Joe Hunt reliability test

Fast Eddie said:

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

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One of the items on the list is a large new tube of red RTV silicone.

They are opposite rotation, so likely an opposite rotation set of points. I DO NOT KNOW, but that might be all, unless the cam profile is not the same curvature on opening and closing

I cannot remember whether the cam in my Norton motor rotates backwards or forwards, Isn't there an intermediate gear in the Norton motor ? When I work on a motor, I usually do it without thinking, unless I am forced to re-engineer something. My brother is currently struggling with a Joe Hunt Magneto on a 1000cc Vincent. It is set up to cope with the different angle between the cylinders. It turned out that it had a stuffed coil.

grandpaul said:

One of the items on the list is a large new tube of red RTV silicone.

They are opposite rotation, so likely an opposite rotation set of points. I DO NOT KNOW, but that might be all, unless the cam profile is not the same curvature on opening and closing

Click to expand...

I cannot find the source, but AI says:

To convert a Joe Hunt Magneto from counterclockwise (CCW) to clockwise (CW) rotation, you must replace the internal cam and re-time the magneto to match the new rotation.

Here’s a breakdown of what’s involved:

Conversion Steps for Joe Hunt Magneto (CCW to CW)

Replace the Cam

The cam inside the magneto is rotation-specific. A CCW cam will not function properly in a CW setup.

You’ll need a clockwise-specific cam from Joe Hunt or a compatible supplier. This cam controls the timing of the points opening relative to rotor position.

Verify Rotor Compatibility

Most Joe Hunt magnetos use a rotating magnet (rotor) that’s symmetrical, but confirm that your rotor is compatible with CW rotation.

If not, you may need a CW-specific rotor or re-polarize the magnet.

Re-time the Magneto

With the CW cam installed, rotate the magneto clockwise until the small lobe on the cam is just about to open the points.

At this position, reinstall the magneto housing onto the base while maintaining cam alignment.

Check Drive Coupling

Ensure the drive coupling (hex or gear) matches the CW rotation of your engine’s camshaft or timing gear.

If the magneto was previously driven off a CCW camshaft, the drive gear may also need to be reversed or replaced.

Test Spark Timing

Once installed, verify spark timing with a timing light or static method.

Adjust the base rotation of the magneto to fine-tune ignition timing.

Jim keeps saying the JH magnetos run pretty good set up behind the motor with all the heat, but he also has had problems with condensers that JH use, maybe caused from heat, but the JH running off the side of the timing cover I have never had any problems with the JH condensers as my JH runs in the cool air flow, of course when you do a tune up the tune up kits from JH have point, condenser and new plug leads as part of the tune up kit, but I been running my JH on my Norton now for 15 years, but I have only replaced the condenser after a slide down the road from an accident where the magneto front cover and condenser was damaged but that was the first week of installing the JH, so the condenser and point have been running for the 15 years and over 35k miles without missing a beat, as I have said I pull the front cover off the magneto every oil change to inspect the point and lube the felt for the point cam, when my Norton is running good and starting first kick I leave it well alone.
My mate use to file his point when it had build up on contacts but filing them upsets the hardening of the points and the point will wear quicker and will need replacing after a short time after, I just clean mine with a bit of Metho if they need cleaning, I never use a file or sandpaper to clean my point's.
Funny story, one day while parked up a group of bikers were checking out my Norton and one asked what the thing was sticking out the side of my motor was, I told him it's a anti thief device, what, yes if I catch anyone trying to steal my bike or stuff around with it those leads be connected to their balls and I give it a few kicks and watch their eyes pop out, his mates knew what it was and they pissed themselves when I said that.

Greg hit the nail on the head with changing the direction of the Hunt magneto, back in the early 80s I had an 81 Triumph Thunderbird, my mate Don who got me into Nortons had a Tritan race bike running an older JH magneto but he was worried about crashing it sticking out the side, he just had it rebuilt and he sold it to me for the price of the rebuild, I was going to set it up to run on my Norton but I had ignition problems on the Triumph so I ended up installing it on the Triumph and for 9 years and 250k kms it ran perfectly till I sold it, biggest mistake I ever made selling that bike.
Compared to the old Lucas magneto's the Joe Hunt magnetos are so much easier to work on everything is just under the front cover, they produce a bigger hotter spark and always fire up on a one kick every time if your carbs are tune right, my first cold kick for the day I give it a full swing on the kicker once it fired up for the day it always fires up on 1/2 a swing on the kicker or from a lazy kick, I have no problems sitting on the seat and just give it a kick and it will fire up, even with a blocked pilot jet it will fire up on one cylinder on one kick as I found out when I reinstalled my old Amal carbs and they weren't even tuned right.
Al a new coil from JH is cheap just go to their web site to order and shipping to Aus only takes about 9 days through normal mail, I have had no problem dealing with Joe Hunt.
Just turning a JH magneto by hand slowly will produce a big spark with a cracking noise, I was once riding home and just past my mate place when my Norton had a bit of a miss fire looked down at the magneto and one of my plug lead had popped out and the spark was jumping 2 to 3" as I was so close to home just around the corner and up the hill I kept going the bike had a miss fire but was still firing on both cylinders with that spark jumping to the cover, I could see the spark clearly, I now run a bridge between the leads and has stopped the leads from popping out.

