I'm new to the site, and I have a 400ex that I stuffed an xr650r into. The stock bore is 100mm, and I can get a 102.5mm kit that puts it at 680. Since the top ends are so similar to the xx, I bought a 700 cylinder, to start off at 686. The only mod I have to do to get the cylinder to work for me, is put an "aluminum gasket" of sorts, to space the cylinder upwards a bit. I already have those measurements, and I'm getting ready to mock it up on my spare motor. Since I already have a 680 xr jug, I want the xx to be bored out to a 105mm. I've only seen a few kits, but haven't found any good info on whether or not the stock sleeve can handle a 105. I'm going to use the xr head, and the xr rod and bottom end. Finding a 105 piston for the xr shouldn't be an issue, I am just trying to find out whether I need to resleeve or not.