Coils,which one is which

Hi guy , i plan to fit paxon ignition on my 750 1970 commando s this weekend, the manual refers to coil one ,coil 2, i havent pulled it apart yet so have no idea if they are marked, which is which sitting on bike

Cheers

Rob

I presume you are fitting the Pazon "Sure-Fire" system (as the Smart-Fire system includes a special dual output coil)?

Both coils should be identical? And, as you will be rewiring them to work in series with the Pazon kit, the coil numbering is not really that important, as both coils produce a spark together each time, so whichever coil you connect the red Pazon box wire (+) to, can be considered to be the No.1* coil, and the other No.2.
What is really more important is that you connect the wiring to each coil (+ & -) terminals as shown in the Pazon diagram.


As your Commando is a 1970 model I expect it still has Lucas 12V coils? (check the numbers on the base of the coils)
Wiring two 12V coils in series may give a weaker spark than two 6V coils, as was used on later Commandos from 1971-on which also incorporated a ballast resistor. The Pazon instructions (note 7) says to disconnect the wiring from the ballast resistor, however as yours is a pre-'71 Commando then it shouldn't actually have one!

The Pazon instructions also mention that 6V coils (or a 12V dual output coil) are recommended, so it may be worth changing the coils to get better sparks if they are 12V?


*Coils are generally numbered according to which cylinder they serve, however for some, that is understood as being numbered from left to right as you sit on the bike, but for British bikes it can actually be the opposite way, the cylinders being numbered right to left as Triumph/BSA Triples are!
A quick look through the Norton service manuals, and the cylinders only appear to be referred to as either 'left' or 'right'.

so you would suggest putting 6 volt coils on. a 12 v system its hard to get the head around but i will go with the advice, do i just go buy a stock 6v coil ?rob

Rockyrob said:

6 volt coils on. a 12 v system its hard to get the head around

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Basically, with electronic ignition systems (Boyer, RITA, Pazon, Sparx etc.. but not Tri-Spark Edit: That information refers to the pre-Classic Twin sequential Tri-Spark ignition that's no longer available) the coils are changed from 'parallel' to 'series' wired. Two 6V coils wired in series with a 12V supply share the Voltage, each coil getting 6V. Two 12V coils connected in series will also only get 6V each, so are running under power, and is the reason that twin 6V or single 12V dual output coils are recommended.

The original points system used parallel wired coils, 12V being supplied to each coil separately, as the ignition circuits of each cylinder worked independently of the other.

The 1971-on models still used parallel wired coils, however 6V coils were fitted, and a ballast resistor was connected to the ignition power supply to reduce the battery Voltage.

Pazon recommend either IC06 6V PVL or the original Lucas 17M6 coils or IC05 12V dual coil with a 4.2 Ohm primary resistance for use when the engine's compression ratio is 9:1 or more. Avoid coils that have a low primary resistance as they are not suitable, see the Pazon instructions for that information.

Speaking of which is which - how can you tell the difference between a 6-volt and a 12-volt coil?

Jason Curtiss said:

Speaking of which is which - how can you tell the difference between a 6-volt and a 12-volt coil?

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If it is a Lucas, or PVL check the stamped markings on the base of the coil.

The original Lucas coils would have been either 17M6 if it is 6V or 17M12 for 12V, I think they would originally have had a sticker on the side giving the same info as well? http://www.britishspares.com/118.php

PVL types and others may have 6V or 12V stamped on their base depending on the type, and normally have a sticker on them.

http://www.britcycle.com/Products/391-4 ... 45276A.htm

Thanks L.A.B. - my coils have the 17M6 marking on them and I was wondering if the 6 designated 12 volts.