XJ650 Maxim carb diaphragm question

Finished with my first carb cleaning, and other than having to replace a float needle, I noticed during my clunk test that two of the pistons (when the hats are replaced) clunk faster than the other two, and I don't encounter as much resistance when pushing the pistons up on those two carbs (there is SOME resistance, but not as much as the others). There are no holes in the diaphragms, but I'm wondering if maybe they've gotten stretched (one of them was installed improperly by a previous home mechanic - part of the diaphragm was folded back on itself, so there was no vacuum happening on that piston). I haven't gotten the bike running yet, but before I put the carbs back on, I was wondering if anyone else has ever encountered this, and if it's something I should be concerned about. Do I need to replace these pistons and diaphragms, or should I only be concerned with ensuring a good clunk when the hats are removed?

Thanks,

Bill

 

Level.
No Hats ... No Springs.

They should all Fall without resistance.

If they vary a bit after testing, ... make sure the Diaphragm remained seated during the Hat install.

 

Thanks Rick.

If the diaphragms remained seated after install and there is still some variance, do I need to replace the pistons, or will the carbs still function adequately?

 

If they fall nice during the OPEN Test, ... a "Variance" might indicate:

A Pinhole Leak in a Rubber.
A Return Spring not applying equal force.

If you still have them off the Bike, see what happens when you hold the Vacuum Cleaner Hose to the Carb with the Throttles Open.

Apply Vacuum.
Remove it.
Watch the Piston.
If it hangs-up, ... the Bore might need more work.

 

Given your experience that there is a different amount of resistance when pushing the piston up against the spring, maybe try to take the springs out and measure to be sure they are the same length, and same thickness.