Set your helmet down over a freshly opened box of baking soda. After it sits over night there won't be any oder. This works so well, I have gotten into the habit of putting my helmet over a box of baking soda everytime I get back from a ride. :yw1:
I called HJC customer service a few months back and they told me to use the fabric softener sheets you normally use in the dryer. Put a sheet in the helmet and put the helmet in a helmet bag. Not perfect, but it helps.