Startus interruptus fix caused other problems. Advice needed please!

[Tomchri]

Jim, your on the way to figure this out. Kiwi Roy and gstallons have a picture here somewhere of the wiring of an extra start relay. I used a 70amp relay ( overkill ),picture of that here to.

 Cheers Tom.

[Tomchri]

19 hours ago, Jim in NZ said:

Tomchri, thanks for your reply. Yes there's so much information on the forum, but it is very confusing as to what advice applies to what model - I've already made a wrong judgment on that! I'm in unfamiliar territory here.

If I understand you correctly, I have to put the wiring back how it was (somehow). Then I can use the power that currently goes from relay terminal 87 down to the spade terminal of the starter motor, to operate the solenoid of a new relay. The heavy current side of the new relay would connect the battery + terminal to the spade terminal on the starter motor. Have I got that right?

Could you please explain what you mean by "just take care of your kill switch,,, and the other electric connections" ?

I appreciate your help, thank-you.

Cheers,   -Jim.

I used a 20amp fused wire to the new relay  directly from +.  The kill switch is your only weak point in the starting process with an extra relay,,, meaning keep it clean from oxidation,, Deoxit Gold makes sense. And that goes for all electric connections on the bike.

 Cheers Tom.

[Jim in NZ]

OK, cheers, thanks Tom. I have been lucky so far with no electrical troubles. I've had the bike since new for 98,000km (61,000miles), so can't complain! It lives in a dry garage, and I haven't ridden it in the rain very much, so I'm sure that has helped its reliability. I still love the bike (and this forum).

[Kiwi_Roy]

Hi Jim,

Unfortunately if you run a direct feed to the start relay of this bike it results in the lights coming On with the key off as you describe because 87A is alive with the key Off. Most other Guzzi models use a 4 pin start relay or leave the 5th pin un-used. 

There are a couple of ways around this

1) Restoring the original 30 feed from the ignition switch and adding an extra relay triggered by the existing trigger wire to the solenoid, this seems to be the way you are leaning at the moment. I would put that relay down by the starter and feed it's 30 contact with a 20 Amp fuse from the large solenoid hot terminal. The nice thing about this method is you don't really need to alter the original loom, the wimpy feed and tiny wires are perfectly adequate to supply the new relay coil.

2) Supply a direct feed to 30 (as you did) but clip the wire off the Start relay 87A contact and re-direct it to the wire you clipped off the Start relay 30 so now the ignition switch turns on the headlight relay directly (but now the headlight doesn't switch off while cranking). To get around this cut the ground off the Headlight relay coil and extend it down to the large terminal of the starter solenoid, not the live one but the one that goes to the starter motor. Now while the motor is cranking both coil terminals of the headlight relay are at 12 Volts so the relay drops out, when not cranking the relay coil is grounded through the starter motor.

I'm not sure why you cannot get the ignition switch apart, First of all you only remove the two Phillips screws underneath the steering head to let just the contact block drop off leaving the lock in place. Tilt out the white contact plate by releasing the odd clip of the switch barrel. Drop off the battery Negative to make it safe or unplug it at the headstock. Putting it back, fasten the switch wires to the rear cover so the wires don't bend and snap where they are soldered to the switch plate.

 

BTW A dirty ignition switch is often the prime reason for "Startus Interuptus", the Starter solenoid can draw up to 50 Amps for the split second while the gear is engaging, there are two coils in the solenoid not just the one the factory show, the Guzzi wiring and weak ignition switch chokes the solenoid through wimpy wiring to less than 30 Amps so it performs badly. With a direct feed the starter will engage 2-3 x faster.

[Jim in NZ]

Hi Kiwi Roy,

Thank-you for your reply. After a false start, I had the problem that you say. I then decided that your post dated Sept 8, 2019 was the one to go with (same as your option 2 above) as it was simpler and didn't require another relay. (We were under a high level of Covid lockdown at the time.) I had to cut open the wiring loom to retrieve enough of the wire that I had cut off start relay 30 - everything is placed very tightly with absolutely no slack! Anyway, I just successfully finished it yesterday.

I haven't yet got to the issue of the headlight staying on during cranking. I think that will have to wait until I next have the rear shock reservoir and starter cover off. But now that I have your instructions I will know what to do.

