Joe Hunt magneto

No matter at what speed they spin the Joe Hunt will produce a great big spark and the faster they spin the bigger the bang, mine is set at 28 degrees full advance and is perfect riding around the suburbs at slow speed or open it right up at high speeds it just goes as long as carbs are set in tune, I have just gone back to my old Amal carbs and the Norton is running great with the Joe Hunt from low down to fully open without missing a beat or any hesitation at all.
This is my second British bike with running JH's my 81 Triumph Thunderbird for 9 years with lots on kms clocked up on it without any problem at all with the JH, it was the 2 rare earth JH and now over 12 years with the JH on my Norton it has the 4 rare earth, will I ever go back to any other ignition system, no.

Ashley
 
There isn't one.
Tractor engines just plod along, less than 2,000 rpms
My understanding, and I know for a fact, is that motors respond better when the spark moves down the cylinder as the piston is coming up Onthe compression stroke. That’s why its called advance, I suppose. It would be great if someone made one with a centrifugal advance system that was adjustable using springs, like the Delco Remy distributors of old. Not really sure if or how that would work. But lack of a centrifugal advance leaves me on the sidelines.
 
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My understanding, snd I know for a fact, is that motors respond better when the spark moves down the cylinder as the piston is coming up Onthe compression stroke. That’s why its called advance, I suppose. It would be great if someone made one with a centrifugal advance system that was adjustable using springs, like the Delco Remy distributors of old. Not really sure if or how that would work. But lack of a centrifugal advance leaves me on the sidelines.

Joe Hunt magnetos for flange mounting behind the cylinders can be fitted with the Lucas AAU which is a centrifugal advance device giving a 24 degree advance at the crankshaft.

But you are SOL for a centrifugal advance system fitting one on the camshaft.

Slick
 
Joe Hunt magnetos for flange mounting behind the cylinders can be fitted with the Lucas AAU which is a centrifugal advance device giving a 24 degree advance at the crankshaft.

But you are SOL for a centrifugal advance system fitting one on the camshaft.

Slick
Thanks.
 
Not sure what you mean by this.
How can the spark move down the cylinder?
Maybe something new for me.
Imagine that as the piston starts moving up on the compression stroke, the spark starts coming on sooner to initiate the combustion. The spark is “advancing” giving a longer combustion event. In other words, the gas is starting to burn when the piston is further down the cylinder when the motor is accelerating and can use it. The opposite would be “retarding”, starting combustion later. We like to tune our carburetors with needles and jets. Throw in an adjustable centrifugal advance using weights and springs would give more adjustability to that hot spark for those who like to tweak their ride. I just think spark advance is a good thing. There are a number of videos on Youtube that explain spark advance and its benefits better than I do.
 
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No matter at what speed they spin the Joe Hunt will produce a great big spark and the faster they spin the bigger the bang, mine is set at 28 degrees full advance and is perfect riding around the suburbs at slow speed or open it right up at high speeds it just goes as long as carbs are set in tune, I have just gone back to my old Amal carbs and the Norton is running great with the Joe Hunt from low down to fully open without missing a beat or any hesitation at all.
This is my second British bike with running JH's my 81 Triumph Thunderbird for 9 years with lots on kms clocked up on it without any problem at all with the JH, it was the 2 rare earth JH and now over 12 years with the JH on my Norton it has the 4 rare earth, will I ever go back to any other ignition system, no.

Ashley
28 degrees, and that’s as far as it will go? I bet it would like 35 degrees before 3000 rpm, and that is where an advance mechanism would be useful. I don’t know what a Norton motor can use to reach max power, but am curious what the optimum timing specs are. BTW- I used your vinegar idea for cleaning up my Amals, along with some steel wool and they really look great now. Thanks for that suggestion.
 
28 deg is the ideal advance for a Norton with a high compression/small combustion chamber as dyno proven by many top Norton tuners. The more efficient your combustion (tight squish band etc) - the less advance you need or want. Low compression lower performance Nortons can use 31 degrees advance and maybe more. The Magneto I use has a centrifugal advance (no kick back) and it reaches full advance quicker than the modern CDI units currently on the market. This means that it has more punch and accelleration in the lower end. It also has a hotter spark and sparks on the first revolution unlike most EIs which have to go around a 2nd time before they spark. So you have hotter spark, easier starting and more efficient combustion. Mine is behind the cylinders, is self contained and uses solid copper core plug wires to handle the high energy output.
 
