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Carb Float NeedleThe next area for fuel control is the carb float needle. If your gas valve tests good, or has now been repaired or replaced and tests good, we will move on to the carb float needle. The fuel valve controls fuel when the bike is running or when the lever is in the off position. The carburetor float needle stops excess fuel at the float bowl. The needle has 2 tabs or ears on the end that enable it to sit securely in a notch on top of a brass or plastic float {see photo below}.
In the absence of gas, the float moves down, allowing the needle to let gas in, filling the bowl to a specific height. The rising float lifts the float needle into the needle seat, sealing off the gas entry point. When a carburetor float needle gets corroded from old gas, or fails, it can no longer move freely into the needle seat. It can get stuck outside the seat, effectively, in the open position. This allows gasoline to overfill the carb and run down into, and flood, the engine. See Why is fuel inside your engine bad? on the
previous page. The float may also fail. Floats can develop pin holes or minuscule cracks that let fuel inside the float. This makes it heavy, no longer buoyant, so that it can no longer "float" up and down. If it can not float up the fuel will continue to enter through the float needle. The float needle and seat together, are often called a float or needle valve assembly. The carb float bowl needs to be removed so that you can check the condition of the float and needle. I did not have a DR200 carb to demonstrate but I had a set of old crusty Honda CB450SC carburetors to work with. You may try to do this with the carb still on the bike. I took the carbs off & put them on the work bench to make it easier to photograph. If you do not take the carb off the bike, make sure you drain the float bowl before taking it off. Just loosen the drain screw and let the fuel run down the drain hose.
Locating the Carb Float NeedleFirst, remove the screws that hold the float bowl to the carb housing. If the bowl does not come right off, you may need to thunk it with the handle of your screw driver to dislodge it. Now you can see the float. 
It is attached to the carb body with a long thin pin on which it pivots or floats up and down {see photo at right}. You need to tap this pin out. Place the tip of a pick or super thin screwdriver on the end of the pin and lightly tap the handle with a small hammer. If your tool is too large to tap it all the way out, gingerly grab the other side with pliers or vise grip. You want to hold on to it but not grip it so tightly that it becomes deformed in some way. It needs to go back in when you are done. Holding the pin in the plier or vise grip jaws, tap the tool with the hammer to pull the pin the rest of the way out {see photo below}.
The seat is in the carb housing, under the float, just in front of when the pin was. The float needle may be stuck in there. Use small pilers to grip the end and pull it out. Don't worry, it can't fall all the way in. The 2 side-by-side photos above show the needle in the seat (left) and an empty seat (right). Next, check to see if the needle slides freely in and out of the seat. If it does not, that is most likely the source of your fuel problem. Cleaning the Carb Float Needle & SeatClean the needle with carburetor cleaner and a soft toothbrush or cloth.
In the CB450 set of carburetors we used for the photos, the end of the carb float needle that sits in the notch in the float was corroded. The photo below shows the carb needle we removed next to a new needle.
So in the CB450SC carbs, the needle moved in the seat easily, but was no longer hooked to the float. The float moving up and down no longer controlled the needle movement and therefore the needle no longer controlled the fuel supply. If your needle is damaged in this or some other way, it needs to be replaced. You can purchase a needle and seat together as an assembly, but sometimes, especially with older bikes, all you can get is the needle. Replacement Parts
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