sounds like what I just did only slightly less worse. When I put on my head my adjuster screw got behind the valve and bent it. I ran horribly and better at higher RPM, backfired and what not. I noticed that the spring was compressed and the rocker was loose, the proceeded to used sailor talk<img src="/forums/images/graemlins/ignore.gif" alt="" />. I'm actually surprised it ran at all.

I would take a close look at all your valves and see if one is not in the Down position. They may be functioning but a leak down test will verify if there is air leaking in.

Good luck. <img src="/forums/images/graemlins/kewl.gif" alt="" />