My Gilera 180 SP won't start?

I own a 2 stroke Gilera Runner 180.

I have had it for 5 years now and approx a year ago I had a problem at full speed. The problem was that when I was reaching a certain speed (80kmp) the engine would die, if I pulled back on the accelerator and went at 79kmp it would go ok but would die if I accelerated any faster.

Because it was sat for a while without being started, I charged the battery and tried starting it up but with no luck.

I changed the spark plug, oil and drained and the old petrol and put in new.

Still with no luck starting.

I took off the carburetor and gave it a good clean and put it back on, tried starting but still with no luck. Should there be fuel in the area where the bouy is? because there doesnt seem to be.

I put a bit of fuel in the carburetor and with luck it started but as soon as it got used up it would die.

I took all the panels off and checked the wiring and pipes. Everything seems to be ok.

There is fuel in the 2nd small tank that leads from the main fuel tank. Every time I kick start, fuel enters the 2nd small tank.

If I disconnect the fuel pipe that leads to the carburetor, fuel comes out.

Any help would be much appreciated.