What sort of cement did you use?

You will be better off replacing the flywheel. Even if you felt you could successfully re-attach the magnets with glue or epoxy, the individual magnets have a specific "polarity" and are placed in a specific manner when the flywheel is built by the OEM. You would be unable to duplicate this and so your "repaired" flywheel might not even function as intended. You could take your defective flywheel to some small engine shops to match it up with a used flywheel. Every time an engine suffers a catestrophic failure, a "used flywheel" is produced. Some shops hang onto parts like that and you might get one cheap. Be aware of the composition of the ring gear teeth of a used flywheel, you want it to be the same material as the original ring gear, or you can swap the ring gear you just bought, if the ring gear of the used flywheel is different.

Awwww..thank you mownie for the swift reply but that's not what I wanted to hear! I guess i'll just have to bite the bullet and get another flywheel.

I have successfully re-glued those magnets, using JB WELD, an epoxy adhesive. Seem to work, as long as the magnets aren't broken. Don't ever recall anything about polarity, but then again, i'm just a fixer!

Well magnets certainly can be reattached as Rusty says and a simple check of the polarity of 4 or so adjacent magnets will show what sequence needs to be used to reattach them plus outline of positioning will be evident in the flywheel.

Clamp them over night.

Walt Conner

ATTENTION! Once again............it's time for me to eat crow.
I really hate (honestly) that I stated "the individual magnets have a specific "polarity" and are placed in a specific manner"
That statement DOES NOT apply in the case of this kind of electric generator. I did some research through my library of old tech stuff and electrical theory books (online too) and came to the opposite conclusion than what I stated earlier. The reason why the polarity of each magnet makes no difference in this application is due to the output current being rectified by a diode (or diodes plural in some cases). When a magnet passes by a coil of wire, the flux field of the magnet induces a current into the coil. The direction in which the induced current flows out of the coil of wire, depends on the orientation of the poles (commonly called North & South) of the magnet. Because the diode only allows current to pass through it in one direction, it makes no difference to the diode, or the alternator coil, which magnetic pole passes the coil first, the current produced by the individual coil & magnet will still be recified into DC which the battery needs.
IF.....the output current was being rectified by a COMMUTATOR instead of a diode, the polarity of the magnets would be crucial.
My impulsive (and erroneous) statement about the need for polarity matching was based on the use of permanent magnets used in DC powered motors, such as those found in modern small engine starters and other automotive applications.
The permanent magnets used in these small DC powered MOTORS must be arranged with a specific polarity pattern or the motor simply will not work. The reason is because the rotor (armature) of the motor recieves its current through a COMMUTATOR (click link). Because the bars of the commutator are passing current into a series of overlapping coils which produce a strong electromagnetic field when energized, the poles of this electromagnetic field will be attracted to the opposite poles (North to South is attractive) on the permanet magnet field surrounding the armature. But, the poles of this electromagnetic field will be repulsed by their identical poles (North to North is repulsive) on the permanet magnet field surrounding the armature. Unless each permanent magnet comprising the field of a DC motor has its poles aligned in the same direction, the electromagnetic field of the armature will be in conflict with the permanent magnet field, and the resultant "push-pull" of the changing impulses will kill the rotation, and then you don't have a motor.
Having gone and done some refreshing research on this makes me wonder now if Briggs even bothers to match polarity when a flywheel is assembled. ??
funflyer, I sincerely apologize to you and all readers (but especially to you because it's your dime and time) for the initial bit of "misinformation" that I dispensed.
And I applaud Walt and Rustyj for posting contrary reports. If you guys had not gotten me to wondering about it, I might have gone on believing my unrealistic explanation that I first gave. I'm very sorry about this.
I hope everybody has a safe and happy Thanksgiving. I guess you know what bird I'll be eating.

{{gwi:338856}}

Here is a link that might be useful: Just a bit of theory

Mownie: Are you the guy in the picture--the one with the cape?? Yuk, yuk, yuk!

I'm the dumbest looking one, and as you can see from the scowl, crow ain't one of my favorites, but, if you do the crime...you do the time!

I recognize Kenny Rogers, mownie, but which of the other ones is you‽

Mowie, while you have written an impressive book, some of which actually applies to the question at hand, I question that portion.

Walt Conner

In short folks, when re-attaching magnets in B&S flywheel, orientate them the same way as the other magnets.

Walt Conner

Yea did that same thing with a Kohler Command that dropped out about 7-8 of the magnets. I just re glued them in with, you won't believe this, Liquid Nail caulking paneling glue. Hey I didn't want to have to wait and go after some epoxy glue,and it worked, so I never told my customer that it happened and how I fixed it. I haven't heard from him about his Kohler failing to start, and that was early this past April, so I'm guessing its still hanging in there.

