On Sat, 21 Aug 2010 19:08:40 -0500, The Daring Dufas wrote:

All reciprocating (piston) engines are basically air pumps.

Ah. Now I understand what you're saying. Thanks for the details.

I tried blowing about 50psi compressed air into the spark plug hole ...
with mixed results (my compressor doesn't go higher than that).

- If the piston was at the top, it fluttered (see details below).
- If the piston was at another spot, it blew out the exhaust.
- If the piston was at yet another spot, it blew out the carbeurator.

But it never did run the thing (I think because of the pull-cord clutch
mechanism because it 'looked' like it wanted to spin but couldn't spin.
Probably because it wasn't fast enough to make the pull-cord clutch
disengage.

So, I think the "fluttering" was the piston trying to turn the crankshaft
but it couldn't because of the pull cord. I guess I could remove the pull
cord and test it without the pull-cord clutch...