pulling to the left / possibility ?
 

if one of the front forks is low on oil can this cause pulling to the left ?

Making sure that the oil in both forks are the same viscosity and level is an quick and easy fix.

Making sure that the the tires have the correct pressure (tire manufacture, not Harley's recommendations) is another quick and easy fix.

If the bad alignment has gone on long enough, the tires will need to be replaced due to uneven wear.

It is possible the the spacers were installed incorrectly during the last tire change and that is what is causing the problems now.

I don't think checking amount and viscosity of fork oil is quick and easy. If the spacers were reversed, how would the rotor fit into the caliper?

Changing the fork oil and adding new is quick and easy.

I didn't use the word "reversed" when talking about the spacers, I used the word "incorrect". That could mean that during the last tire change, the wrong spacers could have been grabbed by mistake.

To answer your question: Yes.
Check neck bearings.
Also check rear wheel alignment.

Mine was doing this as well. Thinking rear tire, then I felt stupid, I looked in my saddlebags. Most of the weight I was carrying was in my left saddlebag. Evened the weight out and no more pulling to the left. Just thought I would share that with you.

solid point.

No. Bikes only pull because of road crown or wind and then only if you remove your hands from bars. Low tires will cause them to act crazy or baddly cupped tires from running them way out of balance. Some system actually use two uneven springs rates in the forks and normal non inverted damper would still damp with only 1/2 the proper amount of oil.
Those two forks joined by the upper and lower bracket, fender brace and wheel are like one pole.