Subject: CC Magneto
From: Rotary Engine
Date: 4/14/2009, 6:13 PM
To: AAA Put this in the To box



Bill Jepson has sent TWO messages that are relevant to using this unit
as a basis for a Cheap Chinese (CC) Magneto.  (Note the new thread
name.)

----------------------------
Paul,

I think it's funny I haven't seen that mag since 1976! As a young (very)
mechanic that exact same looking mag was used on the Kawasaki G31M.
Kawasaki's
first effort into a 125cc motorcross bike. The early ones had a points
cam on
top of the permanent magnet rotor. The funny part was if you revved
the motor
past 1500RPM you could hold the points open and the magnetic pulse
would still
fire the plug. Sounds like it's right up your street for things that
need
little to keep running. The later ones used a tiny box and a hall
effect pickup
to trigger. A true magneto though as the bikes had no battery at all.

Bill Jepson
----------------------------
Paul,

Unless I miss my guess I believe you will still need to have
an external high tension coil.  That unit is the crankshaft attached
unit for a SINGLE cylinder Honda copy laydown 50 or 90cc engine. The
little box is attached to the small trigger coil at about 3:00o'clock
in the picture, and it is a points replacement.

Bill Jepson
----------------------------

Since the unit has been around for 30+ years, I feel better about its
reliability.  For firing plugs in a two-rotor engine we could graft
two units together 180 degrees apart around a single magnet rotor.

I'd still think about building/buying a high-quality igniter, though,
unless we test the included igniter for hundreds of hours.

Triggering still needs further examination.  I am guessing that the
trigger fires 3 times per revolution (3 magnets = three cycles/pulses).

I probably mistranslated the Chinglish phrase "high pressure bag end"
to mean "high voltage spark plug".  It most likely means "high voltage
ignition coil".

Again, I have included a picture of the $45 unit.  Also included below
is Paul's schematic from a Mariner CDI system.  On the schematic,
ignore the bottom "Lighting Coil" portion.

For slow speed cranking issues, we could parallel power the igniter
input with the battery (through a diode or bridge rectifier).  This
would ensure that the igniter has plenty of power even when magneto
juice is feeble.

Of course the (induced) trigger signal needs to be adequate to fire
the igniter's SCR.

I'm feeling better about this as a pursuit for a rotary engine magneto
option.  It's something that the conservative Lycoming crowd will
understand and respect, as opposed to the ECU ignition that most
rotards are using.  :)

-Vince Orton



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