Thanks for your reply. When idle screw & low end needle are mentioned, do you mean clockwise or counter clockwise? How to determine when to stop turning the screw? By listening to the sound of the engine or what? Oh yes my engine produces a "rough, dry" sound. Does it mean it is lean? The G4S is no longer in production. What are the essential spare parts i need to get(parts that wear @ fast rate)? Are they compatible with G4RS? Thanks & have a nice day.