basically if you are using the flywheel you need to cut the fly wheel fins down some people remove the fins completely even. make sure to balance the fly wheel upon doing that. the casing can be ground down to a certain extent on most engines. just dont make the mistake of accidentaly grinding away where the magneto pickup mounts or your flywheel is useless. i have seen some that converted thier engines for glow and removed alot of material so if you look at those for a guide as what can be removed again i warn you have to keep the magneto mount so you cant remove quit as much as others here. im not really all that sure about chainsaw engines because as far as i know chainsaws have more torque and are more powerful but i am not an expert there. the decal might be 2.3/16 as in 2.3 ci / 16 cc but that is not exactly right because 1 ci. = 16.39 cc but 2.3 is more like 38 cc or close to that. magneto engines are difficult to flip start really. when i tested my 25cc homelite i used my glow electric starter which turned the engine over just fine. as far as i have read on this forum you shouldnt have a hub longer than 2 and 3/4 inches. which is usally more than enough to mount the engine and get the hub out of the cowling. if its shorter i dont think with will hurt as long as it clears the cowl and the magneto flywheel is not rubbing on the inside of the cowl.