If it's a single, get the next "smaller" service manual.
If a twin, next "larger".

I'd suspect a blown head gasket??

"I can't seem to find a service manual on this particular model of Courage Engine"

Here's the web page for that engine... the last "S" doesn't matter when searching for an engine series.

http://www.kohlerengines.com/onlinecatalog/productDetail.htm?productNu mber=Courage SV735

And here's the service manual...

http://www.kohlerengines.com/onlinecatalog/pdf/sm_32_690_01.pdf

Sounds like raw gas in the exhaust and muffler. May be in oil too... check the dipstick.

Likely more than a valve adjustment. Check the push rods and make sure a valve hasn't dropped or stuck and a guide hasn't loosened. Maybe a blown head gasket.

This post was edited by justalurker on Sat, Apr 13, 13 at 21:10

Thank you for your responses !!