Several things could be the issue.

* Sometimes the gasket between the carb and the engine body
dries out. Or people neglect to replace it. Pull the carb,
and make sure it has a gasket. A very little bit of Permatex
#2B Non Hardening gasket sealer will be a big help. If the
gasket isn't there, put a little permatex on the carb to
engine matching surfaces.
* Only buy new gasoline, of a trusted name brand. Pay the
couple extra cents and get good brand. In the western NY
area, Mobil and Hess are good.
* If the spark plug is Champion, try a different brand. They
had bad sparkplugs in the past.
* Like the guys say, try a squirt of ether on the air
cleaner filter before starting. If that helps, you likely
have fuel supply problems.
* A trace of water in the fuel tank will cause this kind of
problem.
* If the gap between the flywheel and the ignition coil is
too great, the spark will be weak. Normal air gap is about
the thickness of the cardboard they use for spark plug
boxes.

Please let us know how things work out. If you get it going,
or not. Either way, please write again. That way, we can
learn also.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"muzician21" wrote in message
...
Have a B&S on a 70's era Snapper 21" pusher with an aluminum
deck. I
believe the engine is probably 10 years newer than the rest
of the
mower.

Maybe 10 years ago I took it to a repair shop who installed
a solid
state unit to replace the points. Even with the solid state
ignition
it was never one-pull start, but as I recall it usually
started with
probably 3 - 5 pulls. Now it takes probably 20 pulls or more
and
monkeying with the throttle. Once it fires it runs like a
clock, runs
up and down the speed range fine. It's also easier to
re-start once
it's been running - though still not one pull. Doesn't seem
to use an
inordinate amount of oil, no discernible smoke out the
exhaust. It
gets what I'd call moderate use. I'm in central Florida so
it gets run
bi-weekly or so during the rainy months, not at all during
the months
of what passes for a winter down here.

I'm mechanically inclined but not well-versed on the theory
of this
kind of engine. I've had it broken down far enough to remove
and flush
the gas tank, change the points when it had points, replace
the pull
rope. I've change the spark plug of course. I know it should
start
much easier than it does. Any suggestions where to look,
what to
tweak? There isn't that much to it from what I can see, so
it
shouldn't be that difficult. I believe this mower has a lot
of life
left in it.

Thanks for all input.