valve-train

Hello, If anyone has at least one keeper laying around that they are willing to part with, it would be greatly appreciated. I've kept the 5mm stock valves intalled in the engine. I am putting together a mini bike for my son and this is literally the last part I need to have the build...

I have a GX160 that I am installing the Champion style shaftmount rockers, I have uncut cromoly pushrods and I and going to have .030 milled off the head. How do I make sure all these variables are set up correctly...? More specifically how do I determine the install height on the shaft...