2004 vfr800 front cyls low comp and knock noise

i have a 2004 vfr800 9900 miles just bought it at 8800 miles a two weeks ago. changed oil three times for a good color. also changed plugs gutted exhaust baffles,pair and flapper mod. was out riding today and lost some power when i got home min later there was a knock at idle. any ideas.. is this something i can do. i have built a vf750f not anything like this.. please help

 

front cyls have very low comp. back cys have great comp. my craftsman comp tester kit wont fit in the plugs threads not long enough?

 

Cams look perfect. Cyls on Front make thump noise very low comp whats the deal. Bad valves