[ducatiman]

I've encountered some rail filters scrunched up an inch or so up into the fuel line....creating flow problems. I stock EX500/ZX6 rail filters as they fit just a bit tighter...and stay put/don't automatically pull out with the hose when removing it.

Your rail filter may even be missing as they are frequently tossed.....but in the case of a midrange bog....I'd be more inclined to think the holes in the emulsion tube may be varnished up some. Pic.....PROOF the final catch rail mesh filters actually work.