I want to colour paint in my bike ?????

Actually i have old pulsar 150 i want to colour paint but only i want to colour paint in engine & alloy wheels but now my bike engine colour is silver i want to colour it in black so mechanic will remove my engine & then paint or he will paint it as it is ......if he remove my parts & paint it then my will affect ......how he will paint my bike ............please suggest.........me