tmxpro80 66cc running bad

Hello guys, been lurking through the forums for a while now looking for all sorts of fixes.
I've purchased a generic 66cc china tmxpro80 brand off ebay here in Vic a while back and have sorted all issues out.
Tops out at 45kp/h stock on a straight road at high rpms, although doesn't sound too good going that high.
I don't know how you guys get close to 50mph + in America, my 120cc pitbike manages to top out at that much, so i call BS.
This thing is adjusted to the leanest c-clip setting and is still running rich and bucking like no tomorrow when keeping a steady throttle and low rpms.
Full throttle and high rpms (which is the only thing that will move the bike with me on it ) it 4 strokes like no tomorrow.

Apart from re sizing the jet which is a very tiny job for my big hands, and purchasing a boost bottle or jet from the US for $15 + shipping on a product that costs less than the actual shipping, is there anything i can do to make it run leaner and not 4stroke.

 

that is slow, but may improve after a few hundred miles, unless a lot of weight is being pulled

 

You need to rejet the carb. The stock NT carb has 5mm jet, available from many sources including Sick Bike Parts. Don't know your altitude there (mine is 900ft) a #66 jet is a good place to start. (stock is #70) They jet these things rich at the factory so they will start easily. Another trick is to build up the thickness of the needle with solder, leaning out idle and cruise mixture, but doesn't do anything for wide open throttle which is controlled solely by the main jet size. One other thing to try is lowering the float level, if it is too high it will cause a very rich mixture. I run a #64 main jet with the needle set in the second groove, and it pulls like crazy.

 

My bike doesn't go 45 k/ph with a serious tail wind up it's backside. Max speed is exactly 20 k/ph (12,54 mph) as per the generally understood regulations.
Even if i throw my bike out of a Cessna 174 at 2,000 feet, it still won't exceed 20 k/ph because the regulations are more powerful than the force of gravity.

 

Not a lot of people are running 50 mph bikes, but the ones who are have spent a lot of time and money to get it that way. I top out at around 48 mph and it took new higher quality bearings, a hand-picked crank, a lot of port work, and a huge 19mm carb to get there. the absolute fastest stock 66cc engines top out around 34 mph