1888a123_Beginner_Dirt_Bike___GICL_Wiki_Dirt_Bike_Parts_List_Function
[Part and Quantity] Engine Cover (2) [Part Number] DR70-118 [Materials] Metal, probably aluminum because of its light weight [Forces] No forces exerted [Manufacturing Process] Die Casting because of its fine surface finish and the residual risers [Shape] Rounded edges and hollowness of part lends itself to die casting [Part Complexity] 1 [Function] 
Functional/cosmetic: This part is a combination. It is used to cover and protect the engine from the rider and debris. It also hides the less attractive parts of the engine
Group 11 - Beginner Dirt Bike - GICL Wiki