So it ran properly for the first time with a complete exhaust system. and it made a horrid knocking noise.
so I opened the top and found that the needle bearing had collapsed and caused this
Also knackered the camshaft. So much love for the T**t that sold me this engine. I've ordered a new camshaft and relevant bearings/ seals. It'll get done eventually, most likely in summer due to looming exams. This is my current state.