Lets talk magnetos.

G/day from OZ.
Not had a lot to do with magnetos, ran one on a 69 commando I had years ago with the the mag mounted on the rear case where the original chain driven timing set up resided.
Looking at a timing cover mounted mag for my rebuild. Don't like electronic ignitions as I have had them fail in the past.
There are a few suppliers, JS included, but I got access to a unit came off a Shovelhead Harley (mag only) and wondering if the correct base and mounting arrangement were used, would it work. Are they the same? (mag only)
I seem to recall, correct me if I'm wrong, but Triumph units rotate in the opposite direction so they wont work. I have access to lathe and mill so no problem with the extra bits needed.
Thanks in Advance.
JUG

The direction of rotation of a rotating armature magneto is affected by the 'K - angle', which is the angle between where maximum magnetism occurs and where the points open. To change the direction of rotation is an internal wiring problem, however it can probably be solved by a competent person. Rotating magnet magnetos are usually more reliable than rotating armature types. Not only because the capacitor is usually external and can more easily be replaced. On racing Triumphs, a Lucas SR2 magneto is usually better than a Lucas Wader. I suggest that fitting either type to a Commando engine, is not a simple problem.

Direction of rotation is not a wiring issue: it's a cam and points position issue.
A magneto can work in either direction, if you arrange for the points to open at the right time in relation to the armature poles passing the magnets (or magnets passing the pole shoes on a rotating magnet type of magneto).

I think you are right, the position of the capacitor in a rotating armature magneto is probably not relevant to the direction of rotation. I only know that I went to several race meetings when I had rotating armature magnetos, only to have them fail as soon as the motor got hot. I found a Lucas SR4 and ran two leads to each plug and had no further problems. I use a Boyer on my 850, however I would much rather use a magneto.

Late model magnet type.

With the correct base, will this work. Picture for reference only.

Joe Hunt magnetos are available in both rotations. I am fairly certain they have a Norton Commando unit available. Not cheap, but worth EVERY PENNY.

grandpaul said:

Joe Hunt magnetos are available in both rotations. I am fairly certain they have a Norton Commando unit available. Not cheap, but worth EVERY PENNY.

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Worth ever penny to Joe Hunt. I was replacing coils on mine every two or three race weekends.

Agree with Triton, cam and points change when direction of rotation changes, in order to keep proper "K angle" as acotrel notes. Otherwise, the physics of the magneto does not care which way it rotates. The manufacturer of your mag probably can provide a cam-points assembly should you have to change direction of rotation.

The direction of rotation is usually specified when looking at the driven end of the magneto shaft.

Does your magneto have an internal timing advance mechanism?

Slick

The Joe Hunt maggies are the best for the Norton I had a older one on my Triumph for over 9 years it was only a 2 rare earth magnet but the newer ones are 4 rare earth magnets which inturns more spark, the one I had on my Triumph in 9 year on my bike it started first kick every time, done 250,000 ks with it on the bike as it was my only transport at the time and the only maintenance I did on it was oil the cam felt, clean the points with Metho do not file the points as it takes the harding off the points and they will wear out quick, I still had the same points in it for the 9 years and had to lube the outer bearing as it wasn't a sealed bearing, other than that I had no problems at all with it.
I now have a newer Joe Hunt maggie on my hot Norton it has the 4 rare earth magnets and man does it kick arse, it has been on my Norton for over 7 years now with no problems at all and is also a first kick everytime, the first kick for the day you have to give it a big kick but after its been started for the day it will fire up on half a swing on the kicker and I can do that sitting on the seat.
They cost a bit to buy but once set up it will last a life time of trouble free use, a lot of people will jump in and say they have no advance on them, they don't need to you set them up full advance at 28d as normal timing but the plugs have to be set at 18tho not 25tho as standard and it will fire first kick every time, a lot of people don't like them sitting out side the timing cover but I love it out there, they run cooler and in my opinion they look the part and the best thing is when people ask what it is you can make up so many BS stories.
I have all my stock timing marks set up in side ot the maggie housing, when I need to do any maitenance on the maggie I set the timing at 28d pull the maggie off and work on the bench when finish I put it back in the same position and the timing is still set.
I get any parts I need sent over from JH and only takes about a week to Aussie land, I have only sent for a tune up kit for it which includes new points, capister and spark leads which I still haven't used, if you don't file the points they will last a life time and once set up properly it will never need to be touched, all I mostly do is take the front cover of every so often and a few drops of STP on the points felt to lube the points cam.
I am a big believer of JH maggies and if you search on here about maggies you will get a lot of imfo from me and others who use them, but you will also get a lot of people who have never used one before and say things they don't know what they are talking about, if you need advice about the JH maggie I am only to happy to help.

Ashley

texasSlick said:

Agree with Triton, cam and points change when direction of rotation changes, in order to keep proper "K angle" as acotrel notes. Otherwise, the physics of the magneto does not care which way it rotates. The manufacturer of your mag probably can provide a cam-points assembly should you have to change direction of rotation.

