I am a super experienced 2 stroke guy and I have good news and bad news for you.
The good news is that with a few tools and a bit more investment you can have a really good ride.
The bad news is that as is the new chinese two stroke (48cc and 66cc) is poorly designed and needs some parts machined and some parts replaced.
Things you need to do:
1. Use sandpaper on glass to plane the head surface flat and increase its compression a little bit for more power. Also make your own head gasket out of high temp gasket material for it to seal properly.
2. Drill a bigger hole in the wrist pin for less vibration. Without this the engine will always be unrelible as it will shake loose nuts and bolts. Also a vibrating engine makes it uncomfortable to ride. If it still vibrates too much then you need to drill holes into the crank wheels with a 3/8" carbide bit.
3. Take the screws off of the stator coil and clean off the shellac on those screw head contact areas. That is important because that screw to metal contact is the ground path for the high voltage coil and spark plug. The worse the contact is the weaker the spark will be which reduces engine power.
4. Replace the stock nuts/bolts/studs with a replacement kit from Sick Bike Parts. The stock ones are too buttery and will strip threads and break off. Also apply medium strength thread lock to all threads.
5. Go to this page to read about the changes needed for the stock NT carb or the Speed carb if you have either of them. I prefer a Mikuni VM18 because it has a separate jet and air screw for the idle mixture. Also there are various needles available for it.
6. Replace the restrictive stock air filter with a bigger foam one that needs to be oiled with engine oil before installing. This will let the engine breath better for more power. The stock one is too restrictive and causes the fuel/air mixture to be too rich.
7. Replace the stock spark plug with an Iridium one (#7 for moderate climates or #8 for hot climates). This gives a more consistent spark at a lower voltage for smoother more powerful running.
8. Put a fuel filter on the fuel line because the filter inside the gas tank won't filter out the finer particles. Also there's usually trash inside the fuel tank that should be cleaned out before use. If not then that will partially block the filter and limit fuel flow.
9. Once you get these mods done and want the engine to start easier, run smoother, and have better top speed then think about putting a good carburetor on that is fully adjustable and also a good aftermarket CDI will help in the same way.
10. Consider removing some of the baffles in the stock muffler for better top speed.
11. The most technical mod you can do is buy a rotary tool with cutting discs and mod the cylinder ports for more power. You can widen the intake and exhaust ports and lower the intake port (or take some off the bottom of the pistons intake skirt) so that it has a bit longer open port duration (120 degrees) which gives it more power all around.
All of these mods are fully explained on this sites pages. Click the home link and start reading.