need more info-2 stroke or 4 stroke, engine in bike or out? Cylinder head off bike or engine all togther? See the problem is that you will pay for all labor at the shop needed to get to and remove the piston, if it is a 2 stroke generally it is a little cheaper, IF you replace the piston, you also need new rings and to have the cylinder honed before reinstall of everything. If the previous piston caused damage to the cylinder walls then a new sleeve has to be installed and then the other work done.