Okay, So I have some time & cash to roll out and tinker with my 2T Yup 50 again..... Does anyone know what big bore kit is a direct bolt-on? I'm pretty sure it's an SF10 motor? Please correct me if i'm wrong? I see tons of 139qmb kits, but nothing for an SF10. Is the SF10 basically the same as the 139? I've read that these are decent engines? again, correct me if mistaken? I understand that most of you are not familiar with this model as there's not even a section for it on this forum. It's basically the same model as the "Sting", which is the UK version. Thanks