Joe Hunt mag. Pro’s and Con’s for a tuned motor...

As the title suggest, I’m interested in views on use of a Joe Hunt (or other) mag on what is basically a race motor.

It’s a Maney 920, Maney cam, Stage 3 head, and will be around 10.5:1 CR. It’ll have a Maney 2:1 pipe and FCR carbs.

My ‘go to’ position would b to fit a Tri Spark with cNw coil as I know how well this set up works.

But the bikes not gonna have lights, so eliminating charging system, battery, wiring, etc has got my interest.

I know Ashley has had one on his 850 for about 300 years and a million miles and loves it. But I’d like to hear from people who have used one on a motor similar to mine.

I’d also appreciate any learned opinion on the operational pros and cons, I don’t want to get into a discussion about how much they stick out etc, but more how good is the spark for a big bore, starting on a big motor, etc.

Thanks in advance...

Fast Eddie said:

As the title suggest, I’m interested in views on use of a Joe Hunt (or other) mag on what is basically a race motor.

It’s a Maney 920, Maney cam, Stage 3 head, and will be around 10.5:1 CR. It’ll have a Maney 2:1 pipe and FCR carbs.

My ‘go to’ position would b to fit a Tri Spark with cNw coil as I know how well this set up works.

But the bikes not gonna have lights, so eliminating charging system, battery, wiring, etc has got my interest.

I know Ashley has had one on his 850 for about 300 years and a million miles and loves it. But I’d like to hear from people who have used one on a motor similar to mine.

I’d also appreciate any learned opinion on the operational pros and cons, I don’t want to get into a discussion about how much they stick out etc, but more how good is the spark for a big bore, starting on a big motor, etc.

Thanks in advance...

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Any magneto on a race motor for road racing is a good option, if you are using methanol fuel. There is much less that can go wrong. However If I was using petrol, I would use a programmable ignition system. Using an advance curve along with fine carburettor tuning has the potential to give more power. For road use - does it really matter as long as it keeps working ?

I just managed to find a thread about how much work is involved in fitting a mag behind the cylinders, I didn’t realise the cases need welding and re-machining. I think I’ll discount that option.

Timing case mounted is still an option, but this is a track bike, and sliding off is easy to do on the track. I wouldn’t want a simple slide to result in trashed crank case half or bent cam etc...

Since it will be a track bike, couldnt you eliminate the charging system, use a small/medium sized li ion battery and then when you go back to the pits stick it on a charger to keep it topped up? The wiring would be drastically simpler with that, and you wont be lugging around the stator/rotor or have a lump sticking out.

My first Joe Hunt maggie that I brought for my 1981 Triumph Thunderbird came from a mate who was running it on his very hot race Triumph very high compression motor, he had the JH off it getting it rebuilt, the JH work great on his bike when it was going his problem was to much compression and blown motors and the fact having the JH sticking out the side.
What Don did was to mount the JH off the side of the motor using soft mounting bolts so if he did go down on the JH side the bolts will snap off and the JH will slide away from the bike, he did a few race meets with this set up, the bike never raced again and he sold me the JH for the price of the rebuild, it was on my Triumph for 9 years and a lot of miles without any problems at all with it.
The JH maggies are well built and strongly made and will withstand a bit of punishment and the weakest part is the top brakelite cover but if your racing you should have a spare just in case.
I had to lay my Norton down one day when a car turned in front of me without indicating and the maggie slid on the road the plug leads fused into the bakerlite cover and tore off the plug leads, the plug ends were so fused in the cover from the heat of sliding down the road, the JH servived but the cover now sits on the wall of shame, I now run soft bolts on my mounts.

Ashley

Hi

Kickstart Eddie?
Do electrix world do one of their charger/ignition systems?
I still run interspan & charge it off the van battery. TT coils Fred tells me 2 hours running time. Mine are very old & I fully charge it then top up before each race.
I will need to look at the pvl bits I have one day. With a 23mm belt as per CNN's electric start system there would be room to fit the rotor.
Chris

Fast Eddie said:

I just managed to find a thread about how much work is involved in fitting a mag behind the cylinders, I didn’t realise the cases need welding and re-machining. I think I’ll discount that option.

Timing case mounted is still an option, but this is a track bike, and sliding off is easy to do on the track. I wouldn’t want a simple slide to result in trashed crank case half or bent cam etc...

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Use soft mounting bolts on the JH if you do go down on that side the soft bolts will sheer off and the JH will slide away from the bike and servive without major damage.

Ashley

ashman said:

Use soft mounting bolts on the JH if you do go down on that side the soft bolts will sheer off and the JH will slide away from the bike and servive without major damage.

Ashley

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Soft bolts is a good idea Ashley. What do you use exactly?

Gortnipper, yes that’s an option... but if I was going ‘total loss’ I think I’d go Interspan like Chris mentioned. I’ve run Interspan on 3 race bikes and don’t recall ever having a single issue.

Chris, that Electrexworld stuff... waddya know about it? Frankly it looks a bit Micky Mouse to me but I’ve no experience with it at all...

