6V or 12V coils

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MikeM

MikeM

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Wondering what the advantage or disadvantage is for 6 or 12 volt coils? Just had my automotive coils (previous owner installed) replaced with a proper Norton coil. The tech went with 12 volt which I assume the automotive ones were. Runs good but whats the dif between the 2? Better spark with 12V?
BTW I have a positive earth 12V battery system. Also, I am electrically challenged.
 
L.A.B. said:
http://www.classicbike.biz/Norton/Repair/70up_Commando/70upCommando.pdf
Section J12.
Click to expand...

Thanks for the reply but the link doesnt work.
 
MikeM said:
Seems like either would work. Apparently I dont have the ballast resistors. Its a 71, 750.
Click to expand...

Your '71 model would have had two 6V (17M6) coils and ballast resistor originally, however, as 12V coils have been fitted, the ballast resistor isn't required.
 
L.A.B. said:
MikeM said:
Seems like either would work. Apparently I dont have the ballast resistors. Its a 71, 750.
Click to expand...

Your '71 model would have had two 6V (17M6) coils and ballast resistor originally, however, as 12V coils have been fitted, the ballast resistor isn't required.
Click to expand...



Much better.
 
Are you running points or an aftermarket electronic ignition? Many of the ei manufactures, such as Boyer and Pazon recommend 2 six volt coils wired in series for a better spark.
 
htown16 said:
Are you running points or an aftermarket electronic ignition? Many of the ei manufactures, such as Boyer and Pazon recommend 2 six volt coils wired in series for a better spark.
Click to expand...

OE points at this time.
 
There shouldn't be any difference between 6 v coils with ballast and 12 v coils without ballast for a points system. I'm not sure if the 6V coils were just a holdover from a bygone era, or - as eluded to in the workshop manual - in anticipation of using electric start, where the ballast can be bypassed during starting. That was common practice in the automotive world for many years.

For an EI system though, you can't use (2) 12 v coils in parallel, as it'll likely overload the ignition module.
 
maylar said:
I'm not sure if the 6V coils were just a holdover from a bygone era, or - as eluded to in the workshop manual - in anticipation of using electric start, where the ballast can be bypassed during starting. That was common practice in the automotive world for many years.
Click to expand...


That would appear to be the reason because Commandos had 12V coils and no ballast resistor before 1971.
 
Its to get the sw*ne to start when the battery is half flat .

Once upon a time people rode them everyday , rain hail or shine . Trundling round london in the sleet with your lights on
wasnt gaurenteed to keep the battery charged . If they fitted 6 Volt coils it stopped the riders knocking the Norton Dealers doors in .

If some turkey went skieing , and left it in the snow overnight , it might start in the morning . Believe it or not they were sold
as TRANSPORT mainly . Not as collectors items 40 years down the track .

You could even buy factory hot up parts , if they were to gutless , stock . In that case - the 6 Volt Coils were likely one of the First things to GO .

6V or 12V coils


CYCLE Mag. around 77 when they built this thing ( Whats a Norton ( Current ) lap time ( on Slicks ) compare to this ?? )
They did a COIL TEST . Lucas 6 V came a resounding LAST . The Duke was fitted with $ 10 K Mart Coils - about TWENTY times more Grunt .

But it didnt have to start in the snow on a flat battery . During Warrenty . In fact the paintwork wasnt high on the budget , for most race team .
 
Norton There ./
6V or 12V coils


July 75 . THE GREAT IGNITION COIL SWINDLE .

6V or 12V coils


Next Year they were reasuring British Motorcycle Buyers that the bottom may not have fallen out of their world . Just Yet .
By 1980 & the Darmah Ducati were attempting to produce a ' mass market ' motorcycle , and lauded for their roadholding .
As Triumph & Norton had previously been . But the 4 cyl whazz bang was Here to Stay . As they didnt fit 6V lucas coils . :shock:

Read Ye & weep . Tho the universe I was in I wouldve sworn they listed Lucas 6 & 12 V . The problem with tangental universes :? .

http://www.eurospares.com/graphics/engi ... ilTest.pdf
 
EXCUSE the DIGRESSION , but , while we're there . Brother thought this was marvelous . Ringle ding ding *

6V or 12V coils


Marvelous Swindle . F -750 mutiny . INTERNATIONAL . F I M had Banned them as INELIGABLE for F-750 . Production BASED . Main Engine Castings - Manufactuerers Street Equiped 200 off Homlogation .
but all the silly riders had bought them cause they were FASTEST . Then the A.M.A. had a relapse & let the forign RACE bikes in the A.M.A. F-750 Intl. races . Leaving the F.I.M. ( and ALL the 4 strokes )
to the wolves . Another great racing class perveted .

