You beat me to it Rodney. If those valves arent set right you wil not get all the power out of the engine no matter what you do with the needles. Just be sure and either get REAL familiar with the procedure for adjusting or get some help. It is easy to adjust valves but you have to know exactly what the valve settings are and where to check them at in the stroke. Usually its at Top Dead Center, when the piston is at its highest point. Ill stop there because you really need to read your manual but its easy to do.

Needle settings are just like a 2 stroke as Minn said. If it runs great at full throttle but it doesnt idle well you can adjust your low speed idle settings but you need to read the manual on how to do it if you dont know how. More times than not the mfg settings are perfect but they werent set to mfg settings at the factory. Its just a good idea to learn and double check.