You know sometime's it's something simple that we tend to overlook.With that being said and reading all what you've done I can say it's got to be a hair puller for sure.Sorry for not really being able to give you any more idea's. I'll be watching to see what you find out,as stuff like this is interesting too me.For a example on my MF 1655 with the Honda 20 hp V-twin it would start up fine about 4 or 5 times then it would take forever the next time pop and backfire then finally start. Checked everything out ,fuel, spark etc: did this for over a year untill finally it wouldn't start. Then I was able to figure it out as it had no spark on one side .Faulty coil on the one side,the worst part was that it was intermitent and when I checked things out everything worked fine. Like I say it's a hair puller for sure.I know you've done lots already and will continue to do so untill you get it solved so ,Good Luck Chuck and hope you don't pull all your hair out before getting to the bottom of the problem.LOL Larry
Larry I have been pulling my hair out. After trying what I had and talking with Daniel,I had a feeling about the compression , but I think I was trying to deny that since it would be more work than just replacing a faulty condenser or something else easy to fix.
I will be pulling the head soon. This week is busy, dont know if I will make it out until saturday morning.