Slightly O/T.. Lawnmower problem

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
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Maybe the spark plug needs replacing.
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"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
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Scott Bowers wrote:

This is the point I give up, and send it in.
Unless its a simple broken plug lead?

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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.
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Andrew Gabriel

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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
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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

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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
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