Our TTR 125 has a drum brake front end. We want a disk brake front end. The best way to change out a front end is to replace everything including the triple clamps. The steering stem and bearing sizes are always close. Press out the stem, a little lathe work, make a spacer and presto.
The next step is to shorten the forks because these are 4 inches longer than the stock forks and to change the spring rate and damping. Lindemann Engineering will handle that bit.