- Aug 27, 2003
My 1992 KDX 125 loses speed and appears flat in 5th and 6th gear, does anyone have an idea what the problem may be? I am considering taking the head off and pehaps decoking and new piston rings. Took it off road today around Leicestershire where I live and it performed well. On the roads it handles well but top speed is only 60mph and like I say 5th and 6th appears very flat.