you'll have to measure everything in order to make a decision about what to do w/ the cylinder and piston.
There are many different issues that could contribute to hard starting. Spark and fuel. Chipped or worn reeds could make starting difficult, too.
Check for spark. Make sure your fuel filter (inside the tank) is not clogged...take the fuel hose off and check for flow. If that's OK, check your reeds. While your carb is off, clean all of the jets and float bowl. If the reeds and carb look good, check your compression before you start tearing the engine apart.
Let us know how it goes.