You can also on most engines just watch the valves. If the intake is just starting to open its safe to do the exhaust. This guy acted like he was only Book Smart. By watching the valves can tell if you on 1 or 6 top dead center. 4 cycle engine=intake 1/2 revolution--compression 1/2 revolution--fire(power) 1/2 revolution--exhaust 1/2 revolution