Atlas charging system upgrade options

Karl Johnson · Jul 19, 2023

So I've acquired a new project - a 1966 Atlas that has been off the road since the early 70s but under cover and out of the way so doesn't look like it's been messed with. As far as I can tell it looks complete.

The bike is fitted with a magneto and from what I have read the reliability of these is not the best. This leads me to my question - what options are there for upgrading the ignition circuit? Is it a simple matter of removing the magneto and installing a Pazon, Podtronics, and stator as are commonly fitted to later models such as the Commando? Im keen to hear from others what they have done.

Triton Thrasher · Jul 19, 2023

The magneto has nothing to do with the charging system.

Karl Johnson · Jul 19, 2023

Triton Thrasher said:
The magneto has nothing to do with the charging system.

My bad - sorry I meant ignition system

Mike40M · Jul 19, 2023

Atlas came with either magneto or battery ignition. If your magneto is working, keep it. You have to get a magneto replacement body to fit an electronic ignition. See http://www.norbsa02.freeuk.com/goffypazon.htm
Early Commandos, late Atlas and 650SSS came with a contact breaker housing at the same place as the magneto. Later Commandos moved the contact breaker to the end of the camshaft.
With a battery ignition you need to have an perfectly working electrical system, not to be left stranded if something fails. As long as a magneto works, you'll get home.
Have some bikes with magneto ignition. For me they have been reliable. As long as they work, I'll keep them. Drawback can be problem with the auto advance. Too many things can go wrong with a battery ignition.
Also have some points ignition bikes and one with a Boyer Mk IV.

baz · Jul 19, 2023

There's a lot of pros and cons with either Magneto /points/electronic
Personally I prefer a Mag
But points or electronic are good depending on the charging system as stated above
If opting for the mag I'd suggest having it rebuilt by a reputable expert
It's probably an original mag and over half a century old
I've no doubt it'll work when you clean the points and pickups
But it may not be for long with the age of the shellac and condenser
What do you plan to use the bike for? Local rides of further afield etc?

Karl Johnson · Jul 19, 2023

Mike40M said:
Atlas came with either magneto or battery ignition. If your magneto is working, keep it. You have to get a magneto replacement body to fit an electronic ignition. See http://www.norbsa02.freeuk.com/goffypazon.htm
Early Commandos, late Atlas and 650SSS came with a contact breaker housing at the same place as the magneto. Later Commandos moved the contact breaker to the end of the camshaft.
With a battery ignition you need to have an perfectly working electrical system, not to be left stranded if something fails. As long as a magneto works, you'll get home.
Have some bikes with magneto ignition. For me they have been reliable. As long as they work, I'll keep them. Drawback can be problem with the auto advance. Too many things can go wrong with a battery ignition.
Also have some points ignition bikes and one with a Boyer Mk IV.

Thanks for the advice, Mike. I now how two magnetos, which could be handy. The Atlas project also came with a "spare" motor, gearbox, primary drive, twin Mikunis and a magneto as part of the lot. The spare motor has the "15" number prefix so either a 1956-58 Model 77 or Nomad. May spoon that into another 66 Triton build and turn that one into a sort of Domiracer hybrid. I am familiar with needing a perfectly functioning battery ignition system - I've experimented with a 3-phase charging circuit on my 72 Commando and have first hand experience this works until it smokes (if not using a open circuit reg/rec). This is my first foray into the world of magnetos though so full of questions that I haven't been able to find clear answers to.

For the moment I'll run with the magneto and see how it goes and that I'm happy with the reliability. As long as there is one good magneto out these two that'll work. I can always send off the other one to get refurbished.

Thanks - karl

Karl Johnson · Jul 19, 2023

baz said:
There's a lot of pros and cons with either Magneto /points/electronic
Personally I prefer a Mag
But points or electronic are good depending on the charging system as stated above
If opting for the mag I'd suggest having it rebuilt by a reputable expert
It's probably an original mag and over half a century old
I've no doubt it'll work when you clean the points and pickups
But it may not be for long with the age of the shellac and condenser
What do you plan to use the bike for? Local rides of further afield etc?

