I have one that was running straight gas. Would run but barely. Pulled cylinder to check it out and rings were stuck. Got one free and the other broke but I was hearing a grinding sound and thought bad crank. Turns out it was the coil rubbing. Reset and put it back together to see what it would do. No new gasket or anything and it fired up. Ran it for years and still running today.
Gas and spark is all you need. Even low compression it should run. Pull plug and lay it were its grounded and see what the spark looks like. Might be a bad coil. Before replacing take a business card and use that for a gap to reset with.