Yeah, for our purposes a Liter and a Quart are close enough-- 1 Liter = 1.06 Quarts.
I agree with siai47 about oil changes. I warm the tranny with a good 20 minute ride to warm and thin the oil for improved removal. I put the bike in a wheel chock (upright), drain the oil well, replace a clean plug with a new crush washer, fill tranny via the vent, 1QT of Amsoil Metric SAE 10W-30 (wet clutch compatible) as recommended by Brammo. This oil yields a smoother operating transmission. I have measured the removed oil several times-- always yields 1 QT. So, I never both to remove the overflow plug either....