Once the fuel cams have moved, the engine can then start running in the reverse direction (anticlockwise). Because the engine is started using compressed air admitted through the air start valves, the operating mechanism for these must also be retimed. The angle that the cams move through is the lost motion angle.
How do ship engines start?
One fuel is introduced, the engine is run up from essentially quarter to half throttle a couple of times, and then run wide open. Only after this time-consuming process is completed and everything is in the green can the propellers actually be engaged, and the ship is able to get underway.
Can a 4 stroke run backwards?
No. If it was running backwards, it would expel the fuel rather than sucking it in. On a 4 stroke engine, air enters through the air filter, goes through either a carburetor or fuel injector, air & fuel is mixed, then drawn into the cylinder through an open valve.
Is it possible for an engine to run backwards?
Absolutely. The engine can spin backwards if there is a force spinning it that way. There is a good chance that anything belt/chain driven will not spin backwards as the belts/chain can lose tension or not function correctly going backwards.