Advice: Remagnetizing flywheel magnets.

Evans, Marv · 10-04-2021, 01:46 PM

Thanks in advance. I have an old shredder bagger that I believe the flywheel magnets on the engine are weak. I've done a search for magneto repair to try to find out about remagnetizing the magnets. I got nothing, nada, zip. I'll spend a reasonable amount to get it done, otherwise the machine is gone - which I hate to do. Anybody have any sources, advice, comments. By the way, the magnets are internal on the flywheel.

Tishabet · 10-04-2021, 01:54 PM

My local small engine repair place has the equipment to do this, they did it for me a couple of years ago for my chainsaw. Might call around and ask.

Evans, Marv · 10-04-2021, 07:30 PM

Thanks Tishabet. I ended up taking the flywheel to a small engine repair to see if the magnets were OK. Turned our they were according to them. Why I can't get a spark out of this thing is a mystery.

Tishabet · 10-04-2021, 08:31 PM

Well, not many things that can go wrong on a magneto system... you sure your coil checks out? The gap between coil and flywheel is in spec?

Or my old favorite root cause: the kill switch itself. If your engine is equipped with one try disconnecting the lead from the kill switch entirely and see if you suddenly have spark.

GH85Carrera · GH85Carrera's Garage

My last lawn mower was 25 years old and simply worn out. The flywheel would wobble just enough to push the ignition module over enough that it would not start. I had to take the entire top of the mower apart, set the gap on the module to the flywheel, reassemble, and it would fire up on the first pull. I could not shut it off until I was done. Once shut off, it would not start until I went through the tear-down and adjustment 40 minutes of work. It was never going to get better, so it went to the curb and was replaced with a Honda mower. I miss the old Lawn Boy, as I think it was a better design and easier to use than the Honda, but I do like the first pull start of the Honda. The Lawn Boy was a first pull start for 20 years.

If the Honda lasts 25 years, it will last longer than I will be mowing so it is my last mower.

Evans, Marv · 10-05-2021, 08:25 AM

Grant. I've done all the stuff you mentioned but the coil/flywheel gap. It's an internal magneto, & I don't know any tricks for doing the gap. I'll try to figure something out. My wife wants me to trash it, but it's a great old machine if I can get it running.
Glen. I would think a wobbling flywheel would be pretty extreme. I have one of those 20+ year old, Honda first pull mowers too. I'm always amazed how easy it starts at the beginning of a season.

Zeke · 01:55 PM

Last time I had to fix a small engine I thought well after racing karts for 40 years (2-strokes) and building a 914 race engine as well as a few VW 1200's in their day, how hard can it be? So I throw parts at it like any dumb fkc would do only to find out it's s condenser.

A little sticker shock later it started right up. And this was a tired old edger motor.

I always did the gap with a business card. As long as it doesn't rub.

Tishabet · 10-05-2021, 01:58 PM

Quote:

Originally Posted by Evans, Marv

Grant. I've done all the stuff you mentioned but the coil/flywheel gap. It's an internal magneto, & I don't know any tricks for doing the gap. I'll try to figure something out. My wife wants me to trash it, but it's a great old machine if I can get it running.
Glen. I would think a wobbling flywheel would be pretty extreme. I have one of those 20+ year old, Honda first pull mowers too. I'm always amazed how easy it starts at the beginning of a season.

Here is how I set the gap between the coil (or magneto or whatever you want to call it) and the flywheel:
-install the flywheel including the key and tighten it down to spec
-loosen the screws holding the magneto in place
-rotate the flywheel until the magnet gets close to the magneto, the magneto should (if you loosened the screws enough) stick to the flywheel magnetically meaning you have zero air gap
-take something very thin (some like to use a business card, I prefer some plastic pieces taken out of the flat parts of a plastic 1 gallon milk container) and use as a shim between the flywheel and magneto at both of the "corners" of the magneto where it meets the flywheel. This will require pulling the magneto back from the magnetic pull of the flywheel, inserting your business card or plastic piece as a shim at the first corner, then letting the magnetic pull of the flywheel take over again. Repeat for second corner. Result should be a magneto that is "stuck" to the flywheel magnetically but is in fact gapped from the flywheel by the thickness of the business card or plastic piece of milk jug.
-tighten down the screws so magneto is again frozen in place, remove your homemade shims and voila... a magneto and flywheel which are air gapped.

GH85Carrera · GH85Carrera's Garage

When I gapped mine, I used a brass feeler gauge of the right thickness. The mower manual had the specifications for that gap.

Evans, Marv · 10-05-2021, 09:00 PM

Thanks Grant. I had a vague plan fermenting in my mind sort of like that, but you gave a great description. If the magneto was on the outside of the flywheel, it wouldn't be a problem. The guy I took it to was 71 & had been fixing things like this for years and didn't even come close to having a plan. I'll give it a shot.