bof wrote:

In message , Nick
writes

I have a Mountfield lawnmower with a Honda GCV135 engine. I tried to
use it
the other day and although it started immediately it wouldn't run at a
constant speed. It slowed to a stutter and then speeded up then
slowed down
and so on.


Mine (with a Briggs a Stratton) will do this after it's been running a
couple of minutes, if the fuel tank has been filled right up; if I
unscrew the petrol cap it's all OK again, so I guess it's due to a
vacuum in the tank.


Supposed to be a pinhole in it..