I've been using the Motorex helmet care sprayer and a skull cap practically every time I go out, but even then the helmets get stinko after a while. I couldn't take it any more and washed three of the most offensive ones. The Shoei flip-up was the worst because that's my commuter helmet. I had to let it sit for about almost an hour in the deodorizer water.
First step is to wash them in water mixed with bacteria killer mix (I have it for my scuba gears). Poured water in a 15-gallon trash can enough to thoroughly sink the helmets, mixed in the bacteria killer and tried to squeeze the foam inserts, getting some of the nasty gunks off. I did that to three helmets.
Second step is to put them in another 15-gallon trash can mixed with the stink killer mix. The Arais weren't too bad, I left them in for about ten minutes each, but the Shoei was so stinky that I had to leave it in for about nearly an hour.
Shopping carts make for great helmet holder while they're being drained.
http://www.webbikeworld.com/r3/helme...elmet-care.htm
http://sinkthestink.com/
