I think you have an Intek V twin but need the type number.
Now if it is an Intek the compression numbers are too high for a cranking engine as this engine has an ACR system that limits the compression. With Intek engines that usually means the rockers are out of adjustment. So check the clearances. .004-.006 in.
It does sounds like a lean burn issue. Have you tried applying a little choke to see if it will smooth ou? Note some has an air vane auto choke system.
As being the Nikki make sure the main jet is not loose. And it is clean.
And the SM doesn't cover the single barrel carb set up. Briggs should update their manual but they apparently too darn lazy or too cheap.
