Getting good ventilation in the garage will help a lot, find a side on the garage that gets the prevailing wind and put closable vents (you dont want the draft while your in there working) in that side and at the opposite side of the garage too, buy this stuff-its 100 times better than WD40 http://cgi.ebay.co.uk/ACF-50-ACF50-ANTI-CORROSION-PROTECTION-SPRAY-MOTORCYCLE-/130445771290?pt=UK_Motorcycle_Parts&hash=item1e5f2c821a, and drape an old wool blanket over the bike too, above all try to keep up with polishing the chrome, if those tiny rust pores turn into blisters then its game over
HTH