Startus Interuptus Revisited

[Kiwi_Roy]

I haven't posted anything on this topic for a while, not here anyway.
The other day I thought I would calculate how much current the solenoid on my Griso should draw while it pulls the gear into mesh, I'm pretty sure the same starter is used on any of the CARC bikes.
I say should draw, based on Ohms law, Current = Voltage / Resistance.
The first thing to do is measure the solenoid coil resistance, so taking my trusty Fluke I touch one lead on the spade connector and the other on the main ground to the chassis, you might like to follow suit.
It soon becomes apparent that it's difficult to get a good reading.
For a start the meter leads themselves are a significant part of the reading.
Shorting the two meter leads together you will get a reading that can be subtracted from the total resistance across the coil.
Measuring across the coil I got a reading of 0.4 flashing 0.5 Ohms
The reason for the inaccuracy is you are right at the end of your meters useful resistance range and it's very hard to get a good contact to the chassis.

So what can you do to get a better reading?
Electricians use a method commonly known as a drop test, this doesn't include dropping it on the concrete.
What they do is pass a known current through the unknown resistance then measure the Voltage drop and by Ohms law calculate the unknown resistance.
Whereas the Ohm-meter only uses a few milliamps of current now we can pass a significant current and get a decent Voltage reading.
I used my bench power supply set at 2 Amps, if you don't have a power supply you can use a battery charger or even the bikes battery as the power source along with a fairly large bulb for example a 20 Watt stop light. The stop light should give you 20 / 12 = 1.66 Amps you can check this with your Ammeter in series.
Now pass that current through the solenoid coil. The magnitude is not critical, you just need to know what it is, using a lamp gives you a fairly stable current, without a lamp it would likely be too much and overheat something.
You will need to remove your Ammeter unless you have two meters but connecting the current source back you will see the bulb is glowing same brightness as before (same current)

Now is the interesting part, switching the meter to DC Volts (don't forget to change the leads to the right socket) you can now measure the Voltage drop caused by your test source. Touch one lead on the coils spade connector the other on the chassis somewhere. Make sure you don't connect the meter at the same point you are injecting the current or your reading will be skewed by the connection resistance.

Now you have the current through the coils and also the Voltage across them you can calculate the resistance very accurately.

[Kiwi_Roy]

Going one step further you can now calculate how much current the coils should draw.

So what's the point of all this?
It's to let you see how the factory wiring leaves much to be desired.

Why did the factory get it so wrong?
For one thing they didn't draw the solenoid how it really is, they missed out the most important coil, the one that does most of the work.

The solenoid on my Griso measured 0.2515 Ohms
At 12 Volts that calculates as 12/.2515 or 47.7 Amps

In reality it drew only about 23, half what it should because half the Voltage went missing in action.

[Kiwi_Roy]

Bump (bump start haha)

Here's what I'm trying to convey in comic form.


From the schematic you can see that the resistance is made up of two circuits, the Holding Coil and the Pull In Coil in series with the motor Armature, actually nearly 80% of the current flows in this latter circuit but only for a split second.

[guzzisteve]

Does that mean bump start?

[Kiwi_Roy]

Many a true word spoken in jest

I could see I was getting lots of views but no comments

"there goes Roy rabbiting on again" LOL
As far as I know the V7 haven't started failing yet but it's just a matter of time.

[Lannis]

Many a true word spoken in jest

I could see I was getting lots of views but no comments

"there goes Roy rabbiting on again" LOL

Nope, I've watched you at work and am always interested in your analyses.

But I've been out installing a new throttle cable on my BSA A10 that doesn't want to be installed, nothing's simple as you know.   And it keeps me from jumping on posts ....

Lannis

[guzzisteve]

It was an opportune time to say bump start, fit in to the topic too. Most valuable info for someone that want's to learn. Just letting you know we are listening Roy 

[Kiwi_Roy]

It was an opportune time to say bump start, fit in to the topic too. Most valuable info for someone that want's to learn. Just letting you know we are listening Roy

Yes, I became pretty good at that with my old brit bikes, VII Sport and Calli II, getting too old for that nonsense now.

