I'm having this issue on my 150px with a bgm bigbox v1.0 a 24/24e and a new 160/55 160/BE3/100 jet set . I'm at 9300ft so that's why I downjet 9 sizes from stock. I tried the 108 first but it was boggy and farty af.
The spark was nice brown w/100 but I had a severe flooding situation after a brief engine stops, no matter how brief. Lots of kicks and WOT for a sweaty Saturday and a lot of smoke! I see signs of oil/air? leaks at the cylinder 'neck' where the two parts match, and at the exhaust stub. While jetting, I screwed the mix screw all the way in and the bike kept running with the 160/55. The fuel gauge feels kind of stiff too. I recently replaced the needle but nada.
I then switched back to the 120/40 that was previously installed but the plug looks unwell. I'm gonna do the switch back to the 160/55 today as I suspect there's another reason for the bike to keep going with the screw all the way in. Until I can fix the cylinder leaks, maybe I'll try a drilled air filter I have on the 200 to see what happens. Probably try a 105 main jet with that.
The bike had a slight hesitation when releasing throttle and then accelerating again. It was gone I think with the new idle jet.
I have some new shims that are for the v2-3 bgm (didn't try the beer can shim) that I'll fix with some copper high temp gasket paste. I think I only want to apply it on the exhaust side and let the spring (currently uninstalled) do the rest of the job. Is this a smart idea or I need to paste it on the cylinder stub too. Is this a smart idea if I eventually have to remove it? I've read a slight leak is fine there, and this version of the exhaust has no tightening screw or clamp.