On Thu, 30 Mar 2006 12:59:21 GMT, Nick Hull
wrote:

I tried alt.electronics.repair and didn't gat any good ideas. I don't
expect you geniuses to solve my problem but maybe someone can point me
in the right direction. The 3-wheeler only cost $400 when I bought it
used many years ago!

Between the flywheel pickup coil (magneto) and the high voltage coil for
the spark plug there is a black box that controls the spark and its
advance. This box on My Kawasaki 3-wheeler is called the Igniter and
this simple tiny circuit board costs $400! It was designed before 1982
and contains one IC and a bunch of discrete components. There has got
to be a better (cheaper) way to do this.

The spark starts at 10 deg before Top Dead Center and advances to 40 deg
before TDC by 2000 rpm. Since electronics cannot advance time
apparently the pickup is at 40 deg BTDC and the pulse is delayed to 10
deg BTDC at low speeds. If the timing delay fails the spark reverts to
40 deg BTDC for all speeds, meaning the engine cannot run at low speeds
therefore cannot be started. Bad idea.

How could this black box be designed using components availiable today
to control the spark advance, preferably adjustable or programable so it
would work in a wide variety of ATVs etc? If possible It would be
preferable to have the failure mode at low speed advance. Certainly I
would hope for a price below $400. All suggestions welcome

Some of the first solid state ignitions for garden tractors used two
pins to trigger the coil. The one for TDC was taller and swung closer
to the trigger coil. The advanced timing was shorter and wouldn't
trigger the coil at lower rpms. As the rpm came up the advanced timing
would kick in. Chrysler solid boxes have been substituted on some of
them.

http://sears.panmar.net/ssi.pdf
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