At anything less than about 23 Amps the solenoid will sit there all day, all it will do is blow a fuse now and then.
At 30 Amps it will pull in so fast it will make your head spin.
At 47 Amps, who knows, it will work as designed.

[guzzisteve]

I think the new Chinese starters on V7's are doing a good job for them.

[Kiwi_Roy]

I think the new Chinese starters on V7's are doing a good job for them.

Do they not have a solenoid on those., the Bosch, Valeo and Lucas all have the high current solenoid
It's not the starters fault, it's the way they are wired.
I must have a look next time I see a V7
I wonder what the resistance/inrush current is on those, perhaps somebody will measure it as an exercise.
I notice they have a separate key switch and ignition switch
I also see on Carls diagram of the 2013 series it looks like it has lots of un-fused wiring
The Griso starter looks smaller than many of the previous ones but the solenoid draws just as much current, I will pull mine apart and see how it's built.
If only the factory would show the solenoid correctly I'm sure Startus Interuptus would be put to bed.

[Thunderbutt]

I certainly appreciate you taking the time to explain this. Your previous posts helped when I was sorting my Norge electrical gremlins.  And because of that we were able to trouble shoot and repair the other Norge while we were on our trip to Canada last year.

PS- I think you have a real future as a graphic artist for Sunday comics

[Wayne Orwig]

Now pass that current through the solenoid coil. The magnitude is not critical, you just need to know what it is, using a lamp gives you a fairly stable current, without a lamp it would likely be too much and overheat something.

Be careful using a lamp as a current limiter. The resistance varies a good bit with temperature.
If a 12 volt lamp passes 1 amp at 12 volts (12 ohms), it will likely be over 0.5 amps at 6 volts (less then 12 ohms). Always try to measure the current to be sure.

[SED]

Great info.  Really appreciate the wiring diagram - much clearer for me!

I take it the fix is the same as for the small blocks - route battery voltage direct to the starter relay rather than through the  ignition switch?

Thanks!

[Kiwi_Roy]

Be careful using a lamp as a current limiter. The resistance varies a good bit with temperature.
If a 12 volt lamp passes 1 amp at 12 volts (12 ohms), it will likely be over 0.5 amps at 6 volts (less then 12 ohms). Always try to measure the current to be sure.

Wayne, the coil resistance is very low, ~0.25 Ohm the same with the Ammeter at a guess 0.2 Ohms so meter in/meter out the Voltage is almost identical.
We are only using it to calculate the resistance, in my case with 2 Amps the Voltage was only 500 mV
I believe the lamp is much more stable than using a low Voltage like a 1.5 Volt cell which would give about 6 Amps but fall off quite quickly.
However I agree, if you have two meters by all means use one for current the other for Voltage.
Its many times more accurate than using a multimeter to measure Ohms directly.

[Kiwi_Roy]

Great info.  Really appreciate the wiring diagram - much clearer for me!

I take it the fix is the same as for the small blocks - route battery voltage direct to the starter relay rather than through the  ignition switch?

Thanks!

I assume by Small Blocks you mean the Breva, yes (this is similar to the MPH fix as well) I haven't seen any problems with this approach, the start logic stays the same.
I haven't had the opportunity to study the V7s yet but I suspect they are effected also
BTW the early VIIs and the early CARC bikes came that way from the factory. Except on the latter the wire was so tiny it limited the current. (on mine anyway)
You need to be more inventive with the EV and Jackal etc because they use a 5 pin relay.

[not-fishing]

Concrete I understand, electrics not so much so they just leave me confused.

After getting stuck in Toole, Utah with a case reoccurring case of "interruptus", I purchased a Li-poly jump pack (More Power!!) then put a relay on the starter solenoid once I made it back to California.

Thanks for the pointer at the Utah, Roy

Mark

[Kiwi_Roy]

Mark,
        I think your Griso is like mine, it doesn't go through the ignition but is fed from fuse C which is alive.
You can verify that by unplugging the relay and seeing if socket 3 of relay (3) is alive with the key off.

