ASK THE MXPERTS: HOW TO SET-UP THE LAST PDS KTM 450SXF

Do you remember PDS suspension? It was on the KTM 450SXF until 2011.

HOW TO SET-UP THE THE LAST PDS KTM 450SXF

Dear MXA,

I own a 2010 KTM 450SXF. It is the last KTM motocross model with single-sided PDS rear suspension. I’ve tried everything to get the rear suspension to work. Help?

The 2010 KTM 450SXF was a very good bike—and its single-side, no-link rear suspension could be made to work (and still comes on some of KTM’s offroad models in 2019). The 2010 450SXF was the first of the five-speed transmission engines after a couple years of four-speeds. It was the first year that KTM switched to 22mm offset on the forks. The KTM rear shock was 4mm shorter than in 2009. The shorter shock lowered the rear of the bike by 10mm (without affecting rear wheel travel). That 10mm number is significant when mated to the lower frame, ride height, engine location and swingarm pivot. KTM left the head tube in the same place in the frame jig and then welded the frame 10mm lower on the head tube. This simple engineering fix resulted in a lower center of gravity, lower crankshaft height, leveler swingarm and lower seat height. All good stuff, especially when combined with the shorter WP shock. The WP PDS shock got completely new damping settings. In the past, KTM required the low-speed compression and rebound clickers to be turned out 20 or more clicks. For 2010, KTM changed the taper profile of the adjuster needles to bring the clicker numbers down to ballpark settings of 12 clicks out. Low-speed damping was increased, while high-speed damping remained about the same.We set the race sag at 105mm, the high-speed compression on 1-1/4 turns out, the low-speed compression on 12 clicks out and the rebound on 12 clicks out. The real problem is the shock spring, thus the fix for the 2010 KTM 450SXF’s rear suspension is a different shock spring. KTM always does a weird dance with its PDS spring rates. PDS suspension started out with a 6.6 kg/mm spring. MXA ran a 6.9. The next year, KTM installed a 6.9 on the production bikes and MXA ran a 7.2. The 2010 KTM had a 7.2 kg/mm spring, but we ran a 7.6. What’s the deal? It was obvious that KTM was willing to change the spring on its new models, but someone at the WP factory sabotaged the spring changes by lightening the damping to keep the bike exactly where it was with the lighter spring. Our advice for 2010 KTM 450SXF owners is to run a 7.6 spring on your stock WP shock (especially if you are over 175 pounds).

MXA’S 2010 KTM 450SXF SHOCK SETTINGS
Spring rate: 7.6 kg/mm (7.2 kg/mm stock)
Race sag: 105mm
Hi-compression: 1-1/4 turn out
Lo-compression: 12 clicks
Rebound: 12 clicks

 

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