***"Mowie, while you have written an impressive book, some of which actually applies to the question at hand, I question that portion."***
OK, It is "an alternator" by the modern definition of alternator. That means the alternating current (which is caused by the alternating North & South poles passing the coil) is presented to a diode to be rectified electronically by a semi-conductor, instead of being rectified physically/mechanically by a rotating commutator.
And keep in mind, I am talking about an alternator that uses permanent magnets to create the rotating field. Also, keep in mind that these alternators actually swap the roles of the same compontents (rotating member= rotor, stationary member= stator). In a "DC generator", the current created is AC, but the useful OUTPUT power produced in the rotor (aka armature), is rectified by the commutator at the same time it is delivered to the machine's electrical system via a set of brushes that contact the commutator. The field is stationary in a DC generator, and varying the voltage fed to the field, will vary the voltage output of armature.
Because the commutator is a physical and mechanical, "rotating contactor", the polarity of the current being created in each individual coil of the armature (and their are several) must be absoutely identical to the polarity being created in the other coils, otherwise, you would be feeding a pulse of "opposite polarity" into the battery whenever that coil's commutator bars came into contact with the brushes. This opposite polarity pulse would have the effect of "discharging" the battery each time it offered its current to the mix.
But I don't know of ANY DC generators ever employing "permanent magnets" as the sole exciting source of field current. Yes, all the DC generators did/do have and use, residual magnetism in the field shoes as a result of the electromagnetic processes that take place during operation. But, that residual magnetism came to be used as a means of ensuring that the generator could begin making electricity by itself (with no external current applied to the field), even if the machine's battery was "stone dead". But, if there was an application that used PERMANENT MAGNETS as the "sole" exciting field for a DC generator, ALL magnets in the field would have to be arranged in identical polarity or the output would have some pulses of opposite polarity, which would have the same effect on a battery as if you fed alternating current to the battery, and a battery can not utilize AC because a battery is strictly a DC based component. AC fed to a battery results in a "null charge condition" because for every pulse of current in the correct direction that could add a bit of charge to the battery, there is also a pulse of current in the wrong direction that subtracts a bit of charge from the battery.
OK, let's jump to an alternator that uses several permanent magnets in a rotating field (flywheel in this case) and several coils of wire in a stationary output component. This hypthetical example alternator is a "single phase" version (meaning it has only one output conductor offering power to be rectified). Keep in mind here that electricity travels at about the same speed as light (commonly referred to as 186,000 miles per SECOND), while the flywheel turning 3,000 RPM, is hardly even creeping in comparison. As each permanent magnet in the flywheel rotates past one of the coils in the stator, a current is induced in the coil. Because the magnet has a North pole & a South pole, the induced current will change its direction of flow, from "North to South", or, from "South to North", depending on the physical orientation of magnet's North & South poles as it passes the coil. The output current of each coil tries to travel out of the coil, through the other coils (they are all in series on this circuit), and into the electrical system of the machine, THROUGH THE BATTERY, and out to ground where this pulse will re-enter the coil wiring at the other end of the coil (stator wiring has 2 ends, one end is "output", the other end is connected to the engine and chassis ground, if you do not provide a complete path, you get no flow of current).
OK, it does not matter which direction the induced current is flowing through the coil when the induction begins (magnet is approching the coil), nor which way the induced current is flowing when the induction ends (magnet is departing the coil) because the rectfying diode is only going to allow the half of the total power pulse that has the correct polarity, to pass through and travel the complete circuit through the battery and finally back the stator through "the back door". When multiple magnets are used with a single circuit stator, either the magnets, or the individual coils must be "staggered" or, unevenly spaced along the circular layout alternator to prevent any "butting of heads" of power pulses that might be caused by two magnets having opposite polarity. And because all of the electrical induction and power output pulses occur at light speed, an individual coil waiting for the next passing magnet, could be likened to someone waiting at a bus stop, for a bus that only comes by twice a day. So, it does not matter about the polarity of each magnet in this application, the diode decides which half of each pulse it will permit to go to the battery, whether that correct half shows up at the gate first......or last.

As I have said before, I tend not to read very long posts including this one. Check the pattern of the existing magnets, they are that way for a reason, perhaps more research.

Walt Conner

That is acceptable.

I will say this, I suspect you are thinking single coil, perhaps multiple magnets theory. We have multiple coils connected in series, multiple magnets which must cause each coil to change direction of flow at the same time AND in the same direction. Think about that.

Walt Conner

WOW!! That explanation boggles my mind! I was never one to try to figger out elctrical problems, other than pushing the reset button, screwing in a new fuse, or calling an electrician friend to come and fix the problem.
Had one---Main fuse box blew out on New Years eve, one year! All ready to go to visit relatives across town. Temp at 10D. No way to heat house! Called guy next door, he got a new breaker box on N.Y.D., installed it then, and we got out of that fix. Must of been right--that was 20 years ago, and had it checked by an electrician. Been Good!

I'd just look on Ebay for a used one going cheap. Did I say cheap? yep, that's me.

You can reglue these magnets inplace , Use Loctite glue #331 and activator # 7387, This is an industrial glue used for installing magnets. Make sure all surfaces are real clean apply glue to one surface and activator to the other make sre gaps between magnets are correct and press together, bond is almost instantanious so be very careful. Hope this will help you and any others with this problem.