As you close the high-pace Needle Valve, the engine will begin to run smoother and the RPM's will rise. The engine will proceed to speed up as you close the needle valve until you pass the optimum fuel setting. At this level the engine will begin to decelerate as you decrease the gas going to the engine as it is now too lean. When this happens, instantly open the needle valve a couple of clicks! In case you run the engine at a lean setting for quite a lot of seconds it would damage your engine.

Ball Valves

Check Valves

Butterfly Valves

Safety valves

Reducing Valves