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[email protected] etpm@whidbey.com is offline
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Default Briggs and Stratton 3.5 hp lawnmower engine problem

On Sat, 26 May 2018 14:06:36 -0700 (PDT), John-Del
wrote:

On Saturday, May 26, 2018 at 1:52:31 PM UTC-4, wrote:
On Sat, 26 May 2018 10:38:17 -0700 (PDT), John-Del
wrote:

On Saturday, May 26, 2018 at 12:51:13 PM UTC-4, wrote:
On Fri, 25 May 2018 18:28:53 -0700 (PDT), wrote:

On Saturday, 26 May 2018 02:06:45 UTC+1, wrote:

There were a lot of Briggs and Stratton electronic type magnetos that
were prone to failure. I use a method to test suspect magnetos before
I spend much time trying to find out why there is no spark. Remove the
spark plug from the engine so that it turns over easily. Then stuff a
rod or something similar into the the spark plug boot so that it makes
good contact with the end of the spark plug wire. Now turn the engine
over slowly while holding the rod. You should get at least a tingle.
If no tingle then try turning the engine over a little faster. If
there is a little tingle then the problem is most likely a bad
connection. This could be a corroded ground wire. If, even turning
the engine over fairly fast, there isn't even a tingle the magneto is
bad or the kill wire is grounded. I have used this method for years
and it is a really fast way to find out if the mag is probably good or
not.
Eric

say hi to Darwin for me.
Oh phooey. There is no way you can get a dangerous shock from slowly
turning over an old lawnmower engine equipped with a magneto. Sheeesh!
Eric

Exactly, on a small magneto like this it'll tickle, but this reminds me of a true story:

Many many years ago, a guy I knew was having some ignition work done on his stock Hemi Challenger at my buddy's garage, and brought along a magneto to try just in case. Just rotating it a half turn sent him flying! Those things have balls.

Was the mag the type that winds up when being turned over slowly? I
have some old magnetos that work this way. One is on my 1945 Gibson
tractor. When turned slowly it winds up a spring inside that lets go
when it reaches a certain tension, thereby spinning the magnet fast
enough to get a good spark. Those mags will deliver a really good
shock. Years ago I had one of these that would only deliver a little
tingle. Talking to a guy who knew about mags said that the coil may
have absorbed moisture over time, especially since the mag was from a
marine engine. He suggested baking the mag in oven at 200 degrees for
several hours and then letting it cool in the oven. I tried his
suggestion but was dubious. After it was cool I grabbed the spark plug
wire and turned the mag over. When it let go I got a really good
shock. Made my arm ache.
Eric


No, just the type they used in race engines. Something like this:

http://www.westracingproducts.com/MS...-V8_p_981.html

They must have some pretty strong magnets and the voltage at operating
RPM must be VERY high. I guess that's what is needed for really high
compression engines.
Eric