Factory says 30 top 60 bottom, for me this is to much. I suggest half 15/30, there are many variables to account for, race conditions, fuel and oil used, mixtures, carb setup, temps etc. I do know many club guys have seen the numbers the factory states, but I have always cautioned on the side of maintenance is cheaper than repair, no matter what brand it is. Someone also stated above about the cylinder liners, these are to help with reliability and repair costs, but as stated they do become out of round, so its important to make sure these are honed properly with regular maintenance. If you want to do the assembly work yourself, make sure you have a known shop do the honing and piston fit for you, its worth every penny and honestly they charge $60-$75 for this work so not a huge cost.