A lot of boys on the crmc forum swear by them. TZ mainly. I think Dean had one built for his 400 kwak twin. Sensor did not turn on until I sensed the engine turning. He has variable programming.
Chris

I just used the bolts that came with the JH maggie kit the bolts were not harden bolts, as well with the kit the hex drive shaft was very soft and was showing sign of wear in a short time so I replaced it with a same size allen key which is the same hex, the allen key is a lot harder and you will get 3 spare drive shaft from one allen key, I also have a few other secrets up my sleeve if you decide to go the JH way.
Which ever bike the JHs are set up for they will perform and give good service life if set up right and hanging off the side they can't get any simpler than that run straight off the cam.

Ashley

I used a Joe Hunt mag on my racebike for a few years. When it worked right which was most of the time, it was a divine miracle of magic electricity from heaven; when it was giving me problems it was nightmare from hell. Although most of the issues I had with were a bad connection, broken inner coil lead and the most annoying was when we broke the inner shaft driving it from the timing case- sometimes it would hook up and sometimes it wouldn't before we finally realized what was going on after numerous on track strandings.
Overall it worked well, was easy to start and not having to worry about a battery was convenient blessing. When I had the broken inner shaft racing at Mid-Ohio one year, I rigged up a Boyer electronic I had in my tool box and it was interesting to run the points spark Joe Hunt and an electronic ignition back to back on the same day- I could feel a couple extra HP from the electronic and smoother running at high revs. After that, I binned the joe Hunt and have just run a Boyer ever since although the idea of an electronic magneto does interest me...
Here is what the mag looks with the cover off, we had it tucked in behind the cylinders and here is what the inside of the timing case looked like with an extra chain and drive sprocket Herb added.

Doug, that's similar to the experience Dave Wildman had with his big bore Triumph sidecar racebike at Westwood in the early 80s.
He had a Lucas racing mag fitted and the bike went very well.
His sidecar man convinced him to try Boyer, which would have been the old analog, with what some consider the bad power curve.
The engine pulled an extra 300 rpm on the straight plus pulled up over the mountain with a similar boost.
The KVFTT went on the shelf!

Glen

Chris said:

A lot of boys on the crmc forum swear by them. TZ mainly. I think Dean had one built for his 400 kwak twin. Sensor did not turn on until I sensed the engine turning. He has variable programming.
Chris

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Interesting Chris, thanks.

Doug MacRae said:

I used a Joe Hunt mag on my racebike for a few years. When it worked right which was most of the time, it was a divine miracle of magic electricity from heaven; when it was giving me problems it was nightmare from hell. Although most of the issues I had with were a bad connection, broken inner coil lead and the most annoying was when we broke the inner shaft driving it from the timing case- sometimes it would hook up and sometimes it wouldn't before we finally realized what was going on after numerous on track strandings.
Overall it worked well, was easy to start and not having to worry about a battery was convenient blessing. When I had the broken inner shaft racing at Mid-Ohio one year, I rigged up a Boyer electronic I had in my tool box and it was interesting to run the points spark Joe Hunt and an electronic ignition back to back on the same day- I could feel a couple extra HP from the electronic and smoother running at high revs. After that, I binned the joe Hunt and have just run a Boyer ever since although the idea of an electronic magneto does interest me...
Here is what the mag looks with the cover off, we had it tucked in behind the cylinders and here is what the inside of the timing case looked like with an extra chain and drive sprocket Herb added.

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Doug, I couldn’t really ask for more specific feedback than that. Thank you.

As good as a mag sounds, you and Glen and others do make EI sound better!

On balance, I think I’ll stick with the EI. Just dunno which yet !

As you don’t want lights or battery, you need a self-generating EI .

There's a recent thread on Britbike about someone having a very bad experience trying to have a mag serviced by JH. Reviews of customer relations dealings must be taken with a grain of salt, but...

I've got a JH mag on my Triton and it works very well. Easy to adjust and holds its adjustment.

Bernhard said:

As you don’t want lights or battery, you need a self-generating EI .

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I agree, trouble is I don’t have any first hand experience of any such systems. And I know from prior experimentation that sometimes systems that work well in compact, clean, modern combustion chambers don’t fair so well in something like a 920 Norton combustion chamber.

So, I’d only venture into this direction following someone’s lead rather than be the vanguard into the unknown.

Guess I’m just a pussy !

Fast Eddie said:

I agree, trouble is I don’t have any first hand experience of any such systems. And I know from prior experimentation that sometimes systems that work well in compact, clean, modern combustion chambers don’t fair so well in something like a 920 Norton combustion chamber.

So, I’d only venture into this direction following someone’s lead rather than be the vanguard into the unknown.

Guess I’m just a pussy !

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Nigel ,I wonder if Steve or Minnovation have any of his EI kits. As you are not fitting an alternator surely this would be the way to go for you are not getting the variations induced by the camshaft. Would it be difficult to modify a basic pazon or boyer to run off the crank ? Or perhaps one of them would advise on a suitable single cylinder unit