That sounds pretty much spot-on for stock displacement, Neil.

 

Yeah i think you guys will be nearer the truth, it had a 17" front and back wheels. I cant remeber how many teeth were on back sprocket but it was as small as i've seen on this type of bike. 80mph sounds scary enough for me on a klx. might see if i can find old sprocket if the scrap bins haven't been emptied at workshop.

 

I had a 14/39 sprocket combo when I hit 106. I still had a bit more to go in the rpm range too. I have a muzzy header so it definitely opened up the top end and gives you more room to play.

My girls new Ninja 250 feels rock solid at that speed. But just as buzzy.

I would say 85mph true is about max for this bike at 250cc. Maybe downhill with some wind you could break 90 mph. Could be dangerous as that's nearing max speed on some knobbies. I would try it on street wheels though.

 

Found old spockets as am about to sell the old KLX and think it might sell better as a Supermoto, front was a 14 and rear a 37! Thanks for all the help and advice I've gained off this site, time for something new!
All the Best
Cheers
Pete