Joe Hunt reliability test

Here's a boring video of a JH mag being tested for 25 min at 7000 eng RPM. The mag heats up but never misses.

jseng1 said:

Here's a boring video of a JH mag being tested for 25 min at 7000 eng RPM. The mag heats up but never misses.

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What are you using to determine "never misses"? There are lot of anomalies, especially on the left side, and unless you have a high-speed camera you're not showing I don't see how you know there are no misses.

Just to be a PITA : Open air testing has very little to do with what happens in a cylinder under compression with fuel and air present at higher RPMs.

jseng1 said:

Here's a boring video of a JH mag being tested for 25 min at 7000 eng RPM. The mag heats up but never misses.

Click to expand...

I'd always been told that to fully test a magneto it has to run at low speed?

baz said:

I'd always been told that to fully test a magneto it has to run at low speed?

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With good carbs properly setup and Tri-Spark, a cold Commando will idle (just barely) at 700 RPM (350 cam RPM). So, it would be interesting to see with the magneto turning are at 350 RPM.

this is me testing a Lucas k2f that works perfectly until it gets hot
IE when it's bolted to an engine it runs for about 20 minutes before it falters and cuts out due to condenser trouble

baz said:

this is me testing a Lucas k2f that works perfectly until it gets hot
IE when it's bolted to an engine it runs for about 20 minutes before it falters and cuts out due to condenser trouble

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Are those the old resistor plug caps? I was always under the impression they are not needed with a magneto. Well, I never used them when I had a K2F on my Norton. The K2F still works spinning it by hand, so it wasn't hurt not using resistor plug caps.

Schwany said:

Are those the old resistor plug caps? I was always under the impression they are not needed with a magneto. Well, I never used them when I had a K2F on my Norton. The K2F still works spinning it by hand, so it wasn't hurt not using resistor plug caps.

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Yep they are resister caps and this video is from years ago but it doesn't seem to make any difference
It's a magneto removed from my A10 when it was playing up ,I bought a recon mag and aar unit and it's been fine ever since
I ran this mag again in my lathe a few months ago with just the HT leads cracking off to the mounting plate
It's got a fierce spark but after 20 minutes or so with a hot air gun on it to simulate engine heat it started to falter and then stopped sparking completely
I've bought a bright spark condenser pack for it but in the meantime I've bought a Lucas sr2 mag that I plan to use on my atlas engine

Schwany said:

Are those the old resistor plug caps? I was always under the impression they are not needed with a magneto. Well, I never used them when I had a K2F on my Norton. The K2F still works spinning it by hand, so it wasn't hurt not using resistor plug caps.

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Thinking about this
When this mag was on my A10 it had champion plug caps so I'd assume non resister type

I been using JH maggies on 2 British bikes for 25+ years the first one a 2 rare earth on the Triumph and on the Norton a 4 rare earth magnets, they both idle perfectly and also can run all day, but both mine were mounted off the side in the cool breeze and have no problems running all day and on long travels, Idle is just under 1k rpm with my cam why would I let it idle at 700 rpms or lower, it could but why would I, putting stain on the motor, also I can putt around the suburbs at very low revs in a higher gear without bogging down and just open the throttle and the JH just picks up without any hesitation at all and will keep revving as far as I would take it, I get very long life out of my Champion plugs 35K miles I replaced the plugs only just because I removed the PWK carbs and went back to the old Amals so new set of plugs for the tunning, the old plugs still looked like they were only in for a shore time with no sign of wear on the electro.
I have no problems getting long life out of the condenser, I have only replaced the condenser once on the Norton in 15+ years on the bike only because I laid the bike down when a car pulled out in front of me and I cracked the front cover and flatten the condenser which sits just under the cover, tune up kits are cheap from JH comes with point, condenser and new plug leads, so I have 3 kits and 3 spare covers sitting in my parts cabinet so set for life lol.
I very rarely pull the cover off usually when doing an oil change to check on the point and to put a few drops of STP on the point cam felt to lube it, when the bike is running great I leave it alone, my Norton has run the best it ever has since new with the JH and old Amals they just run so well together and to me the Joe Hunts have proven their reliability and the best thing no need for a battery, I only use my small dirt bike battery so I have a bright brake light and bright lights when I do need to use them.
What people think about it sticking out the side directly off the cam, I don't really care, no need to retard it to start first kick even if the carbs are out of tune, not sitting behind a hot motor, its a nice compact unit so why hide it, no extra drive chain or sprocket under the timing cover and no machining needed to install it, bolt straight on with the adapter plate.
Do I love Joe Hunt magneto's, I sure do and so does my Norton.

