I had to use da'Google machine to look up "Harken Hoister" to figure out what one was.  I take it you've got the system with blocks and a couple of loop straps that lifts your kayak up towards a garage ceiling.  Looks like a nifty device.  Here's what I'd check:  Is your system still rigged with the original line?  Any twisted/3-strand type line would be especially prone to twists and kings and fouling when running through blocks.  Check that you're using some sort of a braided or double braided line.  Even if you find you do have a braided line, your simplest solution might be to read up in a sailing catalog to choose a new line to re-rig your system.  You'll find a number of types/brands that tout special anti-twist/kink properties.  You might pay a little bit extra for quality line to be used in this mundane application, but if it fixes the frustration of a fouled up lifting system it might be worth it.

just a note to echo bubblehead's note.  and he points out everything i would have mentioned.

i have two of these systems that i use regularly and have not had a problem.  i use a braided line (not twisted) and no twisting problem.

fwiw, i am careful to make sure my line is not twisted when i work the system (i am a former sailor so experienced handling lines)  but it does not, at least for me, seem to require any particular care.

howard   

���What kind of line? A double header Dacron will be more expensive but not twist up.

���Double braided Dacron........darn spell check.

   "when you coil a line it wants to twist"

The converse is also true: if you don't coil a rope, you won't be adding unnecessary twists. So if your system uses a lot of line, just feed it into a rope bag or a bucket without coiling.

By the way, I'm coming at this with a background in high-angle rope rescue. We frequently work with very long ropes and always store them uncoiled in rope bags. Rescue ropes are kermantle ropes (hence braided), but they will certainly twist if coiled.

You were asking if running the line through blocks adds twist. I don't believe it does so (but I may be worng). My comment above suggested that the problem might be related to how you handle the line when it is stored. Ignore if you don't coil the line.