Lost spark on one cylinder

L.A.B. said:

Ignition power should be going to the RITA box, not directly to the coils.

https://i0.wp.com/granttiller.com/w...972-onwards-Commando-Lucas-RITA-AB5.png?ssl=1

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Maybe thats why the 15 Fuse went. I did see spark on the right cylinder after I did it tkhough

Kjell said:

Maybe thats why the 15 Fuse went. I did see spark on the right cylinder after I did it tkhough

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It's valid to test directly to the coil IF you have removed all wires from the coil and if you don't do it long - putting 12volts on a 6 volt coil directly for more than a few seconds can burnout the coil. Trying that test with wires connected at best tells you little of value and at worst burns out your Rita.

marshg246 said:

It's valid to test directly to the coil IF you have removed all wires from the coil and if you don't do it long - putting 12volts on a 6 volt coil directly for more than a few seconds can burnout the coil. Trying that test with wires connected at best tells you little of value and at worst burns out your Rita.

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I connected positive battery to the minus on the first one and then negative battery to the positive on the 2nd one. In other words total 12 volts on the two coils already connected in series. Could I still burn the coils ?

Kjell said:

Could I still burn the coils ?

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Yes, this burnout will happen if they stay connected to a 100% on 12V supply. The points setup and the EI are all switched 12V supplies, they supply power to the coils for only part of each spark cycle ie they are a switched supply. The EI's normally turn off the power to the coils after a few seconds if the engine is not turning to prevent this, on points if one set of points is shut with the engine not running and the ignition on then the coil being fed by those points will burn out.

The test for coils is checking the ohms/resistance.

Lucas 6V coils (17M6) - 1.5 to 2.2 Ohms between the low-tension terminals.

4 KOhms between either l-t terminal and the h-t terminal, infinte Ohms between any terminal and the case.

Kjell said:

I connected positive battery to the minus on the first one and then negative battery to the positive on the 2nd one. In other words total 12 volts on the two coils already connected in series. Could I still burn the coils ?

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If you really did what you say, you were not across two coils and you were backwards assuming that you are still positive ground. If you are negative ground, you always need to say that when asking for electrical help.

You should be wired with ground to one coil's +, that coil's - jumpered to the other coil's +, that coils - to the EI. With the wire removed from the - to the EI and the battery - momentarily connected to that -, when you disconnect it should spark. I'm overly not worried about damaging the coils, I'm worried about you damaging the EI, wiring, and doing test's that just confuse you and us.

kommando said:

Yes, this burnout will happen if they stay connected to a 100% on 12V supply. The points setup and the EI are all switched 12V supplies, they supply power to the coils for only part of each spark cycle ie they are a switched supply. The EI's normally turn off the power to the coils after a few seconds if the engine is not turning to prevent this, on points if one set of points is shut with the engine not running and the ignition on then the coil being fed by those points will burn out.

The test for coils is checking the ohms/resistance.

Lucas 6V coils (17M6) - 1.5 to 2.2 Ohms between the low-tension terminals.

4 KOhms between either l-t terminal and the h-t terminal, infinte Ohms between any terminal and the case.

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Both coils measure 1.7 Ohm.

I am in the process of cleaning up the electric wiring and getting rid of the wiring I dont need as per the schematic that Grant Tiller was kind enough to make me a few years back. In addition I bought a 12V coil/dual output from CNW 3 years back that I will install now along with the latest trispark ignition. That should let me get rid of a lot of wiring to clean up the installation considerably. I have a feeling I smoked the Lucas Rita during my "testing" Judging by the feedback on Rita AB5 its a miracle it lasted as long as it did anyway

marshg246 said:

If you really did what you say, you were not across two coils and you were backwards assuming that you are still positive ground. If you are negative ground, you always need to say that when asking for electrical help.

You should be wired with ground to one coil's +, that coil's - jumpered to the other coil's +, that coils - to the EI. With the wire removed from the - to the EI and the battery - momentarily connected to that -, when you disconnect it should spark. I'm overly not worried about damaging the coils, I'm worried about you damaging the EI, wiring, and doing test's that just confuse you and us.

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Still positive ground I'm afraid which by the way confuses the hell out of me a thinking about the fact that I have a normal battery in the bike .
I still fail to understand why Norton did it like this when the "rest of the world" used negative ground.

Kjell said:

I still fail to understand why Norton did it like this when the "rest of the world" used negative ground.

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Positive ground was quite common at one time not just Nortons and most British bikes of that era were positive earth/ground.
Triumph for instance only went negative ground from the 1979 model year.

L.A.B. said:

Positive ground was quite common at one time not just Nortons and most British bikes of that era were positive earth/ground.

Positive Ground Cars

Positive Ground Electrical System In Old Cars, History and Information

www.restore-an-old-car.com

Triumph for instance only went negative ground from the 1979 model year.

