Bayou 220 noisy engine
I've completely rebuilt mine with .040 over and milled the head .050 and new valves. It made a knocking noise before and after the build. A while ago I did some research and concluded those 220's just do that. It kinda sounds like piston slap to me.
And about the valves, I backed off the intake lash quite a bit and gained some HP. Now it makes a clicking sound, but runs better. Took the baffle out too, its not that much louder, but runs a bit better.
The decompression lever should be down I think. Pull it up to open the exhaust valve a bit. As far as pulling the head, its pretty easy. The hard part is getting the rocker shafts out. You have to use the cam bolt and a metric nut to make a puller.