The oil drain plug on a 1985 Honda Nighthawk 750S is located on the bottom of the engine casing, just below the oil filter. It is a 17mm bolt that can be loosened with a socket wrench.
To change the oil on a 1985 Honda Nighthawk 750S, follow these steps:
1. Place an oil pan under the drain plug to catch the old oil.
2. Loosen the drain plug with a socket wrench.
3. Allow the old oil to drain completely.
4. Replace the drain plug and tighten it securely.
5. Remove the oil filter.
6. Apply a thin coat of new oil to the gasket of the new oil filter.
7. Screw the new oil filter onto the engine and tighten it securely.
8. Add new oil to the engine through the oil filler hole.
9. Check the oil level and add more oil if necessary.
