trykemike, I can usually keep a steady 120kph (75mph), but I use the 16t front sprocket so the engine is turning about 500 rpm less. That is with no head wind. With a head wind I can only maintain a consistent 112kph(70mph) sometimes having to shift down into 4th. there is a chart here that shows rpm vs speed:
http://www.gz250bike.com/viewtopic.php? ... c&start=90