On Tue, 25 Jan 2005 00:12:32 GMT, "Martin Whybrow"
wrote:

There's another reason; bike engines have timed ignition systems which
prevent the engine running backwards; most glow plug engines rely on the
induction timing to prevent reversal. The small reed induction engines (e.g
Cox 049) use a starter spring to ensure that they only start in the correct
direction (you hook it around the prop, wind it backwards a few turns and
let go), you couldn't easily do this with a larger engine. I know from
experience that if you try and start one of these reed induction engines
with your finger, they bounce off compression and start backwards; that's
led to a few very short flight on occasions ;-)
Martin

Two stroke bike engines will run backwards. Just ask someone who has
stalled an engine on a hill and rolled back a few feet and let the
clutch out to stop rolling.