There is a certain order of priorities for upgrades.If you have the honda manual with the performance section in the back it lays it out in three stages.You don!t mention why you are opening up the motor in the first place so it!s hard to advize you on the next step.Get the manual if you can. they go for about 10 bucks on e-bay.I!ts the one with the rider on a 78 f model leaning into a curve on the cover.