I purchased a SenDEC STS 5000 (shop tach) in order to optimally adjust idling RPMs on my 2007 15 HP four stroke Honda. Instructions direct that I preset the shop tach at P1 - 1 spark: 1-16000 RPMs, or P2 - 2 sparks: 1-8500 RPMs, or P3 - 1 spark: 2 - 16000 RPMs. I don't understand which setting I should use and why. Any help/explanations would be much appreciated. Thanks in advance.
