Hi, nice bike. My 660 struggles at quarter throttle. I have a k&n filter, and dynojet kit installed. Air mixture screw 2.5 turns. I did try it at 3 no difference. Any ideas?
I just had same problem with mine. Turned out the contact points on the gear position sensor were bad. Gave a light scuff with fine grit paper to expose fresh metal and it's right as rain. Hope this helps