The problem appears to be no spark ,( proven with neon-timing light)

I had a problem similar to this several years ago where the lawnmower
sometimes ran erratically and then finally falied to start. I proved
that it was due to no spark by taking out the spark plug, resting it on the
metal engine and looking for a spark when the starting cord was pulled..

I eventually traced the fault to the switch that controls the switching off of
the engine . This is connected via cable to the operating lever on the
handlebars that you have to hold ON when you are using the mower.( When
released , it earths the spark plug lead via this switch preventing firing at
the sparkplug and also applies a mechanical brake to the flywheel)

It was fairly easy to prove using a multimeter and if I remember correctly , it
was due to a sticking plunger that operated the microswitch. I cured it by
cleaning it up and lubricating it with a small squirt of WD40.

It`s ran OK ever since.

If that`s not the problem , then I would suspect the magneto , but magnetos are
usually very reliable.


If you want any further info then email me and I`ll see if I can help as I`m
still using the mower.

Vic