No1kimchi

Hi guys. Got 2018 txt 250 and tried to replacing the top end but I really can’t find way to how to tighten front cylinder base nuts. Plain ring wrench doesn't fit at all neither most slim wrench(signet 30493) I got. Was tried to tighten with open end wrench but seems like nuts are gonna stripping. Any idea how to tighten these nuts with torque spec??