I'm new to riding and owning a quality motorcycle so please forgive my ignorance. Why must I have the valves inspected and if necessary adjusted every 12000 miles? I ride a 2013 F700GS and am very pleased overall with it but a little surprised at the upcoming service cost. My 4 wheelers don't need this and last forever and some motorcycles don't need this. Also, what would happen (in theory) if this service was ignored? Thanks for your consideration of this topic.