It just uses a magneto type ignition (coil and flywheel magnets). Did you use a spark tester to check it? Many times just looking for a spark in the plug gap or the 'ol "screwdriver in the boot to ground" method will not show a spark when there really is one.
Look up the model on Sears Parts web site and you can see an "exploded" view it. http://www3.sears.com