Check this page for sample displacements.
To install such a kit, you must pull the top end. Acquire cylinders with flat decks. Press the sleeves out of them. Bore the aluminum to accept a larger sleeves. Bore and hone these to accept the larger pistons. Enlarge the spigot hole to accommodate the larger sleeves. Ride only short distances and very gingerly to avoid heat-related problems. For a 108mm piston, a sleeve OD of about 112mm would be required. A deck flange with an OD of 116mm would be called for, with a depth of at least 2mm. There's room. One would only need to remove material from the cases down about 20mm.
See 102mm for further information.