Lets talk magnetos.

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All good Jim as I never did like them sitting behind the motor hiding away, maybe why a lot of the old Lucas maggies failed behind all that heat from the motor and a few of them caught on fire from leaking carbies as well, sparks and fuel leaks don't go hand in hand.

Ashley
1973x75 said:
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.
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The new Joe Hunts are a lot better made now and you are talking 60/70 years ago now a long time to hold a gruge or complaint about a product, plus there is Morris maggies that look the same as JH maggies, heat plays a big part on any ingition systems, how many EI system have buggered up from heat or failed for no reasons at all, how many black boxes have failed or batteries gone flat and left stranded, all I know is both my JHs have never let me down and done a lot of long distant trips on both my bikes set up with the JHs over 7 years on my Norton with two slides down the road on the maggise side from not my fault at all, bloody cars pulling out in front of me drivers not paying attention.
All I know is I am giving a honest opinion on my Joe Hunts, if I did have a problem with them I be the first one to complain, but so far have none.

Ashley
 
More often than not, It turned out Joe was right...the car owners and mechanics just needed a conveinient scapegoat when they couldn't figure out their ignition problems. I think I remember reading that being out of the airflow caused too much heat. Not Joes fault.
 
May just keep the mag for my bobber build (shovel) and buy a new modified one from Jim(JS) for the timing cover
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jug.
 
I have not yet seen a Joe Hunt magneto which does not hang out of the right hand side of the motor where it can be damaged.
 
jug said:
May just keep the mag for my bobber build (shovel) and buy a new modified one from Jim(JS) for the timing cover
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jug.
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Then you can't go wrong with everything you need to set up it up, its is easy to set up and tune but what I did is I used soft mounting bolts so if you do go down hard the bolts will break and less damage to the maggie but they are strong and well built as I have gone down twice now without much damage skidded down the road once on the maggie side and fused the plug leads in the front maggie cover, didn't even crack the cover, I still have that cover hanging on my tool board.

Ashley
 
jug said:
Late model magnet type.
Lets talk magnetos.

With the correct base, will this work. Picture for reference only.
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This magneto is similar to the Lucas SR type. The Lucas SR magnetos are able to be changed from one cylinder operation to two or four, by changing what is on the end of the housing and armature. The major advantage is that they are usually cheap. You can often find second-hand ones in machinery junk yards in country areas, on tractors and pumps etc. Fitting one to a Commando would not be easy, and on a road bike the magnets might deteriorate, as Jim says. I never had that problem, but my bike was only ever raced.

The Pal magneto which is used on Jawa speedway motors, might come in two cylinder versions. - Probably European ?
 
acotrel said:
I have not yet seen a Joe Hunt magneto which does not hang out of the right hand side of the motor where it can be damaged.
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Alan most racers won't have them outside because of high speed crashes, you seem to worry about damage from crashing all the time, I never worry about it if it happens it happens, I have seen many on the side of Triumphs bobbers and cafe racers and have seen 2 on other Nortons but a lot of road riders are to tight fisted and won't spend the money on good ignitions systems and if you look closely to my profile pic you will see mine proudly sitting out the side, the idea of riding is to stay upright and if you do go down hard there will be more damage to your bike than the JH they are strongly built, the maggie housing is solidly built out of one peice of alloy billet.

Ashley
 
ggryder said:
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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You'd get arguments on that viewpoint from literally hundreds of people that raced them for many years. I'm not saying I have empirical evidence that the failure rate was low, but as far as I can recall from nearly 15 years on forums and 25 years in clubs, I've not heard of another Hunt failure apart from crashing on them because they stick out in a fall, and they're prone to getting bashed by serious competitors.
 
acotrel said:
This magneto is similar to the Lucas SR type. The Lucas SR magnetos are able to be changed from one cylinder operation to two or four, by changing what is on the end of the housing and armature. The major advantage is that they are usually cheap. You can often find second-hand ones in machinery junk yards in country areas, on tractors and pumps etc. Fitting one to a Commando would not be easy, and on a road bike the magnets might deteriorate, as Jim says. I never had that problem, but my bike was only ever raced.

The Pal magneto which is used on Jawa speedway motors, might come in two cylinder versions. - Probably European ?
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Older magnetos such as the Lucas mag and older Hunt mags used normal [not rare earth] magnets. They are not nearly as powerful and starting takes a little more boot but the magnets survive the temps behind the motor much longer.