Ashley

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...

I just went to first of others to see this bonnie here in Toronto , but chopperized out , very rusty , with the J.H.
Maggie all rusty all over , no ownership , siezed pistons , single carb , 5 speed motor , apehangers .
Many other badges , tanks ,frames, etc, the owner showing but not selling . Typical tip explorer situation . Did not want to talk money .

marshg246 said:

I cannot find the source, but AI says:

To convert a Joe Hunt Magneto from counterclockwise (CCW) to clockwise (CW) rotation, you must replace the internal cam and re-time the magneto to match the new rotation.

Here’s a breakdown of what’s involved:

Conversion Steps for Joe Hunt Magneto (CCW to CW)

Replace the Cam

The cam inside the magneto is rotation-specific. A CCW cam will not function properly in a CW setup.

You’ll need a clockwise-specific cam from Joe Hunt or a compatible supplier. This cam controls the timing of the points opening relative to rotor position.

Verify Rotor Compatibility

Most Joe Hunt magnetos use a rotating magnet (rotor) that’s symmetrical, but confirm that your rotor is compatible with CW rotation.

If not, you may need a CW-specific rotor or re-polarize the magnet.

Re-time the Magneto

With the CW cam installed, rotate the magneto clockwise until the small lobe on the cam is just about to open the points.

At this position, reinstall the magneto housing onto the base while maintaining cam alignment.

Check Drive Coupling

Ensure the drive coupling (hex or gear) matches the CW rotation of your engine’s camshaft or timing gear.

If the magneto was previously driven off a CCW camshaft, the drive gear may also need to be reversed or replaced.

Test Spark Timing

Once installed, verify spark timing with a timing light or static method.

Adjust the base rotation of the magneto to fine-tune ignition timing.

Click to expand...

Thanks Greg !

marshg246 said:

I cannot find the source, but AI says:

To convert a Joe Hunt Magneto from counterclockwise (CCW) to clockwise (CW) rotation, you must replace the internal cam and re-time the magneto to match the new rotation.

Click to expand...

That's what I thought, the cam is not symmetrical.

I don't think you have to change the cam unless its non-symetrical. The Harley JH mags are non-symetrical and I think the cam in an intregal part of the armature on the JH mags. To change mag rotation all you have to do is switch out the points for points that fit on the opposite side. I've have mags delivered with the wrong points in them. Switching points, points plates and moving the condenser to the other side is not that big a deal. Its a small investment and I'm pretty sure it works. If not then you haven't lost much.

The Norton and preunit triumph mag are the same #1278 (see below). AI is often helpful but in can also be dead wrong and give conflicting answers - especially about old brit bikes.



See the #1278 mag diagram below and the one piece cam/armature

I have been on this site for a long time and have read so many threads on failed EIs or failed pick ups and low battery failures etc and some who take a spare pick up when out for a ride, I have also had 2 EI s fail on me but were in the late 70s my first Lucas Rita failed within 12 months it just died without any warning replaced with a Boyer but in 82 it failed a week after the great fire and 100 miles from home the black box failed from the fire, but the replacement Boyer was on the my Norton for 32 years and was still going strong when I replaced it with the Joe Hunt, but so many complained about Boyer's with kick back, but in the 32 years I only ever got 2 bad kick backs from my unit.
Some had problems with Trispark units and replaced a few times as well other EIs but in the 25+ years of running with JH magneto's I have never had one let me down, not having to worry about a flat battery, easy to maintain, first kick every time when cold, no need to retard to fire up, set right they don't kick back at full advance when kicking, the quicker they spin the bigger the spark, long life from my plugs without any carbon build up on the electro, from opening the throttle instant get up and go and keeps going till you back off, in 50 years of owning my Norton its the best it has ever ran since I put the JH on and even better now I gone back to my old Amals, they both work so well together.
Would I go back to EI, not in my life time, am I happy with my JH magneto, fu cking yes.

Ashley

The JH may have a cleverly ground cam with the opening ramps different from the closing ramps, or it may not: I don’t know, but it would make a difference to the job of reversing the rotation.