allis b110 melting wire off of coil

dmiller

Member
I have a student at school who is trying to figure out why his B110 keeps melting the black wire (not spark plug wire) off of the coil. Briggs 24000 series engine.

I don't think all of the wiring is there and I'm having troubles figuring it out. There is a wire from the condenser, one from the coil (another from coil that obviously goes to ground), and one from the insulated post coming out of the points cover.

If I'm correct the wire from the coil, connects to the wire on the insulated post of the cover, the one from the condenser also goes to the insulated cap.

Thanks,
 
That would be correct. He could try one of the Megafire or Nova 2 electric triggers and bypass the points/condenser. They are about $15 on eBay. Really not sure how the wire could be melting.
AaronSEIA
 
That engine would have originally had magneto ignition, with the coil under the flywheel housing sheet metal. (Briggs calls it an "armature".)

If you can see a coil out in the open, likely someone has converted it to automotive style "Kettering" ignition that is battery-powered. Normally, a small condenser would be tucked in under the points cover, nothing external.

As to the wire burning off, if it HAS been changed to a battery-powered ignition system, primary current should only be about 3 Amps, which shouldn't be burning off any wires. Sounds like there make be a very small wire or poor connection.

Also, depending upon the primary resistance of the coil, a ballast/dropping resistor may be needed.

Coils intended for Kohler one-cylinder engines work well for these conversions, as they have the correct primary resistance, and don't need an external resistor.

Here's some links that may be helpful:

http://www.simpletractors.com/models/b_series/1968_cat/b-110_&_b-112.htm

https://www.google.com/url?sa=t&amp...df&usg=AFQjCNEl54Nyrg2IW5_AhDFthBrhGZz4rg

https://www.briggsandstratton.com/c...atton/na/en_us/Files/FAQs/270786-domestic.pdf
 
I run 10w-30 year round in mine. Book calls for 30. You can take all the model info from the engine shroud to the Briggs web site and download a free manual for the engine. I have a wiring diagram for the tractor that I can post tonight.
AaronSEIA
 
The wiring is very simple on a coil.
Hot wire from ignition switch to + side of coil.
Other side of coil has a wire to the points with a condenser connected to it.
Your are getting a lot of juice from somewhere to burn wires on the coil. LOL Bob
 
Here is the wiring diagram. Still not sure what coil you are talking about. If factory, then there is zero chance battery voltage is doing it. If not factory, I'd return it to factory. That'd probably fix it.
AaronSEIA
35280.jpg
 
Original in the flywheel coil can be bought for $25 or so. Throw a Megafire trigger on it and for under $50 it should be fixed.
AaronSEIA
 
Throttle cables runs along the top side of the engine and attaches to the thin rod that comes off the gov arm and runs through the top bracket. It has th 2 nuts on it to control max rpm. You'll see a hole in the middle of that rod. Throttle wire goes there. If I think of it, I'll snap a picture tomorrow of that. I think I have an engine wired factory with the on the flywheel coil. I'll get one of that as well so you can see how it hooks up.
AaronSEIA
 
I don't have an engine set up with the original armature coil setup. It is Briggs part # 298968 if you want to get one. I did snap a picture of where the throttle attaches. Sorry for it being sideways.
AaronSEIA
35546.jpg
 
If it's burning the wire off the coil, you have the wrong ignition switch. B&S uses a magneto. When you turn the switch to the run position, it's just open. When you turn it off, it shorts the ign terminal to ground. If you have a battery ign switch, it runs battery voltage to the coil. The Briggs coils don't like having battery voltage run to them.
 
Wire off the points, small wire to the mag, and wire to the key switch all tie together. Can you post a picture of what you have? Hate to come across as rude, but your questions have been answered several times and you keep asking them. We all want to help, but knowing what you have will make it easier. My email is [email protected] if you want to send some pictures.
AaronSEIA
 

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