If you want more power, there are many possibilities. You can tune without adjusting your displacement, such as changing cylinder heads, camshaft, etc..., but you can also increase your displacement. This can also be done without sump adjustments (slip-in cylinders), although you may be limited in terms of displacement.
For a larger displacement, you will have to adjust (machine) the crankcase. If you need a crankshaft with a longer stroke, there is a chance that you will also have to machine the inside of the crankcase. You will understand that this requires more work.
All cylinder and piston sets with large bore (big-bore) are supplied complete with 4 pistons, 4 cylinders, 4 piston rings, 4 piston pins and safety clips. The dimensions indicate the space required in the crankcase or cylinder head, so the cylinder size is a smaller fraction.
