Think of it in terms of poor throttle response : As the engine slows a
little, the governor opens the throttle a little, but the engine doesn't
respond immediately, so the governor opens the throttle some more ...
until finally the engine responds, but now the throttle is open too far,
the engine overspeeds, the governor closes the throttle, ... and the
I'd start by looking for the fuel mixture to be slightly lean (is your
gas fresh ? 2-cycle mix seems to go stale much quicker than unmixed
gas.), then for ignition problems (try a new plug).
Mike Frerichs wrote:
> Anybody know anything about small engines? (I know, silly question to
> ask on this list!) Specifically, a two year old Lawnboy 2-stroke (it's
> always had the proper gas/oil mixture). Last fall it was starting to
> run a little badly and the engine speed was starting to fluctuate. I
> figured I'd wait till spring and clean the carb and that would be that.
> Well, Saturday I took the carb all apart and cleaned it inside and out
> (mostly out, because the inside was very clean already). The main
> (only) jet was not clogged at all. I put it all back together and
> cleaned and oiled the air filter. When I started it up it seemed to run
> perfectly (no missing or coughing) but the speed continuously goes up
> and down.