Clunk test clarification

Doing my first carb cleaning on my XJ650J, and just finished my first clunk test on one cylinder. With the hat off, the clunk seems fine, but with the hat on, it no longer clunks, but comes to rest slowly. The threads I've seen all indicate that the clunk test should be done with the hat off, but I'm wondering if I should be concerned about the lack of clunk once I put the hat back on. Any advice?

 

Once the hat is back on, the diaphragm chamber has to fill with air as the slide descends, so the "clunk" isn't much of a clunk anymore. More of a soft landing.

 

Do you put the spring in? If the diaphragm is sealing properly with the hat installed the slide has to pull air that is displaced through the tiny holes in the bottom of the slide so its not going to drop as fast. There seems to be a lot of misconception as to how these carbs actually work check out these videos :
http://xjbikes.com/Forums/viewtopic/t=29091.html

 

Recalling my own experience, the pistons did indeed fall with a clunk when the spring and hat was off, and slid into position with a much more attenuated clunk once the hat and spring were in place.

Look out for pistons closing slower than the rest when doing the test with the spring and hat in place.

 

Yes, I put the spring back in - my concern was initially around the fact that carb number 3 was clunking with the hat on (before I cleaned it), and it turned out that the diaphragm just wasn't seated correctly on that piston, so it was falling faster than it should have. Makes sense now - thanks to all for the help!