Top speed of KTM 250 SX

[ndejesu]

I have a 2003 KTM 250 SX and it seems to run out of speed in 5th around 50 miles an hr (I don't have a speedo, but it seems not too fast). The engine has good power, but the gearing might be the reason. It has a 13 tooth front sprocket and 50 tooth rear sproket. Does anyone know if this gearing attributes the lower top speed?

[bajadog]

Your bike being an SX model is really set up for being quick off
the line on an MX track. It's not an open terrain off road bike.

If you go up one tooth in front or down teeth in back it will
increase top end, but also make it less fast off the line, and
not as able in single track riding.

What do you use your bike for?

[ndejesu]

I am going to use the bike for MX, so I want it fast off the line. Right now I'm running across an open field and get into 5th rather quickly and run out of RPM (top end speed). First gear is really not very useful, except if I need to go around a really tight turn (almost stop).

[bajadog]

I'd recommend trying a smaller rear sprocket by a few teeth,
adding an extra tooth in the front is VERY dramatic.

Check out this gearing calculator, just fill in the blanks
and you can see what tooth size changes will affect RPM.

http://www.gearingcommander.com/