the solenoid for the Griso, then you know they did it for the older/smaller bikes. 

How convoluted was the path between solenoid and relay for your Griso?   I have to brace myself before I go into my bike's wiring; it can be an Alice-in-Wonderland experience between the diagram, the unreliable wire colors, etc. 

And...I'm surprised to see you measure wire diameter in gauge.  In NZ aren't they Metric?

Joe

[Kiwi_Roy]

And...I'm surprised to see you measure wire diameter in gauge.  In NZ aren't they Metric?

Joe

Yes they are metric but they were Imperial when I did my apprenticeship wire sizes were 1/044, 3/029. 7/029 etc or British Standard Wire Gauge but I live now in Canada where they still haven't decided what to do so I'm more familiar with American Wire Gauge. Probably the only Metric wire I see is on my Guzzi and electrons aren't picky so it gets replaced with AWG sizes.

[sign216]

Yes they are metric but they were Imperial when I did my apprenticeship wire sizes were 1/044, 3/029. 7/029 etc or British Standard Wire Gauge but I live now in Canada where they still haven't decided what to do so I'm more familiar with American Wire Gauge. Probably the only Metric wire I see is on my Guzzi and electrons aren't picky so it gets replaced with AWG sizes.

Imperial wires sizes, aargh!  It's like you're talking about Whitworth wrenches. 

For most things in the US it's mixed between SAE and Metric, but wire and shotguns are solidly in gauge sizes.