I agree with AlfaJack, it is most likely air stuck in system. I found this with my '94 Civic. Haynes manual says that ABS systems should not be bled by home mechanic, but I ignored that. It just seems to take a little while. The fluid can come through without bubbles, then suddenly when you think you're done, a bubble will appear.
Need to make sure you keep bleeding the system until fresh, clean fluid appears at the bleed screw. If fluid seems to be rid of bubbles, but stilll looks dirty, keep bleeding. This is because brake fluid absorbs moisture over time (don;t mean to teach you to suck eggs), therefore making it compress when the pedal is pushed.
A note on drilled discs - they can increase pad wear, obviously due to the edges of the holes acting like a grater! Don't drill then to solve a problem that shouldn't be there on standard brakes.
I'm off to plaster my skinned knuckles after doing a cam belt change on my Honda Civic!
Yep I had similar issue with my 2L 155 on STD Disk/Pads
Removed both callipers, removed bleed nipple, inverted, forced the piston back to release a massive amounts of C34p in piston reservoir. Flushed system with NEW brake fluid, replaced callipers & bleed as normal..(z style for abs cars )
I also wire brushed the callipers to remove residual rubbish. Pay special attention to the valley that holds the brake pad, this should be cleaned thoroughly. Also clean & grease the two metal rods that adjust calliper movement (the ones covered by a rubber seal)
Lot of work, I've got 4 shiny brake disks now on my 155 and neck ache
Standard brake fluid should be changed periodically as it’s hydroscopic (adsorbs water) and performance decreases with water absorption.