This 14 tooth sprocket is the only one out there so far that actually fits the 390 Adventure. This replaces the 15 tooth stock sprocket and changes your gear ratio from 3:1 to 3.21 :1.  This makes for much better acceleration and the bike now pulls through the flat spot between 4-6000 rpm.  It still goes 70 mph at 6000 rpm in 6th gear

14 tooth front sprocket for 390 Adventure