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I just replace the engine in my Troy built. The old engine had a red wire with a black stripe c oming from the key and going to the gray wire that is hooked to the carburetor. It also had a plain red wire coming from the key and going to A another red wire that goes into what looks like a little computer bored. There are two yellow wires coming out of that that are yellow and go behind the starter 2 I'm guessing the alternator. The new engine which is used has a black wire coming from the armature where the spark plug wire start and the old engine didn't have that. It also has two wires, red and white coming from underneath the flywheel Which I'm guessing is the alternator. I'm not sure what goes to what because I don't have the diagrams for either engine. I already have everything else hooked up. Any help would be appreciated because wiring is not my specialty

If you keep screwing around with it, you will melt down your ignition coils at $50 a piece. There is no way in Hades that you will get good help here unless you let us know what you have.

First, post the model numbers of the tractor and the original engine, as well as the new engine, and tell us where it came from.

Pics are real helpful as well!

Thanks for the reply. Here are some pictures and numbers. The tractor is a Troy-Bilt with hydrostatic transmission and the model number is 13039/serial number 130390102037.

The old engine is a B&S 16hp, model# 303777 Type:0333-03/3898 Code: 94022811 and here are pics of the old engine -


The red wire with black stripe on the back of the key was hooked to the gray wire in the first pic which goes to the carberator. The plain red wire that comes out of the bottom left of the key in the second picture went to the red wire in the first picture.

As for the new engine, here are the numbers and pictures B&S 18 hp Twin II model 422707 Type: 121401 Code: 9404285B and I was told it came from a murray, don't know the model number


Here in the first picture is the black wire coming from the coil, which there wasn't one on the old engine. In the second picture is the red and white wire in and just to the right of the wires in the background in the candy cane shaped cut-out is where they go into the engine.

If you need anymore information or different pics, let me know

The wire going to the carb, you will u\just have to tape it off, the black wire coming from the ignition coil, you must make sure no voltage gets to it, or you will be buying a new one.

ok so i tape off that wire that went to the carb. The wire that comes from the ignition coil I just ground it or something? That will leave me with a red wire coming from the key and a red and white wire coming from within the engine. Any idea what to do from there?

Ok I think I got the wiring figured out. I hooked the wire from the ignition coil to a switch with another wire from the switch going to ground acting as a kill switch by watching youtube video. its not heating anything up or smoking the ignition coil like it was before i posted on this site. I ordered a new ignition coil, but in the meantime I can get it to turn over twice before it seems like there isn't enough power to continuously crank it. I'm recharging my battery and thinking about putting the starter from the old mower on the new one because the new engine i put on had been sitting about 2 years the guy said so I think its pretty close to frozen up.

Old starter doesn't mount the same way so I'll wait and see if this new coil and spark plugs work before I get a nee starter