An engine, in order to start, needs a good cranking speed, good compression, the right amount of fuel inside the cylinder at the right time and a good spark at the right time. An engine that doesn't start has one of those things missing and it is pointless guessing which.
The spark plug is probably the easiest to check to begin but it is folly to replace it without checking the spark as part of the process.
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An engine, in order to start, needs a good cranking speed, good compression, the right amount of fuel inside the cylinder at the right time and a good spark at the right time.
An engine that doesn't start has one of those things missing and it is pointless guessing which.
The spark plug is probably the easiest to check to begin but it is folly to replace it without checking the spark as part of the process.