Suspension swap

It is, you can swap the triples right on to the older kx250 frame. Very very worth it

It's been awhile since I had an 01 but I believe the subframe bolts are in line with the top shock bolt which means on the newer shocks the resevoir tilting up hits the subframe. I believe to run newer triple trees you need to add steering stops to the frame. I have a 98 kx250 with 07 kx450f forks and they fit the stock triple. 01 forks are different size than 98.

I have a set of 06-08 kx250f showa forks if interested. $150 plus shipping

Would anyone know about putting a 2011kx250f shock on a 2003 kx125 thanks

I know the 07 kx250f rear shock physically fits the 03 kx250 on the top mount. Bottom clevis is a fair amount longer which makes shock longer.

If you put the 2002 kx250 triples on, some YZ kyb sss will bolt right up.
You'll then have to change the brake and wheel...