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Imagine that as the piston starts moving up on the compression stroke, the spark starts coming on sooner to initiate the combustion. The spark is “advancing” giving a longer combustion event. In other words, the gas is starting to burn when the piston is further down the cylinder when the motor is accelerating and can use it. The opposite would be “retarding”, starting combustion later. We like to tune our carburetors with needles and jets. Throw in an adjustable centrifugal advance using weights and springs would give more adjustability to that hot spark for those who like to tweak their ride. I just think spark advance is a good thing. There are a number of videos on Youtube that explain spark advance and its benefits better than I do.
I get you now - I understand changing ignition advance. It was your description that had me scratching my head.
I actually think that the ability to change the advance "curve" with modern EI systems is superior to the spring/weight as, with those, you are subject to potential variation in spring characteristics (spring to spring and over time) as well as things like pivots not being lubricated.
Cheers
 
28 deg is the ideal advance for a Norton with a high compression/small combustion chamber as dyno proven by many top Norton tuners. The more efficient your combustion (tight squish band etc) - the less advance you need or want.
I have used this argument with Triumph owners over the years - 38 degrees vs 28 - are you sure you don't have a steam engine there?
What magneto do you run?
 
I get you now - I understand changing ignition advance. It was your description that had me scratching my head.
I actually think that the ability to change the advance "curve" with modern EI systems is superior to the spring/weight as, with those, you are subject to potential variation in spring characteristics (spring to spring and over time) as well as things like pivots not being lubricated.
Cheers
Yes... more stable perhaps, but aren't most also just RPM dependant? No regard for throttle opening/engine load etc..
A good compromise though, and possibly way more expensive to improve..
 
As I have said before I have been running JHs on 2 bikes without a retard set at 28 degrees on the Norton can't remembered what the Triumph was set on but would have been the same setting as points, both bikes always started first kick, ran good in all running situations through the rev range, I never took any notice of advance curves as was set and forget. My old 81 Triumph Thunderbird did a lot of miles on that bike and did many many travel miles and long distant runs as well a few long distant runs with the wife, the Thunderbird was single Amal carb 650 same size bores as the 750 but shorter stroke it ran well with the older JH for 9 years and I made a mistake selling that bike it was so reliable with the JH.
As for the Norton it has a bit of work done to the motor 850 built for the Featherbed frame,2S cam ports all opened up carbs jetted and open exhaust with very little baffles just enough to give it the right back pressure, this is my hot rod Norton and the JH works so well with all the work I have done through all the rev range.
I have owned the 850 since new and built it in the early 80s been through points and 3 electronic ignitions and so far the JH has been the best for performance wise, ease of starting even on full advance, very reliable and in 12 years on the Norton with 35k miles on it I haven't touched it, still has the original point in it and I just put in a new set of plugs even when the old ones were still looking as good as the day I put them in when I fitted the JH, the plugs run cleaner than it did with all the ignition systems I had run and get great long life out of the N7YC plugs.
I don't get any kick back from starting itand so far the only maintenance I do is every oil change I do on the Norton I pull the front cover off to check the point and to put a few drops of STP on the felt pad for the point arm.
I don't care what anyone says about it hanging off the cam and timing cover it's so simple to set up, no added chain to run or AAU to worry about and it sits out in the cool breeze where it runs so sweet, best thing no big battery to worry about going flat or dying, all self contained, kick and run and both JHs have never let me down in 22 years of running JHs.
I am not technically incline but I do know my own Norton and have built it and all work done by my own hands and as far as I have said the JH is the best for my Norton, might not be everyone's cup of tea but it works for me and looking at the spark in Jim's short clip at such a slow speed and you can understand why I love JH Maggie's and they are so simple compared to the old Lucas Maggie's.
No need to retard it to start first kick for the day will be the biggest kick but after it's run for the day it will fire up with a a lazy kick and before it get 1/2 way on the kicker it be running, my EIs never did that, but my old Boyar was still running after 32+ years on my Norton and back in the late 70s Lucas's Rita (failed within 12 months) and Boyar were the only EIs on the market for the Norton (first Boyar failed a week after the great fire of 82 100 miles from home) and the replacement Boyar was still going when I installed the JH so was lucky but went through a few batteries in those years and a few coil failures as well.
This is just my look of things with my experience with running JH Maggie's on both my British bikes and I am a true believer of JH Maggie's no matter where they sit and I am sure Jim is as well.

Ashley

Joe Hunt magneto
 
28 deg is the ideal advance for a Norton with a high compression/small combustion chamber as dyno proven by many top Norton tuners. The more efficient your combustion (tight squish band etc) - the less advance you need or want. Low compression lower performance Nortons can use 31 degrees advance and maybe more. The Magneto I use has a centrifugal advance (no kick back) and it reaches full advance quicker than the modern CDI units currently on the market. This means that it has more punch and accelleration in the lower end. It also has a hotter spark and sparks on the first revolution unlike most EIs which have to go around a 2nd time before they spark. So you have hotter spark, easier starting and more efficient combustion. Mine is behind the cylinders, is self contained and uses solid copper core plug wires to handle the high energy output.
This sounds great. Sounds like a specialized unit installed by someone who knows what they are doing. Regarding the amount of advance that a Norton motor can handle, are you saying that the JH magneto similar to what Ashman is using will give the ideal setting and doesn’t need an advance curve? I am only familiar with high compression V-8s that can handle 36 degrees all in by 3000 using spring controlled centrifugal advances, not with Norton timing other than installing an EI. The magneto looks intrigueing to me, but not without an advance curve unless its not necessary. Thanks.
 
