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