Join Date: Oct 2015
Location: Toronto, Canada
An engine won't start with little or no compression. It sounds like you have found you problem in that exhaust valve if its loose enough to spin when the intake is open Have you taken a clearance measurement?
My guess is that you have no clearance and the lifter is holding the valve from closing, which may be a simple adjustment by grinding the stem a bit. Could be more than that, like a bent valve stem keeping it from snapping shut too.
Since you are already in there, you probably want to check the seats, guides, and valve stems and lap the valves so that you top end maintenance is complete. Check for any bits of shrapnel in the spring chamber as well, in case something broke.
Work fascinates me.
I can watch somebody work for hours...
2008 Craftsman 944.528391 (It's a Husqvarna ST227P)
27", B&S 305cc 13.5 ft/lb Torque 9.5 hp