On 23/06/2020 06:53, Thomas Prufer wrote:
On Mon, 22 Jun 2020 20:38:17 +0100, T i m wrote:

The bottom line though is if it runs well enough to cut reasonable
length grass, that would suggest it was running reasonably well?

If it simply doesn't tickover smoothly but the revs hunt up and down
it could be running properly?

I have a Briggs&Stratton-powered cheap genset.

It hunts (vroom-vroom-vroom-vroom) when not electrically loaded, i.e. very
little mechanical load. Put a bit of load on it and it settles down.

OTOH, if you aren't sure you have attached the governor springs right: check
that. I tried to replace a missing spring with random springs selected from the
random spring box, and it didn't run anything like nearly right until I bought a
(surprisingly expensive) replacement part. Lever length, hardness, spring length
need to be spot-on, or very close. And there's usually a line of holes in which
the bits hook, get a wrong hole and you have just set it to "perfect for a
snowblower in the tropics" or whatever.


Thomas Prufer

spent 2 hrs trying to find out why my old revox turntable was
hunting...until I put the heavy platter back on, and it settled down
steady as a rock :-)

system theory and feedback stability mate. Too much negative feedback
and a little delay causes oscillations.

It's why the EU is hopeless. Too much administrative inertia to respond
to any changes. Not economic, not social, not medical...


You NEED localised feedback in any complex system with the minimum
amount of overall feedback.


--
Any fool can believe in principles - and most of them do!