Hi,of course its a rideable bike,lol,its only gonna go as fast as you twist that throttle round the handlebar!!!!,and by the way,if you can reach forward and grab the throttle cable between your teeth,and twist your head sideways,it will go even faster!!!!
KX500's are great fun if you weigh more than 200kg,and have arms like tree trunks,and can maintain a constant heartbeat of 300-350 beats per minute.
I used to race 250 KX's years ago,then I was offered a ride on a 500.Totally different bike.pin the throttle right back in 2nd,3rd and 4th was like trying to steer a rabid pig by the ears into a trailer ready for slaughter.such fun,such excitement,SUCH FEAR.
there are plenty of people on this forum,who will be only too happy to help you out,me included.
good luck.
