Do these things fail all at once or gradually? All relevant surfaces were buffed clean, tried different plug, tried different (used) coil. flywheel key is OK.
Chipper was unused for3 yrs +/-
Most often they just break down, but they can go gradually. How about supplying us with the model and serial numbers from the engines. COVID has killed our psychic powers and we have no idea of which engine you are talking about.
#3
Hammermechanicman
"Weak spark" ?
Remove spark plug and use a gap style tester OR put a bolt in spark plug lead and position it 1/4" from engine block and spin engine over. Does the spark jump the 1/4" gap? If yes coil good if no coil is bad.
On those older engines I have found that armature air gap is critical. Try setting the gap to .008”. Second I’m assuming that you have not installed the coil upside down?
Do these things fail all at once or gradually? All relevant surfaces were buffed clean, tried different plug, tried different (used) coil. flywheel key is OK.
Chipper was unused for3 yrs +/-
When you say Flywheel key is ok , did you actually remove the flywheel and look ? This is the last mistake I made on a Techumseh , It looked good from the top, new plug, new coil, lots of sanding and cleaning to end up with a sheared key.
Weak spark is not the problem. If a visible spark, no matter the appearance , you have spark. The appearance is merely an effect of the air in vicinity of the spark. the killovolts necessary to jump the gap are either enough to jump the gap or not enough and no spark.
#10
Hammermechanicman
I really can't believe how folks over complicate checking for spark. Remove the spark plug and use a gap type tester or stick a bolt in the plug wire and position it with a 1/4" or 6mm from engine ground and crank engine. If the spark jumps the gap the coil has enough energy to run the engine. Color of the ionized air is not important.
The strength of a magneto spark is directly proportional to the speed that the magnets pass the coils.
Ask any one who rides magneto powered motorcycles about this
So what looks like a pathetic weak spark at cranking speeds can be a blow you away spark at running speeds .
That is why B & S make the 3 point spark tester ( magneto strength tester ) and the sliding contact magneto strength tester was invented.
I have one. Don't really use it much. I think that is the vid that starts out with a small gap and then opens it up to 6mm with it running. I just grab my briggs tester. If it will jump the gap it will run the engine. Some folk say they can analyze the condition of a spark plug with an adjustable gap tester. For $2 i just put in a plug and leave the VooDoo plug analysis to others. There are as many myths and "internet facts" about spark plugs as there is about motor oil.
