The manual says 2 liters, which is about 2 quarts and 4 ozs. My dealer told me the one Terra he changed oil on took 2.5 quarts to get it to the proper level. When I changed the oil on my Terra yesterday, I measured the oil I drained out and it was just shy of 2.5 quarts. I put a little less than 2.5 quarts in and checked the level per the directions in the manual and the level was just below the max level on the dipstick.
The manual says 0.528 US gallons, 2.112 quarts. I just did my first oil change and that's about what I used. I had put in more than that because nothing was showing on the dip stick, but once it was up to operating temp, it read over the max and I had to take some back out.
I wouldn't be measuring the oil when it's at temp, it's not going to give you the correct reading, wait about 1 hour after you turn engine off
While this may be correct for other bikes with a sight gauge, if you look in the shop manual accessible on this site, the procedure for checking the oil is to heat up the bike enough for the fan to come on twice and then check the oil while the bike is upright, aka not on side stand. The bike takes 2-2.1 liters almost on the dot with a filter change(check the shop manual accessible on this site). It will read low while cold when you first change the oil. But if you go rip around for 15 minutes, don't just let her idle through two fan cycles like the maunal says, it will still read low, aske me how I know , and check her she should be spot on in the top third of the dipstick. If you put in the 2.5 liters (ahhhhhh noooo too much by nearly 20-25%) someone else stated, you will have too much oil in there and it will read way over until to take some out and recheck while the bike is hot. 7500+ miles on my Terra, I've done all my own oil changes and overfilled grossly the first time, putting that extra .5 liter until I could see it on the dipstick when cold, this is not correct. Start with 2 liters and then ride around for a bit to get her up to true operating temp and check her again. She might need a hair more, but not anywhere close to another .5 liters