The direction of rotation is usually specified when looking at the driven end of the magneto shaft.

Does your magneto have an internal timing advance mechanism?

Slick

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Not sure, its an old one been laying around for a few years but looks like the one I had on my 69.

Guess I'm looking for the simple answer. Change the base and I'm good to go? Yes No? Pretty sure the rotation on the mag is the same.

A Harley isn’t a 360 degree twin, so surely it won’t work?

ggryder said:

Worth ever penny to Joe Hunt. I was replacing coils on mine every two or three race weekends.

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I would guess something wasn't quite proper on your particular unit. Did you have Hunt inspect it?

grandpaul said:

I would guess something wasn't quite proper on your particular unit. Did you have Hunt inspect it?

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The primary windings would fail open circuit. I was going to send a bunch of them back to Joe Hunt. Can't remember if I did or not (it was 4 or 5 years ago), but either way they did not show much concern for my heavy coil consumption. I wasn't impressed by the product or the customer service. May be they're ok on road bikes, but not up to frequent and sustained 7k rpm vibration and the heat associated with that? Mine was mounted on the timing chest behind the cylinders, where I'll admit it did look great.

If you install a late model magneto with "rare earth" magnets behind the engine on a Norton it will fail as the heat will cause the magnets to loose their magnetism. Been there done that.

Curie temp of an NdFeB magnet is around 300F degrees. Over time they slowly loose their magnetism at lower temps. Jim

The best thing you can do is contact Joe Hunt direct as they will tell you if it will fit or needs to be remaginized to run the other way as I am not sure by just changing the points direction will make it run the other way, when I brought my first JH I got it from a mate who ran it on his racing Triumph I brought it for my Norton off him but because the Triumphs run the other way I set the points up to run the Norton way but it didn't work and was told it need to be remaginize to run the other way and cost at that time was $100 to do, so I just mounted it on my 81 Triumph Thunderbird, at the time JH didn't make one for the Norton set up, but if you send JH a email they will answer any questions you may have, they are good to deal with.
I have never put a timing light on mine as I don't have one but once static timed it will fire up and If you get a bit of kick back I just retard it ever so slightly till no kick back and starts on first kick, it will run at from low revs to full revs and beyond and the quicker it spins the bigger the spark, but best thing of all is no need for a battery, a lot less wiring needed, but if you do a lot of night riding then run with a very small sealed battery as running with a battery elimator and off your alt you will have a dull head light but it still works and will get you home in the dark.

Ashley

comnoz said:

If you install a late model magneto with "rare earth" magnets behind the engine on a Norton it will fail as the heat will cause the magnets to loose their magnetism. Been there done that.

Curie temp of an NdFeB magnet is around 300F degrees. Over time they slowly loose their magnetism at lower temps. Jim

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The other Jim runs his JH behind his motor on his hot Atlas and don't seem to have any problems but I run mine off the timing side and is out in the open getting the same cool air the motor gets, my JH on my Norton has done about 50,000 miles on it now with no problems at all.
My Norton use to be a everyday ride but in 2013 when I brought my new Triumph Thruxton its semi retired like me but when I do take it out it always starts first kick even if it has sat for a few weeks at a time.

Ashley

ggryder said:

The primary windings would fail open circuit. I was going to send a bunch of them back to Joe Hunt. Can't remember if I did or not (it was 4 or 5 years ago), but either way they did not show much concern for my heavy coil consumption. I wasn't impressed by the product or the customer service. May be they're ok on road bikes, but not up to frequent and sustained 7k rpm vibration and the heat associated with that? Mine was mounted on the timing chest behind the cylinders, where I'll admit it did look great.

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Well they sell maggies for Dragsters and race engines as well for hi performace ski boats and may other hi powered motorcycles and they have been around for a long time, I have never had any problems with their customer service and I have been dealing with them for over 20 years, I have only replaced one coil and that was when I went down on the maggie side I damaged the front cover and broke a spring that comes out of the coil, it still works but replaced it incase so is in my spare parts collection, I just glued the spring back in.

Ashley

Joe Hunt magnetos were used pretty much exclusively on the late fifties and early sixties Indy roadsters. Lots of good stories about car owners complaining, and Joe himself defending his product.

ashman said:

The other Jim runs his JH behind his motor on his hot Atlas and don't seem to have any problems but I run mine off the timing side and is out in the open getting the same cool air the motor gets, my JH on my Norton has done about 50,000 miles on it now with no problems at all.
My Norton use to be a everyday ride but in 2013 when I brought my new Triumph Thruxton its semi retired like me but when I do take it out it always starts first kick even if it has sat for a few weeks at a time.

Ashley

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Out in the air there is no problem. Short rides behind the motor they will last quite a while.

One good long road ride with it behind the motor will do it in. Like a couple day trip across the country... Jim