hello was wanting to know how to tell what size an engine is. I have a new engine case only, it is a picco. I have a pic of it, thanks

Ussually it will say on the side of the case, either 2.1 or 3.5 (.12ci or .21ci). That case looks like a .12 to me, Ive had a couple of those.

measure the width of the bore/cylinder, obviously you probably won't be able to measure exactly but you will be able to come close then compare that to the specs of the bore and specs on picco's website between the 21 and the 12.