You may THINK that no porting is involved, but that would be an incorrect assumption. Boring out your cylinder WILL change your ports. Think about it.....your ports do NOT come in straight from the sides....they come UP into the sides of your cylinder. When you do a bore job, you move the point where the port enters the cylinder DOWN the cylinder wall. This changes your port timing. Whether it moves the power band up or down the RPM curve, I don't remember. But talking to a knowledgable engine builder (like Eric Gorr) will tell you and you can decide then if you need to have your ports done to bring them back to original specs or if you need them changed totally to deliver the power you want.