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28 degrees, and that’s as far as it will go? I bet it would like 35 degrees before 3000 rpm, and that is where an advance mechanism would be useful. I don’t know what a Norton motor can use to reach max power, but am curious what the optimum timing specs are. BTW- I used your vinegar idea for cleaning up my Amals, along with some steel wool and they really look great now. Thanks for that suggestion.
The Lucas AAU has a 12 degree range which gives 24 degrees at the crankshaft. The Lucas AAU could be modified by dremel grinding the stop to give 15 degree range or 30 degrees at the crankshaft. To this, you can get more total advance by setting a static advance with the initial set up. For example, I have set my total advance to 30 degrees, 24 of which is due to the centrifugal action of the AAU, the other 6 is a static preset.

BTW .... a JH mag hung off the cam end ala Ashley, can be fitted with a manual retard lever for starting, but Ash says it is not necessary.

Slick
 
As I have always said never a problem starting first kick every time set at full advance, as long as carbs are tuned right, the first kick for the day involves a full big kick as I don't run chokes on my Amals and its winter here, but once its been started it fires up with lazy kicks even sitting on the seat to kick it, I been running PWK carbs for 12 years since I had the JH but have just gone back to my old Amals and still dialing them in have the Norton running great but the first start for the day still needs a bit of tinkering or its just me getting use to Amals again, the old Amals seem to be running a bit better than the PWK carbs, not sure why I changed too PWKs 12 years ago, but the left Amal had a block pilot jet when I pulled them apart for cleaning before reinstalling them, could have been the reason I replaced them.
I have never used a timing light to set my timing, I set the JH to static timing at 28 degrees and if I get any kick back when kicking I slightly retard the timing ever so slight till no kick back at all, I been timing my Norton this way ever since I have owned it from new and works for me.
At the moment I been rewiring my Norton and getting all the lights and a battery set up working, I been running the Norton with a electronic recifer/battery eliminator but now going back to original Zener and recifier and small battery for brighter lights, not that I use lights during the day.
2 weeks ago when out on the Norton the JH, Amals were running great all through the rev range but the first kick for the day was a bit of spit through the carbs and took 3 kicks to fire it up cold but once started its firing first kick every time so am very close, just a bit too much fuel for the first kick still got to get use to using Amals again.
Hopefully will be out on the Norton on Sunday, just got to wire in the new headlight/horn switch and test the wiring and put acid in the new battery.
2 weeks ago was the first run with the Amals had a small screw driver with me to do minor adjustments while out and about and was out running around for 1/2 the day stopping at mates places visiting here and there so gave the carbs a good workout and very happy with how its going I haven't touched the JH settings at all, I am running K&N air filter but they are getting old been on the Norton since 1982 so might renew it soon, but they always get a good clean when doing an oil change and service.

Ashley
 
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The Lucas AAU has a 12 degree range which gives 24 degrees at the crankshaft. The Lucas AAU could be modified by dremel grinding the stop to give 15 degree range or 30 degrees at the crankshaft. To this, you can get more total advance by setting a static advance with the initial set up. For example, I have set my total advance to 30 degrees, 24 of which is due to the centrifugal action of the AAU, the other 6 is a static preset.

BTW .... a JH mag hung off the cam end ala Ashley, can be fitted with a manual retard lever for starting, but Ash says it is not necessary.

Slick
Ok, thanks.
 
The behind the cylinders mag (Atlas & Domni style{) has a mechanical centrifugal advance. The side mount at the timing points cover doesn't have this advantage (hence the retard lever). The ARD was a much smaller mag that mouted on the points cover (with remote coils). But the ARD didn't have an advance either and is no longer in production.
 
The behind the cylinders mag (Atlas & Domni style{) has a mechanical centrifugal advance. The side mount at the timing points cover doesn't have this advantage (hence the retard lever). The ARD was a much smaller mag that mouted on the points cover (with remote coils). But the ARD didn't have an advance either and is no longer in production.
Thanks for explanation. Do you think the side mounted JH offers less performance, or is somehow hindered, than an ignition with an auto advance system?
 
Once the engine is running, I as well as most if not all racers want full advance at all RPM for best performance. The advance/retard is so the motor is retarded when you kick start it (to avoid kickback). Back when I was using a Boyer electronic unit for racing I installed a pair of resistors to cut off the advance/retard so it was more fully advanced at lower RPM for more drive out of the turns. This Boyer resistor technique is laid out in my race manual. I haven't tried it on other EI systems.
 
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