2006 Yamaha Bruin 250 - Carb Issue

[KevinWithNumbers]

About a year ago I replaced the carb on an Bruin that I bought from a relative, I replaced it because it was gummed up from bad gas sitting in it for a couple years. Replaced the carb, and ran it a little bit and it had a problem of the carb popping whenever giving it throttle. I assumed this was just a fuel air mixture I needed to adjust, but I was lazy and just let it sit for a few more months. I went to adjust it just now, but I don't know if I'm slightly retarded, but I can't find the fuel/air mixture adjustment screw anywhere on the damn thing. I've tried nearly every screw I could find on it without taking the whole thing off (Which is a pain on this atv). I'll link some pictures I have from ebay on this carb. I also checked manuals and diagrams of the carb and could not find anything anywhere. Please spare me from my complete ignorance.

[Frank Angerano]

Hey @KevinWithNumbers, welcome to Quadcrazy. 
Hopefully you held on to the old carburetor? If so great. Never let that go since oem carburetors are the best and always rebuildable as long as they are not cracked or striped.

I highlighted/arrowed where the air fuel screw is.  It may have a brass plug over it.  If so you have to drill the brass plug out.  Its pretty common to do this.  Some states require this cap for emissions reasons etc.    

Ive never had any luck with the $50 cheap aftermarket carbs from china.  They always have rough spots when you throttle up.  
Backfire issues etc. Just to finicky for me Hopefully you get lucky. 
If not then you can soak and rebuild the original carburetor.   We can help you along with that.