SKF Seals and another fork rebuild

The new SKF fork seals came in a couple of days ago, been trying to clear some time to get them installed and get the bike back together. These seals are supposed to be the hot setup for 48mm WP forks, as the stiction from stock KTM seals, as well as many aftermarket seals like the pure crap All Balls.Moose.MSR seals on there now, is well known.

Upon disassembly of the forks, I checked the upper and lower bushings. Both looked good, and really as though they may have recently been replaced by the previous owner. Cool. I also took the opportunity to do a little more work to the compression and mid-valve shim stacks (my mods are based on the ’07 Trail Tricks stack as found in the ktmtalk.com forums). Gave everything a final cleaning and inspection and started reassembly.

One tool I sprung for was an actual purpose-built seal driver (instead of half-assing it with an improvised tool made out of PVC). I bought the Cycle Gear house brand ‘universal’ seal driver that’s supposed to be good for forks from 30-something to 50mm. While it did work, I found it to be awkward, as the two halves did not mate up properly on the 48mm fork. Also, the part that actually contacts the seal doesn’t look like it’ll hold up for the long haul. If you can afford it, I would skip the ‘universal’ route and spend your money on the correct sized Motion Pro driver.

Anyway, reassembled with the new seals and dust wiper, and just like in the video, the improvement was dramatic. I filled each leg to 140mm with Mobil1 synthetic ATF, put the front wheel back on, lowered the bike back on the ground and gave the forks a push. Man, they were like a new, different, better set of forks. Where before they were jerky and stiff, they were now buttery smooth and supple. If they perform on the trail like they seem to promise here in my garage, we’re back in business. I hope so, getting tired of pulling these forks apart (have I said that already??).

Fork Re-Valve and Top End Time

Pulled the forks apart and reshuffled the compression shim stack in an effort to make the forks more compliant over roots and doll-head rocks. Also checked the compression – not that I thought anything was wrong, but just out of curiosity – and it was w-a-y down. Pulled the cylinder/piston and started measuring. Piston and rings are both shot, cylinder is worn pretty heavily but can probably take an oversize piston. Parts on order…

Can’t believe it ran as well as it did, but maybe this’ll explain the hard starting.

-B

Parts are in. Woo-hoo!

Parts are in, lots of work to do. Placed another order for the stuff I missed the first time around. Reinstalled the stock fork and shock springs in the meantime – the previous owner was heavier than me and had this thing sprung a bit too stiff for even my pizza-and-beer physique. These springs are, if anything, now a little too soft, but I’m working hard to lose some weight by the time of the first race; if I hit my target, they’ll be perfect.

-B