What does your owners manual say?
Here's the 2001 R6 pdf manual. http://www.yamaha-motor.com/assets/service/manuals/2001/LIT-11626-14-39_314.pdf
It says -
Without oil filter replacement - 2.5L or 2.64 US quarts
With oil filter replacement - 2.7L or 2.85 US quarts
Total amount (dry engine) - 3.5L or 3.7 US quarts
:cheers
Here's the 2001 R6 pdf manual. http://www.yamaha-motor.com/assets/service/manuals/2001/LIT-11626-14-39_314.pdf
It says -
Without oil filter replacement - 2.5L or 2.64 US quarts
With oil filter replacement - 2.7L or 2.85 US quarts
Total amount (dry engine) - 3.5L or 3.7 US quarts
:cheers