Of course, if you want to choose one of your own photographs, pictures or an image you find on a website as your background, find the image and right-click on its icon. Choose "Set image as desktop background" and it will become your new theme. To save it as a theme for future use, open the Personalize option again and click "Save theme." Now you can reuse it again and again without having to hunt for the original image. Air filter is blocked so there's not enough air input. There is a problem with motorcycle sprocket, like idling air inlet congestion, then the air input just isn't enough. The oil amount of float chamber is too high, some gasoline go directly into the cylinder without atomization, that may cause incomplete combustion. Main orifice wearout seriously and then this fuel injection from primary nozzle increases, that may cause incomplete combustion. Heating automatic valve is at start position along with the enrich valve can't be closed automatically, that can caused a wealthy mixture. Carbon deposit in muffler, exhaust jam, waste gas stay in cylinder, that can caused incomplete combustion then black smoke.