mine runs like ass and im convinced theyre a shit carb design. I have change my fuel tap for a normal on off style one, upgraded cdi and blocked off the vacuum line on carb for the old fuel tap and it runs a lot better but im still convinced its 60% of what its capable of, and its super rich only runs with needle dropped in a new groove i made and with air screw all the way in. I am halfway through making a new manifold to fit a crf50 carby to it.

Should have let your son give it a good test drive on your backyard trail.