I think I'm going to stick with the magneto for the moment. After I replace one of the exhaust valve guides that had split and button it back up, I should be in a position to try starting it up and see how it goes.
My plan for this bike is to turn it into a one-kick daily runner, use it, and maintain it well. I also have a 66 Triton and 72 Combat Commando I ride a few times a week regularly. Both are able to be taken further afield...

Thanks - Karl

Schwany · Jul 19, 2023

What I did:

I moved the ignition out into the timing side cover like it is on Commandos and currently run a Commando cam, TriSpark ignition, a small wallet sized Antigravity lithium iron battery, and TriSpark reg/rect. Not particularly simple to do. Simple to maintain though.

I still have all the pieces to put a K2F in a old Norton, but won't ever do it. Way too fiddly to setup the AAU and get at the points. I like simple.

Karl Johnson · Jul 19, 2023

Schwany said:
What I did:

I moved the ignition out into the timing side cover like it is on Commandos and currently run a Commando cam, TriSpark ignition, a small wallet sized Antigravity lithium iron battery, and TriSpark reg/rect. Not particularly simple to do. Simple to maintain though.

I still have all the pieces to put a K2F in a old Norton, but won't ever do it. Way too fiddly to setup the AAU and get at the points. I like simple.

Ohhh...now you have me thinking a bit. Some nice mods. Did the Commando drop right in or did it need some modification? Along with those mods did you swap out the original stator to something later like an RM21 or 24?

Schwany · Jul 19, 2023

Karl Johnson said:
Ohhh...now you have me thinking a bit. Some nice mods. Did the Commando drop right in or did it need some modification? Along with those mods did you swap out the original stator to something later like an RM21 or 24?

The cam and ignition didn't drop right into my P11 motor. The P11 cases were modified to use a SS cam and initially points ignition in a Commando timing cover. I put electronic ignition and a battery in it later. Some other things were done to help get air out of the crankcase because the SS cam I used then did not have any timed breather porting in it. Might have done some other things for the oiling, but I think the P11 motor was more like a Commando motor as far as oiling the top end and return oil was concerned. Anyway, lots of cam solutions are available today to build a nice looking restored sleeper hot rod. Don't have to do what I did or had done to be more precise.

The P11 did not have an alternator in it when I got it. It was a basket case amateur flat track bike that only used the magneto for ignition. Stripped down no lights and so on. I installed a Lucas two wire single phase stator and Lucas rotor in it. To be honest I have no idea what the output is on the stator. My bike is still very simple and doesn't need much from the alternator. Minimal wiring for an LED head light, tail light and ignition as well as wiring up a battery to the key switch for the ignition and lights. the 2 wire alternator keeps the battery from going dead and the lights bright.

At the time there were a lot of people around that knew how to do the modifications to the Atlas cases to use a Commando cam and Commando ignition. The modifications are not extensive, but there is no going back if I am not mistaken. I had the work on the cases done by someone Bob Raber of Raber's Parts Mart knew. I was kind of busy chasing ladies and partying at the time.

Today you can get a hot cam for an Atlas engine and keep the magneto and whatever alternator and electrical setup you have if desired.

The other members here are a better source for what can be done with your bike. I just mentioned what I did for grins. Besides I don't have a lot of brain left to pick any information out of. I'm a over confident parts changer with a bad memory.

gpzkat · Jul 19, 2023

I have an N15CS with the K2F magneto, but it was completely rusted and an iffy rebuild candidate. The cost of mag rebuild was $600 to start. Sold it for parts (cleaned up) on eBay for $90 and put that toward a housing and Wassell mini micro MK2 with housing for $375, then a single 12v coil and a small battery. I had to re-use my auto-advance, I safety wired it to disable movement. If yours is behind the cylinders like mine, which I think it must be, then changing to the later position off the camshaft end isn't so simple I think, seems a case change would be needed.