Anyone seen the D.O.H.C. 12 valve ( 4 per pot ) T150 head pictures . It Did Exist . ANYWAY , rather than having showrooms full of P.r. 5 speed Knortons , they Had This .

6V or 12V coils


which in comparison is the Wholsley Version of the Morris . :( Hindsight Indeed , But ANYTHING , why drop the PII ( Vibes ) why not a Domiracer SS road twin ( they GAVE the COMP. Dept. Away ! Thats Why ! )
or indeed Factory Trained Servicemen FOR the P.R.s and a flagship P.R. in Every Showroom . So Difficult to trasmitt in polite English . In less than 300 Words .

Hop on Ebay & see the Magazines and the cheap tiny Jap Trash that was round . the GS 750 was the first Jap Tripe that mightve steered . Maybe . With 12 yards of suspension travel , and Chassis Member
Dimenisions approaching a Rickman or Seely . Or a Domi ! . :( Commando Motors made by Villiers in the J.A.P. Factory . A misogonous hodge podge . Unfortunately . Under Duress . in more ways than one .

Was only the diehards riding British by 1980 . &0s I met a Young Guy whod Traded his Honda on a 750 Co Op Boonie ( They Dindt have THAT bad a name . EVERYTHING was Anaylised . Most were Dubious in particular respects . " A Car Pulled Out ( in front of him ) and sweved up over the kerb , over the grass , over the corner , and back on the Road ( Young Guy , second Bike ) ' The Honda Wouldnt have done that '
( Saved his neck.) under duress "

So there we are , Sour Grapes . Or industrial Espionage on a grande scale . Or just share market racketeers, blindsightednass apathy and indifferance . A GOLD plated DAIMLER was Superb Marketing Publicity .
( Mk II 250 ) AND It Was HIS Gold ! ( Showed of the lines and workmanship Superbly . Whineing Snots . There ya go .
 
Matt Spencer said:
Its to get the sw*ne to start when the battery is half flat .
Click to expand...

I somehow doubt that was the actual reason (that's what the 2MC is for). If it was, then why wait until 1971 to fit 6V coils?
If there was much to be gained then BSA, Triumph and others would've used the same 'ballast resisted, 6V coils' ignition system on bikes without an electric starter.
 
I don't know it this applies to things Norton.

I have worked on 6 volt and 12 volt autos/tractors. Both systems incorporate ballast resistors. The reason for the resistor was to stop full battery voltage from going to the coil and overheating it*. I believe normal coil voltage on a 12 volt system would be about 9 volts. There is usually a "bypass" mode when the ignition switch is in the start position, this allows full voltage to go to the coil, but even this is not a full 12 volts due the the starter drain. I imagine a 12 coil would ultimately put out a better spark than a 6 volt system, but I bet overall resistance (ohms) also plays into the picture.

Pete

*EDIT: and reduce points pitting
 
Deets55 said:
I imagine a 12 coil would ultimately put out a better spark than a 6 volt system, but I bet overall resistance (ohms) also plays into the picture.
Click to expand...

An ignition coil is a step-up transformer and the difference between primary and secondary voltage is the ratio between the primary and secondary windings, so as I understand it, a 12V coil doesn't necessarily produce a higher output voltage than a 6V coil.
 
maylar said:
SNIP

For an EI system though, you can't use (2) 12 v coils in parallel, as it'll likely overload the ignition module.
Click to expand...

YES you can use 2...12v coils in parallel. The problem unfortunately is they are not identical and therefore the collapsing field are not identical therefore one feeds the other during the collapse and one gets robbed of its power. With a diode in series... with each coil, so there can be NO back feed of either,... they then each act like a normal single coil and make spark. This is a principal also used to fire 3 coils in parallel on a triple.
 
L.A.B. said:
Deets55 said:
I imagine a 12 coil would ultimately put out a better spark than a 6 volt system, but I bet overall resistance (ohms) also plays into the picture.
Click to expand...

An ignition coil is a step-up transformer and the difference between primary and secondary voltage is the ratio between the primary and secondary windings, so as I understand it, a 12V coil doesn't necessarily produce a higher output voltage than a 6V coil.
Click to expand...

Yes I agree. My thinking is start with a higher initial voltage 12v you would need less windings on both sides. Probably cheaper and smaller to build.
I think the move from 6 v to 12 v ( Automobiles) was that the power requirements for the rest of the vehicle increased so much that 12v was a better option.

Pete
 
dynodave said:
maylar said:
For an EI system though, you can't use (2) 12 v coils in parallel, as it'll likely overload the ignition module.
Click to expand...

YES you can use 2...12v coils in parallel.
Click to expand...



But not with certain EI systems (such as Boyer or Pazon) where the current draw from two 12V coils would be likely to overload the box which is what I expect maylar was thinking of?
 
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