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Having owed nothing but classic cars ( in addition to bikes) I fail to remember one vehicle having positive ground.
Presently own two classic Chevys' both from 1966 ( One 2 door Nova and one 2 door Chevelle) )I have a feeling this was more of a british tradition while the rest of the world went with negative ground. My oldest bike was a 57 Harley Davidson Panhead and yes - negative ground

The present Norton I bought in 2008 and I remember I was quite surprised to find out how the wiring was

Kjell said:

Having owed nothing but classic cars ( in addition to bikes) I fail to remember one vehicle having positive ground.
Presently own two classic Chevys' both from 1966 ( One 2 door Nova and one 2 door Chevelle) )I have a feeling this was more of a british tradition while the rest of the world went with negative ground.

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Nevertheless, positive ground was commonly used on older vehicles not just British.

Also, prior to WW2 (and maybe a short time after?) Nortons were negative earth/ground.
1937 Norton handbook diagram:

...Nortons and most British bikes of that era were positive earth/ground.

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Some of the aftermarket solid state rectifier/regulator units can be wired for either + or - ground, depending which wire from the unit you choose to ground. And if you are just getting a 'new-to-you' old British bike, take note of the charging components and how the battery is wired, as it may not be typical.

Were you able to determine the cause of the one lost spark through testing?

Kjell said:

Having owed nothing but classic cars ( in addition to bikes) I fail to remember one vehicle having positive ground.
Presently own two classic Chevys' both from 1966 ( One 2 door Nova and one 2 door Chevelle) )I have a feeling this was more of a british tradition while the rest of the world went with negative ground. My oldest bike was a 57 Harley Davidson Panhead and yes - negative ground

The present Norton I bought in 2008 and I remember I was quite surprised to find out how the wiring was

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The vast majority of American cars into the 50s were positive ground. In the middle 50s most switched from 6-volt to 12-volt systems and many, but not all, changed to negative ground at that time..

My 54 Mercury was positive ground as was my 56 Ford pickup truck. General motor mostly switched by 1960. I believe that Jaguar took about two years to switch in the middle 60s.

I believe there was some method to positive earth madness, as it was thought to reduce corrosion from road salt.

This forum post on positive/negative ground is very informative

L.A.B. said:

Also, prior to WW2 (and maybe a short time after?) Nortons were negative earth/ground.
1937 Norton handbook diagram:

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The amount of information available and the knowledge of many members on this website don't cease to amaze me.
Here in Norway we have forums for just about anything but most of them is pure garbage.

YukoNorton said:

Some of the aftermarket solid state rectifier/regulator units can be wired for either + or - ground, depending which wire from the unit you choose to ground. And if you are just getting a 'new-to-you' old British bike, take note of the charging components and how the battery is wired, as it may not be typical.

Were you able to determine the cause of the one lost spark through testing?

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I have not done any more testing. Decided to start from scratch since I have to wait for the trispark ignition to arrive
from australia anyway. There are no turnsignals on the bike, zener diode gone etc so I thought I would take the opportunity to clean everything up ( Should have done it in 2008) and start from scratch. Slowly but surely the electricals are coming back to life.
Today I got the horn and the high beam back but discovered the lucas switch were not making contact on the low beam (red/blue wire)and a new switch will run about 100 euros. I think I will leave as it is since its the second switch I have on the bike.
I guess there is a reason why CNW go with other switches on their bikes

KiwiShane said:

This forum post on positive/negative ground is very informative

Model T Ford Forum: Why the Switch to Positive Ground on Modren Fords?

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It is, but some there continue the false statement that current flows from negative to positive. Clearly, if that's true outside a battery, then it's clearly false withing the battery. So, there are two diametrically opposed answers to the question: "Which way does current flow?" or the question: "Which way do electrons flow?"

This mind boggling thing drove me crazy in my first year in college. One day early on, I was in a Electonics class where the professor assured us that current flowed from negative to positive. My next class that day actually had the same professor and it was a Physics class where he assured us that current flowed from positive to negative. At that time, it was mostly a difference in viewpoint as it was still thought that individual elections move through circuits - again, nope!

Next, notice I said current flows, not electrons flow - that is very old thinking. If an atom gave up an electron and that electron then flowed through the wire to the other side - you would be creating new elements or isotopes on both ends - nope! That's why there is "electron hole flow" (hole flow) that is equal and opposite to electron flow. Think of a relay race - that's current.

More info: https://eng.libretexts.org/Bookshelves/Electrical_Engineering/Electronics/DC_Electrical_Circuit_Analysis_-_A_Practical_Approach_(Fiore)/03%3A_Series_Resistive_Circuits/3.02%3A_Conventional_Current_Flow_and_Electron_Flow