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Oh no it's got a 24 volt coil!

The military waterproof ignition system works well as far as providing spark when it is wet. It has a slight problem when starting of the engine. After installing this system, the starting problem just went away.

The distributor was designed to operate on a 24 volt electrical system. This system provides 24-28 volts during run. Just like the 12 volt systems provide 12-14 volts.

Normal operation of the 24 volt waterproof system on 12-14 volts is fine. In fact the current through the points is reduced and therefore they should last longer than in 24 volt operation.

During start the battery voltage available for starting may drop to under 10 volts. This is because the starter is drawing lots and lots of current. If the coil supplies 100% of the spark voltage at 24-28 volts in normal operation and it only gets 10 volts during start, a little proportion tells us that there is only about 35% of the spark voltage available. This, just when we want extra spark.

I could put in a normal dual battery system but had no where to put the 2nd battery. The cost of the switching device, battery and cables seemed quite high. If all I needed the 24 volts for was to run the coil during start, then a motorcycle battery would work just fine. I went to work and designed a battery switching system to meet the needs. Total cost, including a battery, was under $35.00. A decent battery, alone, would cost more than $65.00!

(as usual click the image for a larger view - then use the back button on the browser to return)

Waterproof - 24 Volt Military Distributor.

Spark plug wires screw on.

Coil is inside, and dwell is available at tach terminal on left.

Motorcycle battery is on the right

"Magic Box" is on the left.

Rubberband is optional and will be replaced with a clamp.

Here is the schematic diagram of the "Magic Box'"

During run the motorcycle battery is charged with the alternator.

A 30 amp fuse is in the system to protect the motorcycle battery.

Contact 1 & 2 go to the DPDT relay that switches the battery.

My system grounds the starter solenoid so I put power to #1 and run #2 to the solenoid.

During start the batteries are connected in series to provide 24 volts.

When the starter is deactivated the relay returns to normal and the batteries are in parallel.

The SPST relay switches the coil on and off.

That's all there is to it.


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