The wire from pin 3 to the solenoid spade connector is too small, replace it with #16 and it should be good, that's all I did to mine

Of course your relay is ok as well.

http://www.thisoldtractor.com/guzzi007/schematics/2006_Griso_1100.gif

I see from your next post I picked the wrong bike, yes your 03 LeMans is wired through the ignition, half an Ohm there would be all it takes to stop it cranking.
Interestingly enough my first Guzzi was an 01 Green VII Sport, its older sister. This bike wasn't wired through the ignition but direct by the factory
The switch measured 18 Ohms but it still cranked like a champ. You would think the factory might have learnt something from that.
http://www.thisoldtractor.com/guzzi007/schematics/1999_V11_sport.gif  Trace the wiring from the start relay, back from the relay, through a fuse direct from the battery.
It had other wiring issues but starting was not one of those.

[not-fishing]

Actually I put the relay on the 03-Lemans.  It was the bike giving me all the trouble and had a little wire to the solenoid.

Of course I checked my Lemans engine ground and found it at 200 ohms.  After a little sanding of the trans, cleaning the lugs the new reading was 0 ohms on my $40 meter.  I really don't like the transmission bolt that the lug is attached to but I kept it in the same place.

Cleaning all the connections and adding the relay is a Belt and Suspenders thing.....

Mark

[guzzisteve]

Never had a problem w/EV and start. The rest are 60's, start w/key and big wires. I have 2 from 80's and no problems.

If riders of this new junk were smart they would carry a jump wire to run 12V from Batt to the spade on solenoid, just a touch and you're going. No bull or fuss.  This is what I used to do, I wouldn't even discuss it, I'd just start it.

[Wayne Orwig]

Never had a problem w/EV and start. The rest are 60's, start w/key and big wires. I have 2 from 80's and no problems.

If riders of this new junk were smart they would carry a jump wire to run 12V from Batt to the spade on solenoid, just a touch and you're going. No bull or fuss.  This is what I used to do, I wouldn't even discuss it, I'd just start it.

Even easier, a screwdriver, wire or such from the 12V on the solenoid to the spade lug on the solenoid.

I was surprised at the number of people that don't know how to bump start a bike.

 

[guzzisteve]

For some reason Roy riders had a box w/lite bulb and a coil of wire. 

[Jurgen]

Do they not have a solenoid on those., the Bosch, Valeo and Lucas all have the high current solenoid
It's not the starters fault, it's the way they are wired.
I must have a look next time I see a V7
I wonder what the resistance/inrush current is on those, perhaps somebody will measure it as an exercise.
I notice they have a separate key switch and ignition switch
I also see on Carls diagram of the 2013 series it looks like it has lots of un-fused wiring
The Griso starter looks smaller than many of the previous ones but the solenoid draws just as much current, I will pull mine apart and see how it's built.
If only the factory would show the solenoid correctly I'm sure Startus Interuptus would be put to bed.

A good article to explain starter/solenoid wiring in addition to Kiwi Roy's cartoons is Bob Nuckolls article in the Aeroelectric Connection.  http://www.aeroelectric.com/articles/strtctr.pdf   
Jurgen

[Kiwi_Roy]

A good article to explain starter/solenoid wiring in addition to Kiwi Roy's cartoons is Bob Nuckolls article in the Aeroelectric Connection.  http://www.aeroelectric.com/articles/strtctr.pdf   
Jurgen

This is a very good description of how the solenoid works but ignore the first diagram, that's how Guzzi show it wrong
Figure 3,4 & 5 are closer to our bikes except we have a relay in place of the button and our wiring goes through the ignition switch
Figure 6 is how we should be wired with just the relay circuit wired through the switch.
NB the author calls the relays contactors, don't be confused by that.
On looking again at figure 6 the full starter current 150 Amps or more is passing through 2 sets of contacts in series, that's not good.
The author explains that in the last paragraph.

I think our combination of starter with solenoid and relay is perfectly adequate if it's wired right.

