2003 rm 125 brake

Measure how long it is with a piece of wire and contact one of the companies that make brake lines to see if they have one that length with the banjos in the correct orientation. If they don't they should still be able to make one. Made exactly this mod on a number of bikes in the past.

If you want a clamp to hold the brake line on the guards, and more modern ones won't fit, rivet a 90 degree piece of aluminium to the old guard. Set it behind, to make it look less ghetto, and cover it with tape to protect the forks.

This is actually fairly easy....

You want to order an 04+ front line or one that says it is "CR Style"

I have an 07 Kx 450F front brake caliper on mine and it is direct bolt on. Let me know if you have any questions.

I used to have an 03 as well and I put a complete brake from an 08 kxf250, bolted right on.

I FELLED OVER IN THE BRAKING BUMPS AT CYCUL RANCH AND THE LEVER BRAKED WE GET A FOLDING LEVEER THEY SAY FIT ON ANY SIZE OF SUSZUKI I THINK IT WORK A GREAT IDEA

You might want to order a set of lower fork guards for an '04; it will make bolting the brake line to your slider a little easier. (Or pick up a Genuine Suzuki one, left-side only: 51511-37F60.)

What I did on an old Yamaha that had the same fork guards is remove the pinch clamp from the bottom and used it at the top. Trim the lower loop so it isn't a hook shape and drill a hole in it, then use one of the bolts from the clamp to go through it. Just use the other bolt to keep the clamp tight. You can route the brake line through the top loop and into the clamp, then around the inside of the fork slider to the caliper.