KDXRIDER.NET

My recently acquired scooter has issues.
Generally neglected, once loved as shown by the Pro Action fork sticker, fresh top end with some engine builders logo engraved in it, PC Works pipe, V-Force carbon reeds, big gas tank, spare plastic, etc. It has *ENGINE* like nobody's business... but everything else needs love.
The forks mainly... I can clean up the rest of the ignorance... how in the world could someone screw up forks so bad? Of the 40 bikes I've owned over my years, the suspension is ghastly on this piece. It is literally unrideable, has zero traction at either end. Never had a USD equipped scooter, so they're kinda strange to me. No leaks, tubes are clean, ding free, straight... but have about 6" of sticky travel even with my portly 265#. Have to pull up on the bars to get the top 1" travel sitting static. I pulled them out of the triples, popped the top caps, and found the clean green oil filled to the top of the compressed lower legs. Hmmm, I said, found it on the first shot! Blurped the level down to 5" from the top, reassembled, and... nothing.
Same rock hard POS.

Emailed Pro Action to no avail. The setup sticker is unfortunately gone. I understand they're in business to sell jobs, but these have zero compliance and I assume they have actually been blessed by their company at one point (unless you can buy vintage PA stickers outright). Just looking for a little guidance, as I don't mind getting dirty. Both tubes, as "tested" individually off the bike, feel the same to me.
Valving? Could someone have screwed up the shims? Does something "blow out" in these USD units that I've never heard about? I see rebuild kits available, but kinda find it hard to believe that bushings would get this bad especially if they've been "done" at some point in their life.
This can't be rocket science... open for suggestions...

THANKS IN ADVANCE!
Pete

The bushings can cause a huge amount of stiction, my RM forks actually have "special" bushings to limit the stiction that the factory ones cause. And of course, you need to know the spring rate and check out the valving. Yes, valving can be screwed up that bad.....Builders can, do and will screw up gold valves, so check the valving....
Basically your going to have to take them apart. Another option is to find a tuner in your area and let him deal with them.

Thank you.
Is there a site, diagram, youtube or somewhere to guide me in the right direction?
What does a bad bushing look like, as in do they usually wear the same?
I have no issue pulling them apart myself, but honestly wouldn't know side A from side B regarding correct order of the guts.
Is all of the valving in the bottom?

Unfortunately I would have no clue about the spring rate. They couldn't possibly manufacture a spring this stiff to overcome my current weight . My 14 year old tried to ride it and it had so much headshake at the top of 2nd on a relatively smooth field that he handed it back after 5 minutes and said "no thanks, this thing's uncomfortable".
Wasn't quite the response I was expecting after climbing off of a 9hp DRZ125 that's way too small for his rapidly growing frame.

How about just pulling out the spring and then sliding the fork in/out to see if there is binding?

Did that when apart the first time, really didn't notice anything out of the ordinary.

Then again, I had it in my mind that the overfill was causing hydrolock...

Anything is possible at this point, will recheck when I pull them out again.

Could be one issue or several acting together...here's the progression I'd use:

Make sure the forks aren't binding. The lower triple bolts should barely be tightened... just enough to be kept in place - a lot of people over-tighten those and binding results.
Back off the front axle pinch bolts and push the front end down several times while holding the brake on - the idea is to make sure the bottom of the forks are the correct distance apart...and that can only happen if the forks are worked freely on a freed axle BEFORE the axle pinch bolts are tightened.
The next thing is a hydraulic issue....
Pull the forks, dump the oil, and put 2.5 wt oil in at 120 mm. (no springs: 120 mm from top fully collapsed). (Amsoil light five is about 2.5 wt). I've setup a bunch of YZ forks and for off-road the 2.5 wt works great, and even better with a compression valve revalve (but just changing the oil makes a huge difference to start).
Finally, the spring rate itself may be too stiff.

Bushings are teflon coated, when you look at them, you will know whether or not they are good. They are not expensive and if your tearing the forks apart, you might as well replace them. Best source for schematic is the repair manual for that bike.
It could be any number of things....so best bet is to get a clean work space, where you can leave a fork un-assembled (in case you need to leave them apart for more than an hour) and get one of them apart and start looking for broken/worn/bent parts.
Could be as simple as the PO took them apart and managed to put them back together wrong, but that could also damage stuff.

MotoArts wrote:What does a bad bushing look like, as in do they usually wear the same?.

Here is a new vs. worn bushing.

If you are 265# and only using half the travel, the only way your springs could be too stiff is if they were custom made. Those things would have to be so beefy that I think it would be obvious just looking at them.

I made a cheap little spring rate tester a while ago. The .48 springs compressed ~42mm with 45 pounds on them. You could try to rig up something similar to get a ballpark for what you have in there.

spring rate tester

I would bet that something is bound up, damaged or installed incorrectly. But as others have already mentioned, only one way to figure that out.

Thanks for the input, guys.
I'll report back after I get 'em apart.