Four Stroke Cycle

Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!

First stroke. The moves down the cylinder with the inlet port and the exhaust port filling
the cylinder with a mixture of petrol vapour and air. This is the induction stroke.
Second stroke. The piston moves up the cylinder with both ports , compressing the mixture into the
combustion chamber at the top end of the cylinder. This is the stroke.
Third stroke. At about the end off the compression and electric spark is made to jump across a small
gap into the cylinder. This spark ignites the petrol vapour which burns very rapidly heating the gas in the cylinder
to high temperature and considerably increasing its pressure. The pressure forces the piston down the cylinder
with both ports remaining . This is the power stroke.
Fourth stroke. The piston returns up the cylinder with the inlet port but the exhaust port , expelling
the burnt gases from the carburettor. This is the exhaust stroke.