Yes, the part you've removed is the cooling air cowl. If you look closely at the cowl you'll find a very long string of numbers, broken into three groups, called the Model, Type and Code. If you post the numbers, we can tell you quite a lot about the engine.
Now you need to brush out all the leaves and dry dirt from around the fins and the ignition unit, before cleaning the outside of the engine in detail with solvent. Once the engine is clean, the next step will be a compression test, but we can talk about that when you've done the cleaning.
