top layer prints very bad

The top layer prints awfully. What could be the cause?
Bottom and Perimeter print more or less well.
When I print x/y narrow parts, the infill seems to be too much. But this looks to be far to few material.
Is the extruder losing steps? is there any other problem in PLA feed?
(I already own 4 hobbed bolts. The best one is in use)

I tried to reduce top layer speed from 30 mm/s (photo) to 20 mm/s, which did not seem to help much.

I don't have that much experience with PLA but couple of things if you have a heated bed and your printing real thin or what would be short objects. Try to print it without turning heated bed on there are many solutions to get it to stick on a cold bed. Second small parts even if you don't need them print more than one this gives the plastic time enough to cool between layers. With PLA a fan directed blowing on the part is pretty much always needed

Edited 1 time(s). Last edit at 05/24/2014 09:18AM by cnc dick.

It looks like you are printing too hot.. both heatbed and hotend. You may want to try increasing your extrusion mutlipler a couple %. How many layers do you have on you top layer? When I have my infill set very low my tops looke like that until the third layer, then it smooths out. Slic3r will allow you to change settings for solid layers, and more. You may want to try and play with those settings also in expert mode.

Are the dimensions of your model appropriate for your layer height? I've seen this before when trying to print, for example, a 2.5mm high model using 0.2mm layer heights. The first 12 layers print at 0.2mm just fine, but the software will under-extrude the last layer in order to get the necessary 0.1mm height. If you can change your layer height so that it's an even multiple of your model height, that may give you better results. Good Luck!