Re: how many liters?
If you give us the model number of your outboard, I'm sure someone will be able to tell you its displacement. Without knowing which outboard it is, it's not all that easy to guess.
It would be in the service manual for that engine, but there's probably an online source for the info, too.
I'm sure if you called your dealer and gave them the model number, they'd be able to tell you too.