Could you tell us what the problem is you are trying to fix.... Hard start, no start, delayed start, cranks too slow, cranks but no fire... etc etc. If the negative wire is getting hot, it could be due to any number of issues. I would look for a loose connection or corrosion on a terminal end causing excessive resistance first. I'm assuming your engine is stock with no high compression pistons etc. A wire size too small will get hot. Low battery voltage will cause it. Cranking for too long. Cold engine with oil too thick. Failing starter etc etc. Give us some more info so we can help. Oh, the negative cable terminates on the left rear of the engine. It doesn't attach to the starter.