Ashley

It's nice to be happy with what you have.

ashman said:

...Idle is just under 1k rpm with my cam why would I let it idle at 700 rpms or lower...

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I never said "let it idle". I said that a COLD Commando, properly setup will start and idle at 700. Once warn, it will increase to 1000-1100. If you're starting an idling at around 1000 and it stays there when warm, it truly is a magical bike!

Schwany said:

It's nice to be happy with what you have.

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I must be happy brought the Norton new when I was 17 and did the conversion to the Featherbed in 1980, a lifelong love and lots of good upgrades since, was my first bike I ever built was 22 when I started on the conversion with very little money at the time, I learned from my mate mistakes who got me into Nortons and Featherbed frames Commando's.

marshg246 said:

I never said "let it idle". I said that a COLD Commando, properly setup will start and idle at 700. Once warn, it will increase to 1000-1100. If you're starting an idling at around 1000 and it stays there when warm, it truly is a magical bike!

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It seems all analog / carbureted bikes I've had need a WOT burnout past the neighbors' houses and a few blocks more to get the idle just right.

ashman said:

I must be happy brought the Norton new when I was 17 and did the conversion to the Featherbed in 1980, a lifelong love and lots of good upgrades since, was my first bike I ever built was 22 when I started on the conversion with very little money at the time, I learned from my mate mistakes who got me into Nortons and Featherbed frames Commando's.

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I can't speak for everyone, but it is clear to me that you made decisions your are happy with.

gpzkat said:

It seems all analog / carbureted bikes I've had need a WOT burnout past the neighbors' houses and a few blocks more to get the idle just right.

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I just called the police to keep an eye out for you.

That is funny, and obviously recommended.

My idle goes from won't reliably cold 40F outside for two minutes to about 1000 RPM when warm. I do not have a magneto though, which would make some kind of difference. At least 3lbs of difference.

I had a Hunt mag on my '69 Bonnie special that Hunt restored for me, all new innards, polished housing and new cap.

I used to bet people $100 that it would start on the first kick, and never lost until a down-on-his-luck friend of mine took me up on the bet, at one of the charity bike shows that we used to run. The bike coughed but didn't fire... I HAD FORGOTTEN TO TICKLE THE CARBS!

I happily pulled the $100 out of my shoe (that's how I used to keep emergency money with me) and handed it to him. I was happy to do it; maybe it was subliminal, my memory lapse on tickling the carbs...



Until the day I sold the Bonnie, the Hunt mag NEVER let me down. As far as I know, it never let down the new owner, either...

grandpaul said:

I had a Hunt mag on my '69 Bonnie special that Hunt restored for me, all new innards, polished housing and new cap.

I used to bet people $100 that it would start on the first kick, and never lost until a down-on-his-luck friend of mine took me up on the bet, at one of the charity bike shows that we used to run. The bike coughed but didn't fire... I HAD FORGOTTEN TO TICKLE THE CARBS!

I happily pulled the $100 out of my shoe (that's how I used to keep emergency money with me) and handed it to him. I was happy to do it; maybe it was subliminal, my memory lapse on tickling the carbs...

View attachment 122210

Until the day I sold the Bonnie, the Hunt mag NEVER let me down. As far as I know, it never let down the new owner, either...

Click to expand...

Plus… it screams “Hot Rod” !!

grandpaul said:

I had a Hunt mag on my '69 Bonnie special that Hunt restored for me, all new innards, polished housing and new cap.

I used to bet people $100 that it would start on the first kick, and never lost until a down-on-his-luck friend of mine took me up on the bet, at one of the charity bike shows that we used to run. The bike coughed but didn't fire... I HAD FORGOTTEN TO TICKLE THE CARBS!

I happily pulled the $100 out of my shoe (that's how I used to keep emergency money with me) and handed it to him. I was happy to do it; maybe it was subliminal, my memory lapse on tickling the carbs...

View attachment 122210

Until the day I sold the Bonnie, the Hunt mag NEVER let me down. As far as I know, it never let down the new owner, either...

Click to expand...

That Triumph I'd like to have.

I had Yellow Joe Hunt plug wires on my K2F. That's as close as I ever got to owning a Joe Hunt magneto.

MarshG246 - the anomalies you see are pieces of the exposed end of the silicone cable housing burning off because of the hot spark.

The spark length is set up to be greater than spark plug electrode length to simulate the strain of compression.

Unlike Lucas mags - the JH mag can heat up till its too hot to touch and still fires steady

So… does anyone know what’s involved in converting a JH mag intended for a Norton to fit and run on a Triumph ?