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Magnetos or E.I.?

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Just wanted to share this with my fellow NOCers on the subject of Magnetos or Electronic ignition.

Reading the September Classic Bike article on the Peter Lodge ES2* that lapped the IoM at 110.312 mph and which develops "around 60 BHP with over 40lb.ft of torque", he says
"I have always run SR1 Twin Spark magnetos or similar....last year we thought we could do better with a modern hi-tech electronic system- it did one lap before a misfire set in."
"The magneto's back on now- you have to ask yourself why all the big Top Fuel dragsters still use magnetos. And 40 amps is the reason for it."

*Now, I take my hat off to the man, who is clearly a highly skilled engineer far in excess of this simple spanner- wielder, but it is a bit of a stretch to call this incredible machine an ES2.

All the cycle parts are Manx replica. 6-speed gearbox, belt driven through a Surflex speedway clutch. The engine build includes: steel crank, with 78mm (and later 75mm) short stroke instead of 90mm; Carillo con-rod, 12:1 Arias piston. Peter has cast his own crank-cases, twin-plug head with massive extra finning to prevent over-heating, Manx-type Nikasil lined barrel. He's even cast the rocker arms himself. Add in lightened (vernier?) camshaft gears, and it now shares very little of the ES2 Cafe racer he built as an apprentice. But the oil pump looks to be original- and it is still "just" a pushrod single!

A remarkable machine.

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Don't aircraft still use magnetos? An electronic system needs a generator, regulator, fuse, ignition switch, associated connection wiring with lots of terminals...
A magneto is a simple, largely mechanical, device with one external connection from the instrument to the spark plug.  They do wear out eventually and they do need occasional lubrication and attention to a contact breaker but they are extremely reliable until they are old.
The most reliable Norton must surely be the 16H?  With a magneto.

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Replacing a magneto with electronic ignition means a system that relies on a generator.

In my experience, the Lucas magneto is a much more dependable piece of kit than their dynamo with associated ancillaries.

Aircraft use two magnetos so that's sort of cheating a bit !

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I had to give up on the K2F magneto, because the available new points sets are so poorly made that they fall apart in service.

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EI does NOT rely on a generator, it relies on a battery. When the battery goes flat, then you need a generator to get home. A lot of racers run on total loss batteries, ok for a 1hr race-change battery. But despite being the lover of EI, and being the last remaining guru for Lucas Rita EI is NOT the answer to a failing/worn magneto. Aircraft with two mags correctly set up is obviously a good way to go.
The problem with the apparent answer to a dodgy mag-of EI is that most of you do not see ALL the ramificatiions, cost, battery, dynamo, charging/regulator, ignition switch, extra wiring, housing assembly, different details for ignition timing.

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Powering electronic ignition with a Lucas E3  dynamo or 6V alternator is dodgy.

Aeroplanes don't just use dual magnetos: they use dual good magnetos!  Fitting a British motorcycle magneto to an aero engine would be evidence of attempted murder.

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Mag vs.EI? Surely this 'argument' is driven by what 'technology' you are most comfortable with? If you have had magneto's for ever, you will be more than comfortable with them. If you've only ever had EI then you will see these as best.
Same argument applies for zener diodes vs a reg/rec unit or soldered vs crimped connectors on your wiring. No real right or wrong whichever you prefer. 

As for Michael's initial comment about reverting to a Magneto, under racing conditions a mag should be working in an optimum state, ie. spinning at speed- not trying to provide a spark at kickstart speed.  One failure example on one home made racer doesn't mean all EI systems are bad, more likely the parts used weren't properly specified,matched or mounted properly in the first place.
Fit what YOU are happy with, and let's not knock those who see things differently!

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...well and truly stirred!

Good to see all the comments in favour of preferred igniter! As always, something learned in the round.

At least nobody advocated trembler ignition. Whatever that was! Maybe see one in evidence at the NMM Norton Day this weekend....

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Have bikes with magnetos, points, EI, CDI, transistors. Rarely have any problem with any of them. Never found any of them better. Only magneto drawback might be when the repair shop gurus retires there will probably be no young guys to replace them. And lack of quality spare parts. Probably same with other kinds of ignitions too. On race bikes a small inconvenience with battery charging. On road bikes points cleaning, gap adjustment and lubrication takes some time. But keeping batteries charged also takes time. The simplicity of magneto wiring, one lead to the spark plug and maybe a kill button wire is advantage. Even an electrical idiot can figure it out.

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As some of you know I used to sell Boyer Bransden kits/parts, some years ago a chap came to me for a BB system where he could fit a pickup direct to the flywheel, I said what bike? not bike-car,
An 18** french thing. So I asked what was the original ignition system-hot tube! (me being a smart pants) said 'well you don't get any advance with that system'  'you will do with the BB' 'oh yes we do get advance, we turn the flame up so the tube is hotter further down!'  Gulp.
Hope you find a trembler ignition Mike let us know.

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Yes, a longer tube advances the timing, because the mixture is more readily shoved into it by compression.

The winner has got to be carrier flame ignition though.

 



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