151 Engine Service and Repair Technician Handbook The 4-Stroke Cycle Nikolaus Otto invented the basic 4-stroke internal combustion engine in 1867. Although modern engineering and electronics have completely revolutionized engine technology, today’s engines still operate on the principals of Otto’s 4- stroke cycle. The four strokes are: • Intake Stroke • Compression Stroke • Combustion (Power) Stroke • Exhaust Stroke 10 Technical Training