hi, my sp150 have serious leaking of petrol when on side stand. Within a day, half a tank of petrol is leaked away. Any idea of this problem? I have went to bike shop, they serviced the carburetor, and also ask me to switch the fuel valve to Off mode when is stationery. I have tried it yesterday and going to monitor further. But i have concern will there be more problem if i constantly need to adjust my fuel valve?