I am new on bike wrenching but the decomp solenoid opens the exhaust valve during the initial spin of the starter so the momentum of that one big piston can get going without the load of engine compression. it then lets the valev work normal so the engine will fire and run. Out of adjustment will keep the valve from opening putting to much load on the starter or keep the valve open all the time causing low power and burning a valve. My first time to check mine I didn't have a clue. The pictures in the factory manual stink. I cruised thru a multitude ot postings until I saw one that makes since. To check it reach under it and clamp it in your hand. It will push the plunger thru the solenoid so you can measure it. You check it at top dead center as if you were going to adjust the valves. Hope I haven't confused you too much.

The chain book stores sell a book called 'Idiot's guide to motorcycles'. I don't remember if it has a chapter on just singles but it's a pretty good book . I was to cheap to buy one, about $30 if I remember right. But go to Barnes and Noble, buy a large coffee, find the book and read away. I just kept readimg the sight here until it all clicked (somewhat). You learn something new evrytime you check-in here!! Welcome aboard to the Savage world.