I have a lawn sears mower with a 4.5hp B&S engine that run real rough. I changed the gas, new plug, new air filter. I think I messed up the needle valves on the carb. There is one on the bottom and one on the side. How do I know the adjustment for each if I was starting from scratch. Do I turn them all the way in then back them out a certain number of turns?

Dave, January 2006

Turn them both in until they just seat. Not too tight or you'll damage the needles! Turn both out 1-1/2 turns. The engine should start at that setting. Allow it to warm up for about 3 minutes. Start with the bottom screw and the engine set at fast speed. Turn the bottom screw in slowly until the engine starts to run rough, then counting the turns, turn it out slowly until it starts to run rough again. Then turn it back in half way between the rich and lean settings. Then set the engine at idle and do the same process with the screw on the side of the carb.

Rick, January 2006