I also put in a 3-phase alternator and a Podtronics voltage regulator. I don't know if it's the best or the right setup, but it's what I decided on after research. I haven't fired it up yet but am very close. Hope it works! Here's a pic of the housing and rotor mounted, I just got finished aligning it to 30 BTDC give or take a degree, hence the supplied tool still is attached. I am happy not to have to fuss with adjusting points, and I read about rebuilt mags going one year which sorta scared me off. But others love them, so who knows? If my mag wasn't junked out I'd have run it.

texasSlick · Jul 19, 2023

First off, I am biased towards magnetos. I disagree with those who say they are too fiddley. Once set up, they run and run, ..... no more reliable ignitions available.

I do admit refurbishing a K2F is costly, one has to consider applying the cost to refurbish a K2F to the purchase of a Joe Hunt, currently $795 US for the flange mount JH. That is practically a wash. Replacing a Lucas K2F with a Joe Hunt is a simple bolt up procedure.

Keep your K2F's as long as they are functional. The archilles heel of the Lucas K2F is the internal capacitor, as it ages it shorts out when hot and will kill the engine. If refurbished, new capacitors are of the polystyrene type that have an indefinite life. Changing out the capacitor is not a DIY project, and will most likely result in an off center rotor at least and internal damage at worst, when attempted by a novice.

Refer to Resources Page 7 for a tutorial on setting up and timing a K2F.

Slick

texasSlick · Jul 19, 2023

Regarding charge system upgrade.

I changed all my lamps to LED's, installed a Podtronics regulator / rectifier, and replaced my stator with an older 3 wire type. Then , I modified my wiring so that on PILOT lighting selection, the low output of the stator is used to charge the system. On MAIN lighting selection, the high output of the 3 wire pair powers the system. With an LED head lamp, I do not need the full stator output. This scheme avoids having the Podtronics dump excessive power to earth.

Slick

Karl Johnson · Jul 20, 2023

Schwany said:
The cam and ignition didn't drop right into my P11 motor. The P11 cases were modified to use a SS cam and initially points ignition in a Commando timing cover. I put electronic ignition and a battery in it later. Some other things were done to help get air out of the crankcase because the SS cam I used then did not have any timed breather porting in it. Might have done some other things for the oiling, but I think the P11 motor was more like a Commando motor as far as oiling the top end and return oil was concerned. Anyway, lots of cam solutions are available today to build a nice looking restored sleeper hot rod. Don't have to do what I did or had done to be more precise.

The P11 did not have an alternator in it when I got it. It was a basket case amateur flat track bike that only used the magneto for ignition. Stripped down no lights and so on. I installed a Lucas two wire single phase stator and Lucas rotor in it. To be honest I have no idea what the output is on the stator. My bike is still very simple and doesn't need much from the alternator. Minimal wiring for an LED head light, tail light and ignition as well as wiring up a battery to the key switch for the ignition and lights. the 2 wire alternator keeps the battery from going dead and the lights bright.

At the time there were a lot of people around that knew how to do the modifications to the Atlas cases to use a Commando cam and Commando ignition. The modifications are not extensive, but there is no going back if I am not mistaken. I had the work on the cases done by someone Bob Raber of Raber's Parts Mart knew. I was kind of busy chasing ladies and partying at the time.

Today you can get a hot cam for an Atlas engine and keep the magneto and whatever alternator and electrical setup you have if desired.

The other members here are a better source for what can be done with your bike. I just mentioned what I did for grins. Besides I don't have a lot of brain left to pick any information out of. I'm a over confident parts changer with a bad memory.

Thanks for shared what you did to your Atlas. It certainly gives me some ideas to run with!. Thanks - karl

Karl Johnson · Jul 20, 2023

texasSlick said:
Regarding charge system upgrade.

I changed all my lamps to LED's, installed a Podtronics regulator / rectifier, and replaced my stator with an older 3 wire type. Then , I modified my wiring so that on PILOT lighting selection, the low output of the stator is used to charge the system. On MAIN lighting selection, the high output of the 3 wire pair powers the system. With an LED head lamp, I do not need the full stator output. This scheme avoids having the Podtronics dump excessive power to earth.

