Here is the replacement cylinder head ATHENA Big Bore 80cc Ø50mm for KTM 65cc XC and SX. This cylinder head made of good quality aluminum allows a good combustion of your gas. However, following a strong heat the cylinder head can be warped and therefore not be tight anymore. In this case, rather than to replace the cylinder head, we strongly advise you to change it. Because it is a high compression cylinder head. If you overcompress it again, you risk a malfunction of your engine and especially a breakage of it