For the original poster, as someone has already noted, at WOT (Wide Open Throttle) the man jet is responsible for the mix, the needle controls the mix in the mid throttle region. If you are looking to effect the way your bike runs at WOT you would need to either adjust the main jet size, or adjust the air flow by tuning the muffler and/or air filter.
One thing I haven't seen mentioned here, if your carb is not mounted level you might benefit from doing a little float adjustment. Sometimes when a carb leans in toward the motor it can make it run rich, adjusting the float to maintain a LOWER fuel level in the bowl may help lean out your mix a bit and give you a bit more power at WOT.
For the newbie that is reluctant to take apart his carb and tune it... You're gonna have to take it apart sooner than later just to clean it, so might as well bite the bullet and dig in! There aren't many parts inside and it's not that complicated (to assemble at least, understanding how it actually works is another thing). Just make sure you work on a clean workspace and keep track of the few small parts from inside. Taking pictures with a digital camera as you rip things apart is also a good suggestion also....
This is a hands on hobby, these Chinese motors are not particularly reliable, if you don't know how to work on them you probably wont be riding long... When I first started out I read someone here say you should have desire to dig in and work on your bike, if you don't have that desire then you should probably just buy a scooter. I didn't understand at the time, but now I do. If you don't enjoy wrenching on your bike this is gonna be a miserable experience for you, if you just want cheap fuel efficient transportation then a scooter is more appropriate....
I'm not trying to say anyone here should go the scooter route, just trying to say that wrenching is REQUIRED on a home made MB, but not on a scooter. If you ride a MB get used to wrenching, embrace it! LOL
PS I don't recall seeing noted what kind of carb you guys are running, that makes a big diffrence as the NT or Speed carb only has one jet while the CNS carb has three....