no spark

[bertsmobile1]

If the flywheel key is broken, the flywheel probably won't even turn and the shaft will just spin inside the flywheel. Clean the magnet surface and coil surface and stick a piece of paper between the two, about ..002" gap and usually that works for me. Make sure to blow off any steel wool or dirt. They need cleaned often if left in a cold barn over winter. I always try the easiest fix, which is a new plug.

Absolute rubbish
Magnets do not need to be clean and neither do the laminations on the coil.
I strongly suggest you go back & read your science text books from high school
Next the air gap is 0.010" not 0.002"
On a Hall Effect trigger which is what is inside the coil, the closer the coil is to the magnet the EARLIER the coil will fire
Thus you are advancing the timing by reducing the air gap.
You are also making the spark weaker because the coil fires before it reaches maximum voltage .
Neither the coil nor the magnets need to be clean the only important thing is they do not touch.

Next, the key s a timing key not a power transmission key and the engine will run just fine without one all together
It is just there to keep to fluwheel in alighment with the crankshaft while you are tightening the nut down onto the taper which is what transfers rotation form the starter to the flywheel

 

[StarTech]

If the flywheel key is broken, the flywheel probably won't even turn and the shaft will just spin inside the flywheel. Clean the magnet surface and coil surface and stick a piece of paper between the two, about ..002" gap and usually that works for me. Make sure to blow off any steel wool or dirt. They need cleaned often if left in a cold barn over winter. I always try the easiest fix, which is a new plug.

First the flywheel key is used for alignment only. It is the fiction fit of the taper shaft along with the proper compression torque that prevents the flywheel slipping on the shaft. Even at the proper torque compression of this tapered fit it can slip when excessive spin torque is applied. This is actual good as it prevents the flywheel from shearing off the crankshaft during a sudden stop. Plus most times when the key does shears it actually bind the jointing of the flywheel and crankshaft. Under torquing the flywheel retainer leads to shearing of this and over torquing can lead to flywheel damage.

Second setting the coil gap at .002 does throws the ignition timing off (advances it). The spec is usually .008-.012 with .010 being the desired setting. This why a standard business card is use most times to set this air gap. Note not all coil air gaps can be set this why as some OEM do have different settings.

Edit: and Bert is right that normally these don't need cleaning; although, coil to cylinder mounting might need cleaning depending if the coil is moved. Cleaning of flywheel magnets can actually demagnetize them if the wroung cleaning method is used such a spinning steel wire brush.

 

[Scrubcadet10]

If the flywheel key is broken, the flywheel probably won't even turn and the shaft will just spin inside the flywheel. Clean the magnet surface and coil surface and stick a piece of paper between the two, about ..002" gap and usually that works for me. Make sure to blow off any steel wool or dirt. They need cleaned often if left in a cold barn over winter. I always try the easiest fix, which is a new plug.

Wrong, the flywheel nut has a clamp load holding the flywheel to the crank against a taper, however it can rotate out of alignment, the shaft won't spin around inside the flywheel.
usually a coil gap around .008" to .012"

 

[VRR.DYNDNS>BIZ]

If the flywheel key is broken, the flywheel probably won't even turn and the shaft will just spin inside the flywheel. Clean the magnet surface and coil surface and stick a piece of paper between the two, about ..002" gap and usually that works for me. Make sure to blow off any steel wool or dirt. They need cleaned often if left in a cold barn over winter. I always try the easiest fix, which is a new plug.

This advise must be corrected. Without motor specs in front of me, no engine in over 50 years of service should be set at .002 air gap for the ignition coil. Also, the only advantage of cleaning the surfaces is to get an accurate setting of the air gap to.010 - .012. Dirt, debris, rust do not impact the function of the ignition coil. If set as tight as .002" then the flywheel and coil will rub and cause damage most likely. Also the torque on the flywheel nut if normal will keep the flywheel from easily repositioning itself on the crank shaft. It will migrate off setting under certain happenings on centrifugal aberrations, but most times it simply half shears the key and stays as sheared in a stuck position off time. Yes always try the plug first!! One more thing, it takes 300-400 rpm when spun to induce voltage levels sufficient to create a spark. Pull the plug when testing to insure sufficient spark energy with plug out, if spark found then compare with plug in except see my prior note regarding the metal shield on plug connector.

 

[VRR.DYNDNS>BIZ]

First the flywheel key is used for alignment only. It is the fiction fit of the taper shaft along with the proper compression torque that prevents the flywheel slipping on the shaft. Even at the proper torque compression of this tapered fit it can slip when excessive spin torque is applied. This is actual good as it prevents the flywheel from shearing off the crankshaft during a sudden stop. Plus most times when the key does shears it actually bind the jointing of the flywheel and crankshaft. Under torquing the flywheel retainer leads to shearing of this and over torquing can lead to flywheel damage.

Second setting the coil gap at .002 does throws the ignition timing off (advances it). The spec is usually .008-.012 with .010 being the desired setting. This why a standard business card is use most times to set this air gap. Note not all coil air gaps can be set this why as some OEM do have different settings.

Edit: and Bert is right that normally these don't need cleaning; although, coil to cylinder mounting might need cleaning depending if the coil is moved. Cleaning of flywheel magnets can actually demagnetize them if the wroung cleaning method is used such a spinning steel wire brush.

good advise - i duplicated cause I missed this advice.

 

[phoenix02]

I have a 4.75 hp Briggs cheap mower and no spark. Model 09T802 Type 10754 B1. I've tried everything and am looking at the flywheel magnets as well. My flywheel has three magnets. The large center one is quite strong and could hold up the largest screwdriver. The small ones can just hold up a 10 inch flathead screwdriver oriented parallel to the crankshaft. It's a disposable mower but it's barely got any hours on it. I can get a Neodymium magnet for $10 and determine the polarity of these two outboard magnets to rub the Neo magnet axially and hope it energizes them. Any other ideas that won't cost more than the mower is worth?

 

[VRR.DYNDNS>BIZ]

model and type please if you want help. Also, I do not believe any had tree magnets, only 1 or 2 on the very old machins with points, other wise one. Ther are counter weights that may look like magnets and may have taken on some magnetism, but not part of spark system.

 

[phoenix02]

model and type please if you want help. Also, I do not believe any had tree magnets, only 1 or 2 on the very old machins with points, other wise one. Ther are counter weights that may look like magnets and may have taken on some magnetism, but not part of spark system.

Edited original post with model, type and pic of magnets. If the side irons are counter weights, they are magnetized. Maybe that is the problem. Do I need to purge the magnetism from those side irons?

 

[StarTech]

Fat finger model.

09T802 Type 10754 B1 >> 09T802-1075-B1

Have you tried a new coil?

https://www.ebay.com/itm/394212215758?chn=ps&_trkparms=ispr%3D1&amdata=enc%3A1PjQm2ckiQP2oeCnNK5gYfQ40&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=394212215758&targetid=&device=c&mktype=pla&googleloc=9013259&poi=&campaignid=17597089569&mkgroupid=&rlsatarget=&abcId=9300988&merchantid=6296724&gclid=EAIaIQobChMInard1onu-gIVks6GCh2e4wwtEAQYAyABEgKmYfD_BwE

Also be careful messing with the flywheel mags as that flywheel is NLA.