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Collection, Preservation and Display of Old Lawn Mowers

Dead "contactless" magnetos

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I took the Briggs engine off the Toughcut mower this week, turned the engine over with plug out to check for a spark - nothing. I had noticed the cowl bolts were loose, so wasn't too surprised. Just in case it turns out to be a “heavy smoker”  I thought I would try it with a mag from another spare engine before buying a new one. Took the spare engine off the shelf and spun it over with the plug out, no spark. This mag is brand new, fitted last October, checked,  the engine run for a few seconds, and stored in a fairly dry place since. What is even more annoying, a neighbour asked me to “take a look” at his petrol hedge trimmer today, the mag is shot on that too. So, three dead mags in a row. Many of my old B & S engines with points have 30 to 50 year old mags that still work fine, after a points clean and re-set. Are these “contactless” mags prone to die if left unused for a while, or am I having a run of bad luck?
 

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wristpin Sat, 24/06/2017

In the case of the BS engine I'm assuming that by contactless you are talking Magnetron.  In my experience they are every bit as reliable as the old points and condenser set-up plus not suffering from periods of disuse. Be aware that with careful positioning the old system would spark with just a flick of the flywheel, whereas the Magnetron system requires around 350rpm.

 

 

merryman Tue, 27/06/2017

Thanks wristpin, the need for a higher speed was one of those things I had heard before but forgotten. I tried revolving the engines with an electric drill and they all started sparking. Tried some fuel down the inlet manifold, and the Toughcut's engine chugged away for a few seconds, don't want to put any fuel in the tank as it may stand for quite a while.

Now my diagnosis of the hedge trimmer having mag problems is shot, I will have to check the carb over. Throttle is a rotary valve, never come across that before.