I removed the electrical half of the ignition switch as you say. As far as I can see, the only place you can take it apart any further is at the joint 1 cm up from the bottom, which requires pressing in a couple of tiny black tabs. I was not able to move these at all. It looks like, if I could do that, I could then remove the white plate that you mention by pressing in a couple of white tabs further up the barrel. You can't remove the white plate from the top of the barrel - the top and the sides are all one moulding. Are there variations in the switch, or am I missing something?

In any case I am at least mobile again now, thanks to your and others' help on the forum. I have been putting this off for literally years, until it reached the stage that it wouldn't start at all, so I am very grateful for all your electrical know-how on this forum. My nearest Guzzi dealer is over 300 km away, and I wouldn't be at all confident handing it over to them anyway!

Cheers.   -Jim.

 

 

[gstallons]

I installed my "starter relay" into the starter solenoid signal wire .  The solenoid wire to terminal 86 . Ground wire to terminal 85 . B + from the starter solenoid battery terminal (battery cable) to 30 and then attach  the start solenoid wire to the remaining wire on the starter solenoid and to terminal 87 .    

This takes ALL the current  required to operate the solenoid and run it through the relay . Yes , this is a good cure and a good preventive measure .  

P.S. this has cured a lot of "no-start" conditions .  If you want to test this to see if it is the problem , try to start your bike , if it does nothing , pull the wire off the solenoid and use a test light to see if the light comes on when you try the start button . If it lights up , get busy .

[billgreenman1]

I want to do this, but my brain fades and it all becomes "qvatch". I'm sure I'll figure it out eventually. 

[Chuck]

Well, Bill.. it's much better to figure it out in the shed than sitting at a gas pump at night in the rain with a no start condition.. It's pretty simple.

[guzziart]

Yeah, after reading posts in this thread and in another one or two, I'm going to add a 6th relay.  In a former post here somewhere I saw a diagram by Stewgnu where a 6th "High Current" relay was added, that will be the way I proceed with this to prevent a potential future problem.  I think it is along the same lines as what Gstallions described above.

On my 03 Lemans, I've got, what seems to me, a 16 ga. brn/blk to the starter solenoid....not very heavy gauge wire for carrying any kind of substantial current.  So, I'm kind of wondering how much current is actually flowing through there once the solenoid hold-in coil takes over after the pull-in coil has been initiated.  I have a couple things going on with Lemans right now but once I get it somewhat more together where I can re-connect the batt, etc., I plan on jumping battery+ to the solenoid spade terminal with an ammeter in between to see what the draw is.  I imagine the draw might be high for the first few milliseconds but after that I would expect to see 8 amps or less.  Just curious I guess....and maybe too much time on my hands.

[Kiwi_Roy]

I just came back from 6 weeks holiday, (central Nth island), unfortunately the computer I had wouldn't access this site.

If you are still having a problem we should be able to sort it out fairly quickly.

You should have been able to get the switch apart, as far as I know they are all the same, the root cause is probably dried out lube inside

 

[guzziart]

Hi,

FWIW, I installed a "high current" starter relay as described here previously.  I got a relay & harness assembly from Greg Bender (This Old Tractor) that was basically "plug and play".  His assembly comes with a relay base that piggy backs on to the existing relay bank, a 30/87 harness runs down to the starter solenoid (one lead plugs into starter, the other plugs into existing 87 from OE start relay) and a fused batt Pos lead to HC relay term 30.  It works great and mimics what gstallons described earlier.

On another note, I checked solenoid draw.  With the engine cold, jumping from bat Pos to the solenoid terminal on the starter my intial draw was 7amps and as the starter engaged and began cranking the draw dropped to 4amps.  On my 2nd attempt the intial draw was 4amps and remained at 4 amps.  I didn't try a 3rd time.  

Oh...this was on my '03 Lemans.

PS - I also posted this at "(solved) Had to get a jump start from roadside assistance...."

[Kiwi_Roy]

On 5/2/2022 at 2:29 PM, guzziart said:

Hi,

FWIW, I installed a "high current" starter relay as described here previously.  I got a relay & harness assembly from Greg Bender (This Old Tractor) that was basically "plug and play".  His assembly comes with a relay base that piggy backs on to the existing relay bank, a 30/87 harness runs down to the starter solenoid (one lead plugs into starter, the other plugs into existing 87 from OE start relay) and a fused batt Pos lead to HC relay term 30.  It works great and mimics what gstallons described earlier.

On another note, I checked solenoid draw.  With the engine cold, jumping from bat Pos to the solenoid terminal on the starter my intial draw was 7amps and as the starter engaged and began cranking the draw dropped to 4amps.  On my 2nd attempt the intial draw was 4amps and remained at 4 amps.  I didn't try a 3rd time.  

