11 Hp Briggs Intek Compression Question

How much compression should an 11 hp Briggs Intek have cold? I understand they have a compression release system that allows for easier cranking. The engine has always cranked and ran flawlessly until Saturday. The engine for some reason way oversped. I shut it down to inspect the throttled and guvnor linkage which is still intact. Afterwards I tried to restart it. All it will do is make a popping sound and puff white smoke. The valves are still in adjustment. No gas in the crankcase. I was advised to get a compression tester and go from there. So I guess the bottom line is. What's the minimum amount of compression I can have for it to start? If anyone has any idea why it oversped or any info in general. Feel free to comment. I can clean a carburator, adjust valves. But that's about all the experence I have. Thanks in advance.
 

First on the compression numbers the minimum is around 70-90 psi. But a leak down test will provide better info on the cylinder condition. Lots things could have happen and with it acting as describe can even have timing issues now on top the initial failure.
 
The over speeding was caused by loss of governor control. If this use the mechanical governor as many of the Inteks do then if linkages are tight (no loose retaining screws) is likely that the governor itself failed.
 
Engine info would nice like the model, type, and date code numbers as we can look exactly what your setup is.
 
Personally I would recommend letting someone familiar with small engine have a look at it. A experienced mechanic can do non invasive tests where a DIYer would need to disassemble the engine to check things.