The engine with the dark blue cooling shroud that has spots of yellow coming though is a 5HP Briggs and Stratton engine. However, I understand that the other engine that is missing a carburetor is a Tecumseh engine. I am unsure of the model/hp of the Tecumseh.
From the pictures, it looks like the Briggs engine you have is a Raptor, which is a great, strong motor for karts/minibikes.
Both look to be in great shape! But it is important to clean out methanol motors after they are used as I understand that the methanol quickly corrodes aluminium. Someone with more information on the subject will be able to better inform you on that.
-Jack