KTM LC4 620/640 & 625 SXC Suspension Information and Upgrades

These bikes have given KTM endless enduro wins worldwide. They also make a fantastic adventure bike.

The KTM 620, 640 and 625 SXC are derivatives of the very popular LC4 line, having proved it’s reliability and competitiveness in almost 20 years of Australian Safari and world rally raid competition. Technically there are some differences between the Adventure and the SXC, but the goals for suspension performance are the same for any safari machine.

  • The fuel loads will vary greatly throughout the competition day, 30-40kg variance in weight is quite normal.
  • Rider fatigue is a big factor, so the suspension must not contribute towards fatigue. Soreness in the hands, wrists and forearms is something no rider wants. This requires suppleness in the initial suspension travel. This will also help look after the bike, lessening fatigue to the metal parts on the machine.
  • The suspension also needs to save the rider from those “oh shit” moments, when you've ignored a caution on the course late in the day when tired and come into a 2m wide 1m deep rain washout at 140km/h. This requires motocross-like settings that are too hard on the body for long days.

It often unfolds that a good suspension set-up for safari also translates to a good setting for adventure riders, allowing longer days in the seat, with less risks and greater control.​

KTM LC4 620/640 & 625 SXC Forks


The standard settings are compromised as the manufacturer has to design a package that will suit everyone, whereas we can be more specific. The fork springs are replaced for some heavier 0.50kg/mm (depending on rider weight) 19-190 Series Fork Springs. Why go heavier? They will support the heavier fuel loads, and with the valving changes will still feel plusher than stock.

We also use a high flow compression base valve of our own design, and these have proved very popular in the WP fork to alleviate the harsh feel on tree roots, loose rocks and corrugations. The rebound, mid-speed and base compression valving is then replaced with a setting that Teknik have developed for the Safari. Forks are filled with 5wt fluid, 140mm from the top.

KTM LC4 620/640 & 625 SXC Shock


The LC4 retains a linkage system, unlike the PDS rear shock on most other KTM models. It has proven to be very reliable, but needs some attention for safari type events. There is also an option of removing some of the travel limiting spacers for increased ride height.

We have found the stock WP rear shock springs loose their free length over time, and you will need to keep readjusting the sag. Because of this, and a need to raise the rate, we replace the stock 63Nm WP suspension spring with a heavier 20-075 Series Shock Spring.

The valving also comes under attention, with a new setting for safari. Plush at the beginning, firm enough to carry the load, but firming up towards the end of the stroke. We use high quality oil with good resistance to heat related fade, Maxima medium.