[Oddball Matt]

Anything`s possible at this point but a whole bunch of symptoms point to the mixture being way too rich:

-sooty plug

-hesitating coming off idle

-misfire/bogging past half throttle

-idle mixture screw does next to nothing. Fully closed the engine dies, other than that setting has little effect

-exhaust fumes reek of petrol

Based on my studies of late ALL of these symptoms can be explained by a too big pilot jet, and remedied by fitting in a smaller one.

the kids made sure I never made it to the garage to try running the quad without the exhaust but based on my findings so far I`m fairly certain the answer here is a smaller pilot jet, which I will be ordering once I send this post. Results to be reported come next weekend.