I also have an '09 Stella, but have not had any problems like that because it does not rain in my state, at least not in the part of it where I live. Ask on stellaspeed.com. Something somewhere is grounding out when it gets wet.
2002 Vulcan 750 (engine out, slowly being disassembled) 2013 Royal Enfield B5
2001 XT225, 2009 Genuine Stella
2012 Zuma 125, 1980 Puch moped