Hi, Is your bike stalling and you cannot figure out why. I have had this problem, for me it has always been a problem with the fuel/air intake. What you want to do is look at your air filter and see if it is dirty if it is then there is no air getting into mixed with your gas and to make fire you need fuel spark and air.
If you do not have all three your not going anywhere.
1. Check the air filter if it is covered with dirt chances are there is no air getting in. If you have a K&N style air filter you should buy the K&N air filter cleaning kit.
2. Take off the carbourator and take it apart clean it through and through check all of the fuel lines and fuel filter.
3. The first time this happened to me i was told to clean the carbourator and I did twice, and it did not work. So on the third time i took it off i Took apart the fuel on/off valve and noticed the 4 rings in there were mis shaped which meant that there was no fuel going into the carbourator. What you want to do is if you have this problem is to take something like a pen and reshape those holes.
It is very simple to do
4. One other thing is to check the spark plug. What you do here is take off the spark plug. Still have it plugged in and hold the bottom of the spark plug to the head of the engine; And pull on the starter if there is no spark then you need a new plug.
One other thing that is a given make sure you have fuel. Now to start taking apart the carbourator this is what you do.
(i did this while my engine was out of my bike for better photo's this may not be the same for you)
1. Locate the air filter on your engine, yours may not be the same as mine. If you do have the same as mine loosen the hose clamp and pull off the air filter.
2. once you have that off you will see 2 star head screws on the left and right, loosen those off.
3. While you are at this step you may want to tighten your choke. You see that oval shaped metal with the hole in one end and with the nut on the other end of it. Next you will see 2 black alan key screws on the left and right again loosen those off. Once you have those off you can now take off the carbourator.
(befor doing so there is the throttle cable and the gas line that you need to take off that i coulnt not show in this situation) 
4. Once you got that down you may now take off the float bowl.
BE CAREFUL THERE MAY STILL BE GAS LEFT IN THE FLOAT BOWL!!!
Just take off the 2 screws on the left and right you do not have to take off the one in the center.
5. Now you will see the valve there may be something clogging in there to let no gas into the float chamber so to check so this is what the valve looks like when it is closed.
And this is what the Valve looks like when it is Open.
6. Now to check if there is gas getting through there blow through gas on/off valve located on the top. If there isnt then you need to take off the gas on/off valve which is located on the base of the carbourator. You are only able to see one screw of this picture but there is another one of the other side. Now take them off and blow air into the hole that there is this should definatley clear whatever there may be in there.
While you are at this step you may want to concider cleaning out the carbourator take a air nozzle and blow air into ever single crevace that you can here are some "sweet spots"
Blow air into where the throttle cable was.
And now blow air all over the choke valve and all other surrounding areas. Just blow air anywhere that you can.
Now you can put it all back together!!!!
7.
Make sure that you put your float bowl back on in the previous step. You take those 2 long black alan key screws located on the left and right, and screw the carbourator back onto the engine
8. now you screw this back on with the 2 star screws located on the left and right (i am not sure the termenology of these so could someone please p.m. me what this white thing is called)
9. Now you can put the Air filter back on a tip is to clean the air filter so you can get some more air into er' and go faster.
TADA!!! you have just cleaned you carbourator and here is what it should look like after.
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When i first bought my bike huckster told me that incase if there is gas leaking out of the hose that goes under the float bown that all i have to do i tap it with a hammer or the handle of a screw driver. AND I AM ALL SELF TAUGHT ON THIS