Oh...this was on my '03 Lemans.

PS - I also posted this at "(solved) Had to get a jump start from roadside assistance...."

It's not easy to measure the solenoid current you'll just have to trust me.

I discovered that the solenoid has two coils one day when I was playing around with the 2001 VII Sport I had at the time. I put my meter on Ohms and measured the resistance from the solenoid spade to chassis, I was surprised to find less than 1 Ohm. That particular model VII has a direct feed to the start solenoid from the battery so it never suffered from Startus Interuptus, it would always crank.

I did some further testing and found that the two coils measure 1.25 Ohms and 0.25 Ohms and will draw up to 60 Amps for a split second (you can calculate the current by simple Ohms Law 12 Volts / 1.25 Ohms = 9.6 Amps 12 Volts / 0.25 Ohms = 48 Amps for a total of 57.6 Amps (substitute a slightly higher Voltage and it 's well over 60) All Guzzis with electric starters have this double coil but if you look at any Guzzi schematic you will only see one, ask yourself could that be the reason the factory has never cured Startus Interuptus?

If you look closely at the spade connector on the solenoid you should be able to see the two coil ends soldered to the terminal. I have pulled a solenoid apart and found each coil has around 300 turns of wire the reason there is such a difference in resistance, the lower resistance 0.25 Ohm uses a heavier gauge wire and it's wound on first so the wire is much shorter whereas the 1.25 Ohm coil is lighter gauge and the wire is much longer as its wound over the top.

This heavy current only occurs if there is no resistance in series and it drops to just the 1.25 Ohm coil (~10 Amps) as soon as the solenoid contact closes 10 - 20 milliseconds after the start relay closes. On most bikes you will barely get 30 Amps through the ignition switch and spaghetti wiring so of course the solenoid is only pulling at half strength and waiting to fail.

My apologies to Tesla, I will revert to something I learnt as an apprentice back in the 1970s The magnetic strength of an electrical coil is the product of the number of wire turns and the current flow expressed in Ampere-turns a unit not used very often these days . The 1.25 Ohm coil which I call the holding coil (because that's what it does) has 300 turns x 9.6 Amps = 2,880 Ampere Turns, that sounds like a lot until you calculate the other coil 300 x 48 = 14,400 Ampere Turns, so it's obviously doing the Lions share of the work, I call it the grunt coil because it does all its work in a split second, funny that the factory don't acknowledge this coil in their schematics.

I'm sure some of you have had trouble with the 15 Amp fuse blowing, this happens as the resistance builds up so now the Grunt coil can't quite get the solenoid to move, it sits there drawing about 25 Amps for several seconds until the fuse pops. Why do the factory supply a 15 Amp fuse? my theory is they measure the solenoid current with a meter ~ 10 Amps, so a 15 would be appropriate, they completely miss the heavy current drawn by the Grunt coil because it happens so fast 15 - 30 milliseconds, too fast for the meter to catch. You can actually measure this peak current by disconnecting the main feed to the solenoid contact, then the high current will be there as long as the relay is closed.

You probably think its just a simple circuit, the solenoid just pulls the starter in while the button is pressed but there's something interesting going on when you take your finger off the button, you no longer have power on the solenoid spade but the coils are still powered up via the closed main contact, now the coils are connected in series, current feeds back through the Grunt coil from the motor terminal to the spade terminal and so to the Holding coil to chassis. The thing is because its going backward through the Grunt coil and forward through the Holding coil  and they both have 300 turns the fields cancel each other out so the solenoid lets go.

[gstallons]

Is this some kind of jacked up pull / hold winding like some solenoids use ? 

[Pressureangle]

1 hour ago, gstallons said:

Is this some kind of jacked up pull / hold winding like some solenoids use ? 

'Peak/Hold' is how it's referred to in Fuel Injectors. 

[Kiwi_Roy]

13 hours ago, gstallons said:

Is this some kind of jacked up pull / hold winding like some solenoids use ? 

I guess so, it's quite common in DC coils, other times they have a single coil then add resistance once the magnetic circuit is closed.

AC coils don't need that because when the magnetic circuit is open the coil draws a lot more current, once the magnetic circuit is complete the reactance (AC resistance) goes up and the current drops.

The factory don't seem to be aware of that, they only show one coil and don't allow for the heavy inrush current. As a consequence the wires and fuse is too small.