If you don't have the owner's manual, you can try these alternatives:
* Yamaha's Website: Check Yamaha's website for downloadable owner's manuals. You might need the model number (precisely) to locate the correct document.
* Online Forums: Search online forums dedicated to Yamaha motorcycles or classic motorcycles. Someone with experience with that specific model likely posted the information.
* Repair Manuals (Haynes or Clymer): These aftermarket manuals often contain detailed specifications, including oil capacity.
Keep in mind that the capacity might vary slightly depending on whether you're just changing the oil or also replacing the filter. The owner's manual will clarify this.