If you look inside your carburator, by removing the cover, you will see a slide that floats free, and that is free of the accelerator cable. It is free to slide up and down, and actually kinda flutters up and down, while the engine is running. I think this may be causing the ticking sound. You will need to look for yourself to see what I am saying. I am not sure of what it is called but I do know it is free floating and flutters free with more air flow, hence more with higher acceleration.