Briggs and Stratton powered rotovator. No spark. I recently moved to rural France whhere abandoned at the back

Question

I recently moved to rural France where abandoned at the back of the barn was a Briggs and Stratton single cylinder petrol rotavator.
I have been on the web but of course on the B/S site you have to live in the US to get an answer.

There is no spark.
I have had the plug out. Gap by eye seems ok.

No sign of a spark at all.

Took off dust cover. Removed Coil which is wrapped around a laminated core.

This device is what I believe the Americans call a Magnetron.
Cleaned up everything. There is a magnet embedded in the flywheel. Still seems quite powerful.

There are three wires coming from the coil plus the HT lead. Two of them are twisted and soldered together and end in an earth lug.
The other which I believe is the stop wire broke off close to the coil. Its too close to risk trying to re-attach.
The stop switch is not mounted directly on the Magnetron but on a plate near the end of the Throttle/ stop cable.

The wire from this disappears into the crankcase

I

Yes..the stop wire disappears into the crankcase and seems to reappear out the same hole on its way to the cut off switch.
I have not had the flywheel off yet but am I right in thinking there are no points in there anyway?

I have measured the resistance from the stop wire to the other two (earths) This is very low less than a few ohms (I am not there at the moment so cant give an exact number.) the resistance from the HT lead to any of the coil wires is consistantly 2850 ohms. Is this ok?
Do I need to replace the Magenetron. I have by eye set the gap between it and the flywheel.
If I replace it is it the end of my problems?
Any help gratefully recieved but please dont answer if you dont know what you are talking about.
Thanks in advance.

Answer 1

The cable that disappears into the crankcase goes to the points and condenser.

You need to remove the flywheel and behind it you will find a set of points that are operated by a small pushrod that runs on a crankshaft driven cam.

All the bets are on the pushrod being stuck in the housing and the points are stuck open hence no spark.

Answer 2

Depending on the age, there could be points. I have a mid 70's briggs with points. The plunger that moves the points was/is stuck in the hole. I installed a newer coil module that does not need points and it works great. Get the engine model numbers off the cowling and go to outdoordistributors.com. Under briggs and stratton type in the engine numbers. This should get you an exploded view of the engine and a parts list. This will tell you if you have points or not. No need to remove the flywheel to find out. The new coil module is about $60 US.

Answer 3

try removing the flywheel and then clean (with fine sandpaper) both the contact point on the inside of the flywheel and the coil ?? segments that contact the inner magnetised segment on the inside of the flywheel.
These parts sometimes rust up due to not being used.
Before re-assembling the starter cover back onto the machine try putting a 3/4"? socket onto the protruding starter spindle then attaching it to a portable drill which will save you pulling the "pull cord" each time
Amazon do a "Briggs and Stratton" workshop manual which I found very useful when repairing lawn mowers.
Hope this helps you
Blacklabrador-Birmingham-UK

Answer 4

frequently the spark plug hollow would be .030”, yet this would rely on the form and form variety of the engine. you are able to double examine the hollow specs in the engines vendors instruction manual. you are able to discover the instruction manual on the Briggs & Stratton internet site on the link under.

Answer 5

i would like a pound for every dead plug i have had that looks allright ..try changing the h.t lead ..i allways check for a spark by puting a finger in the plug lead and giving it a pull..most times the problem is the cutout switch .dont give up

Answer 6

looking down onto the top of the flywheel there is the crank shaft. where the fly wheel slides onto the shaft there is notch where a woodrif key is used for proper alignment if it is sheered it is "out of time" and will not fire.