I just changed the oil on my Wee for winter storage last week, and also had a ticking from the rear cylinder when I started it up. Check the oil level, it was a little little low as some was absorbed by filter, added oil, started bike and ticking was gone. I know some people check the oil with the bike on the centerstand, this gives a false reading since the oil flows to the front of the engine and appears higher in the sight glass than it really is.
2009 Wee Strom ABS (current)
1987 Harley Low Rider Sport (current)
2009 Aprilia Mana 850, 2006 SV650, 1984 Yamaha Virago 1000 (all sold)
Silver Strom Club Member #11
Wee Farkles: SWMotech Centerstand, Framesliders, Forkbrace, Elka Shock, Aprilia mirrors, Fenda Extenda, Suzuki Handguards, Madstad with Moose Adventure Shield +4'', Russell Day Long Seat, Givi XS308 Tankbag.