Of course any magnet eventually looses it's power and heat will hasten it, but conventional magnets will handle the high temp for years instead of days. Jim
 
ashman said:
Alan most racers won't have them outside because of high speed crashes, you seem to worry about damage from crashing all the time, I never worry about it if it happens it happens, I have seen many on the side of Triumphs bobbers and cafe racers and have seen 2 on other Nortons but a lot of road riders are to tight fisted and won't spend the money on good ignitions systems and if you look closely to my profile pic you will see mine proudly sitting out the side, the idea of riding is to stay upright and if you do go down hard there will be more damage to your bike than the JH they are strongly built, the maggie housing is solidly built out of one peice of alloy billet.

Ashley
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My intention is not to crash. In 38 years of riding I have only put one bike down and that was because some shela pulled out on a stop signed intersection and I had to lay over a brand new 1986 FXR HD to avoid a T-bone accident (VERY EXPENSIVE EXERCISE).
I've never raced but in my younger days I rode like an idiot. Probably more good luck than good management. So as you said "if it happens, it happens"
JUG
 
jug said:
My intention is not to crash. In 38 years of riding I have only put one bike down and that was because some shela pulled out on a stop signed intersection and I had to lay over a brand new 1986 FXR HD to avoid a T-bone accident (VERY EXPENSIVE EXERCISE).
I've never raced but in my younger days I rode like an idiot. Probably more good luck than good management. So as you said "if it happens, it happens"
JUG
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Yep it happens so quick the frist ride on my rebuilt hot Norton and new JH I was only a mile from home and a car in front of me had her left indactor on but when I started to go around her righrt side she turned right, I laid the bike down on the maggie side and stopped before hitting her, when she started to get up me I told her to look at her indactor as the left one was still flashing, thats where it ground the plug lead in a the maggie cover and had to push my bike home, only damage to my Norton maggie cover and broken foot peg, my mate had a spare cover and I had a spare foot peg so was a quick fix.

Ashley
 
joe hunt magnetos quote $865 for a Norton Mag £657 GBP BTH K2F replacement £625 with shipping to the US only a few pounds more ?
 
The thing I wonder about, and have "googled" to try and figure out about magnetos, is why they don't incorporate an advance mechanism into them...

Basically, I thought about sending Jim Comstock this question in a private message, so I could get an actual answer to this question, rather than hear a non-stop sales pitch about how "they don't need one". I'm not knocking them in any way. I just wonder why they wouldn't be a better ignition with a centrifugal advance mechanism... Is the rotating part of the magneto so heavy that an advance mechanism wouldn't work well?? What's the reason that an advance is not incorporated into their design?

Please if you're going to answer, "because it don't need it", that's not an answer to my question. I wondering if there's a reason for it's omission from most magneto designs... I also understand that if you are using one to drag race, you probably don't need an advance curve...
 
o0norton0o said:
The thing I wonder about, and have "googled" to try and figure out about magnetos, is why they don't incorporate an advance mechanism into them...

Basically, I thought about sending Jim Comstock this question in a private message, so I could get an actual answer to this question, rather than hear a non-stop sales pitch about how "they don't need one". I'm not knocking them in any way. I just wonder why they wouldn't be a better ignition with a centrifugal advance mechanism... Is the rotating part of the magneto so heavy that an advance mechanism wouldn't work well?? What's the reason that an advance is not incorporated into their design?

Please if you're going to answer, "because it don't need it", that's not an answer to my question. I wondering if there's a reason for it's omission from most magneto designs... I also understand that if you are using one to drag race, you probably don't need an advance curve...
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They don't need one on the track because you never use the motor below 3500 rpm.

But they are much nicer on the street with an advancer. I have used the Lucas advance mechanism on the JH mag very successfully. Of course that was with the rear mounted mag which didn't last.

I ended up going back to the old Lucas mag which still works fine. Jim
 
What I'm wondering is does a magneto affect it's own delay by turning slowly? I'm talking about it's building the potential to spark. If not, then here is the question: if you fixed the advance of an electronic ignition at 28 degrees btdc would it perform as a magneto does? Perfectly ok at idle? Or would you get pre-ignition? Obviously magnetos work just fine like this. So is a motor with a magneto just performing poorly on the top end so it doesn't self destruct on idle? And if that's not the case, why do we need such fancy advance curves with electronic ignitions? Could it be that setting a magneto with fixed advance to not preignite at low rpm, the mag spark gets so hot at high rpm you don't need so much advance? Finally, has anyone done a real test on a dyno with mag then electronic ignition on the same motor? If the mag solves some of these problems I'd take a good mag in a heartbeat. If not, I'm sticking with electronic.
 
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