You should look at the carburetor if it has manual or electronic low, the electronics connects to the high coil, if it does not work on a low drowns and in high resurrect, if it is manual it is evil regulated, it is a simple chicler, but you will have to regulate the carburetor in low and very hot the engine to stop failing, you are missing air in the regulation of the low. The Royal Mescla is 14 from Nafta Air