Slightly O/T.. Lawnmower problem

[Scott Bowers]

I apologise for this question to be (slightly ?) off topic but I`m having a problem pull-starting my Mountfield Rotary Lawnmower .It has the Honda GV100 engine and according to the User Manual it has a transistorised Magneto system.

The problem appears to be no spark ,( proven with neon-timing light tester ) but I`ve not had chance to investigate further.( I intend to do this on Saturday in the daylight)

Has anyone any experience working on this type of Honda engine.

Any suggestions most welcome.

Scott

[Cold Ethyl]

Maybe the spark plug needs replacing.

[Scott Bowers]

"Cold Ethyl" > wrote

No, it`s not the spark plug unfortunately.(Already changed)

There`s no spark arriving on the spark plug lead ( proved by using a neon timing light tester )

Thanks anyway

Scott

[The Natural Philosopher]

This is the point I give up, and send it in.

Unless its a simple broken plug lead?

[Andrew Gabriel]

If it wasn't electronic, I would say it was the contact breaker or capacitor. I've no idea what replaces these in an electronic magneto, but it probably isn't repairable other than by a new electronic unit. Another possibility is moisture has got into the HV coil and the insulation broken down, but they are usually pretty well waterproofed.

[Smithtv]

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

[Rick Hughes]

I have an ISEKI mower with a Honda engine, I have had the electronic 'Ignitor' chip fail twice.

There is no spark at the plug when it happens - I know there are loads of other reasons that could be the cause, but as it has happened twice, maybe they are unreliable on Honda small hp motors

Rick

[Scott Bowers]

Thanks for all the suggestions , especially the last one.

The fault was due to the operating spring on the engine on/off switch being undertensioned.

This meant that the switch was never fully operated , even when the handle was pulled in the full on position.

I`ve taken it off and retensioned it and it now runs OK.

Thank goodness for that. I had visions of faulty electronics in the magneto circuit so it certainly doesn`t pay to jump to conclusions.

I bought this version of lawnmower mainly because of the well known reliability etc. of the Honda engine

Thanks everyone.

Scott