[Kiwi_Roy]

I had the solenoid from a Bosch starter on my bench so out of curiosity I pulled it apart. I thought some of you might be interested. I unwound the two coils.
The heavy 16 gauge is wound on first, this keeps the wire much shorter for less resistance
The 250 turns will have a potential magnetic strength of 40 Amps x 250 Turns or 10,000 Amp Turns
This is the coil Guzzi ignores on their schematics, the strong one.
The lighter 20 gauge wire (the one Guzzi shows) is wound over the top. As the wire is longer as well as smaller it only draws ~ 10 Amps and the magnetic field it produces is much less 10 Amps x 300 Turns or 3,000 Amp Turns

From these numbers you can see the heavier coil is 3 times as strong, Whatever Voltage gets through to the solenoid will be shared on a 3:1 basis, if only 6 Volts gets through (this is typical) the coils will only be half strength.


Shows the plunger

Removed the wire, the heavy gauge is on first with the light gauge wound on top

[Diploman]

Picking up on GuzziSteve's comment about the apparently excellent functionality of Chinese starters fitted to the current V7 series, I have to say that I am quite impressed by the "Valeo Clone" Chinese starter ($75, Ebay), I fitted to my V50II.  I rewired the starter to the "Hayes fix" configuration, and installed a new starter relay to replace the medieval-looking Magnetti Marelli OEM starter relay.  The new Chinese starter has been impeccable from the outset: not only does it crank significantly faster than the OE Bosch, but it never hesitates or seems to be needing more voltage.  And to boot, the Valeo clone is meaningfully lighter weight than the Bosch.  I'm not surprised that Guzzi has gone to Chinese starters for the V7: the venerable, heavyweight, direct-drive Bosch starter has indeed been overtaken by the more modern, lighter and more powerful planetary-drive Valeo type.  Progress.

[bad Chad]

I didn't read everything preceding, so.   

I ride a 07 B1100.  It doesnt have the startus treatment, just stock on that front.  It always turns over, it's 11 years old, why am I so lucky?

[Kiwi Dave]

I didn't read everything preceding, so.   

I ride a 07 B1100.  It doesnt have the startus treatment, just stock on that front.  It always turns over, it's 11 years old, why am I so lucky?

Just wait.  It will appear at the most inconvenient moment.  You might not be so lucky then.   

Cut the yellow wire on the starter relay, feed the battery positive via an in line fuse to the relay.  Isolate or use as a switched supply the other part of the yellow wire.  What could be simpler?  Peace of mind insurance for very little outlay in time or money.

[Kiwi_Roy]

Actually being an 07 Chads bike might be wired differently like my 07 Griso
It doesn't go through the ignition switch.
But on mine the wire from the relay to the solenoid looked like the metric equivalent of 22 AWG
I upped the size to 18 AWG and the solenoid now engages 3 x as fast, I don't think it will ever suffer.

Now I can't find it, if it has a yellow wire going to the start relay it's as Dave says
http://www.thisoldtractor.com/guzzi007/schematics/2007_Norge.gif

Here's my early Griso, if you look closely you will see the start relay (3) terminal 3 is fed from Fuse C which is always alive, it was the little bitty wire from relay (3) terminal 5 to the starter solenoid I replaced, The time it took to engage dropped from 50 milliseconds to 15 milliseconds.
http://www.thisoldtractor.com/guzzi007/schematics/2006_Griso_1100.gif

Chad, it would be interesting to see how yours is wired, is the start relay terminal 3 alive with the key off or not, since it's not a Norge it might be a little different like my Griso.

BTW Dave, I would also look at the wire from start relay 5 to the starter solenoid to see what size it is, Luigi might have skimped there too, think 40 Amps, I'd be interested to see what you find

 

[Kiwi Dave]

On the Breva 1100, the start relay is fed from the ignition switch (the yellow wire).

[Kiwi_Roy]

On the Breva 1100, the start relay is fed from the ignition switch (the yellow wire).

Yes, i understand that, you just told Bad Chad to change his so it's not that way.
All the later CARC bikes are wired in similar fashion they will fail too.
I have a theory that Luigi thinks the solenoid draws 10 Amps, that's why he can't figure it out.
If he drew the solenoid correctly he may figure it out.