Slick

Thanks for that. I'm quite familiar with the Podtronics setup and not afraid to try going that route (battery ignition). I'm goin to see how much the the magneto setup "inspires" me first. Thanks - karl

Karl Johnson · Jul 20, 2023

gpzkat said:
I have an N15CS with the K2F magneto, but it was completely rusted and an iffy rebuild candidate. The cost of mag rebuild was $600 to start. Sold it for parts (cleaned up) on eBay for $90 and put that toward a housing and Wassell mini micro MK2 with housing for $375, then a single 12v coil and a small battery. I had to re-use my auto-advance, I safety wired it to disable movement. If yours is behind the cylinders like mine, which I think it must be, then changing to the later position off the camshaft end isn't so simple I think, seems a case change would be needed.

I also put in a 3-phase alternator and a Podtronics voltage regulator. I don't know if it's the best or the right setup, but it's what I decided on after research. I haven't fired it up yet but am very close. Hope it works! Here's a pic of the housing and rotor mounted, I just got finished aligning it to 30 BTDC give or take a degree, hence the supplied tool still is attached. I am happy not to have to fuss with adjusting points, and I read about rebuilt mags going one year which sorta scared me off. But others love them, so who knows? If my mag wasn't junked out I'd have run it.

Thanks for the pic. That mod certainly seems pretty straightforward to install. If the magneto doesn't work, this may be my preferred option. Thanks - karl

Schwany · Jul 20, 2023

Karl Johnson said:
Thanks for shared what you did to your Atlas. It certainly gives me some ideas to run with!. Thanks - karl

P11 actually, but the motor is similar. The Wassel EI magneto replacement like what gpzkat did is where I would go with your Atlas. What I did was a case splitting exercise and machine work. Not worth doing today.

gpzkat · Jul 20, 2023

A couple of things I liked about that little housing in the mag location is that I can keep my tach drive off the right front (cam end) and also hide the single coil with a simple bracket as shown. Not sure that would work on an Atlas but I saw an N15CS on BringaTrailer that mounted it under the tank and it is nice and tidy.

There may be 'better' ignition housings, perhaps more weatherproof but I think it will be fine for my usage. I also looked into one that fits inside the Lucas magneto housing. There are a couple of types of those including a complete Lucas setup ($650 with the ignition included), and they keep the cool original look. I just went for the least expensive way.

Schwany · Jul 20, 2023

gpzkat said:
A couple of things I liked about that little housing in the mag location is that I can keep my tach drive off the right front (cam end) and also hide the single coil with a simple bracket as shown. Not sure that would work on an Atlas but I saw an N15CS on BringaTrailer that mounted it under the tank and it is nice and tidy.

I have a very similar coil, although it is mounted behind the carburetor filters. Too much big cable stuff going on in that space on my P11 to put it where you did. It produces a good enough spark to light up a Norton 750 twin in one kick. The Chinese dual coil has not given me any grief at all in 2500 miles. I don't ride as much as I wrench. lol

mdt-son · Jul 22, 2023

gpzkat said:
ISold it for parts (cleaned up) on eBay for $90 and put that toward a housing and Wassell mini micro MK2 with housing for $375, then a single 12v coil and a small battery. I had to re-use my auto-advance, I safety wired it to disable movement. If yours is behind the cylinders like mine, which I think it must be, then changing to the later position off the camshaft end isn't so simple I think, seems a case change would be needed.

If using the AMC-type points housing (first introduced on the G12 in 1964, from 1967 on the P11, G15, Atlas and 650SS followed), there is no need for the external auto-advance. The AMC-type ponts housing allows a plain sprocket to be fitted at the cylindrical shaft. There was an internal AAU in the points housing, similar to the fitment of all other british twins at the time. The internal AAU and the associated points plate is replaced by the EI rotor and pickup plate.

If you can't find a used AMC-type points housing, all necessary parts (points housing, shaft and sprocket) are available from Andover Norton.

From what I've seen, Wassell's housing is not weather-proof, which may affect the EI pickup plate in the long run. The AMC-type points housing offers a weather-proof solution.

Although a magneto is a very fine and reliable instrument for competition use, switching to EI brings many advantages for a road bike, for instance, no points wearing out, no sliprings failing, idle stabilization, provision of a rev limiter, etc. Fitting an EI is a natural consequence of upgrading the electrical system, which most restorers opt to do.

- Knut

Atlas charging system upgrade options

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