On 8 Aug, 22:49, "Mark" wrote:
The Natural Philosopher wrote in ...
A.Lee wrote:

My spare lawnmower, a Mountfield, B+S engined SP470 is playing up.
It is revving and slowing, revving then slowing etc.

It is all related to the governor springs/fan, which slow it down when
it is revving too much.
Now this wouldnt be a problem if they work, and are easy to adjust, but
they rarely work properly, and are a pain to adjust - approx 10 mins for
each adjustment.
So I had an idea of doing away with the governor altogether and attching
a throttle cable to the linkage, to adjust engine speed that way. This
engine has no throttle adjustment, when under load, the governor is
meant to adjust it to give a constant RPM.

So , the query is - is it viable to do away with the governor and
control the engine speed manually?

Yes, but he main problem is that you will be constantly fiddling was it
runs into different loads.

It sounds like you have some friction in the governor..not just
maladjustmemnt.

Or it is running very weak (fuel mixture)

yes, much more likely.

NT