Message for Beginners

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) are poorly designed and need some parts machined and some parts replaced.
Things you need to do:

Enhancing the stock setup (do these before spending big money on parts and porting the engine)
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. If the engine vibrates then 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 which is explained on this page.
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 more professional carbs with a separate jet and air screw for the idle mixture but the NT is OK for beginners with the stock piston port only intake system, and the Speed Catb is good for reed valve engines.
6. Replace the no-good stock air filter with a bigger foam one that needs to be oiled with engine oil before installing. You can make your own out of carwash foam. Just use scissors to hollow it out and make it sized right to clamp it onto the carb intake. Also you can glue pieces together with silicone sealant but you can't ever clean it with gasoline or it will ruin the sealant.
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. Cut off the majority of the exit pipe inside the muffler. (actually even doing that is not enough. It really needs to be replaced with an expansion chamber.) Click here to read more.

Once you get these mods done and want the engine to start easier, run smoother, and have better top speed then think about the following possibilities:

Making It The Best It Can Be
1. Get an exhaust pipe that is an expansion chamber. When its length is correct (16" centerline from piston to beginning of baffle) for a stock engine it will boost engine power for another 1300 RPM right when the engine by itself would poop out. Click here to read more.
2. Put a good carburetor on that is fully adjustable such as the Mikuni VM18 or Dellorto PHBG17. If you port the engine and balance the crank then you might consider the Oko 21mm carb. Click here to read more.
3. Put on a good aftermarket CDI that will help the engine rev out. The best one is my Performance CDI, and second best is the Lightning CDI.
4. 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. Click here to read more.

All of these mods are fully explained on this sites pages. Click the home link and start reading.