Upside down fork question...

[Sci85]

Haha, I like that guess.

Sometimes people would use two different spring rates to achieve a certain feel that two of the same could not. Rarely do you see that anymore.

I would check the bushings in forks that old. They are designed to wear.

And yeah, 2004 is old from a KTM suspension perspective. They really didnt start to get it right until the last 2-3 yrs, and really started to get it just within the 2012,2013 models. However, in the right handseven WP forks can be made to handle well. The kicker is finding a company that has that know how. Not nearly as many around as those that know KYB and Showa and it truly is a fine art.

Good luck!

[Sci85]

Oh, and yeah, theYZF handles great. Yamaha uses KYB SSS suspenstion which is some of the best from the factory. Unless you weigh a lot more or less than the magical 165lb rider, all you need usually are clicker adjustments to get them good for your skill level and terrain. If you are 200lbs or 145 you would need different spring rates but they are super simple to change. KYB SSS or even the older AOSS (speed sensitive suspension/air oil separate suspension) are awesome.

[tkent02]

Haha, I like that guess.

Sometimes people would use two different spring rates to achieve a certain feel that two of the same could not. Rarely do you see that anymore.

I would check the bushings in forks that old. They are designed to wear.

And yeah, 2004 is old from a KTM suspension perspective. They really didnt start to get it right until the last 2-3 yrs, and really started to get it just within the 2012,2013 models. However, in the right handseven WP forks can be made to handle well. The kicker is finding a company that has that know how. Not nearly as many around as those that know KYB and Showa and it truly is a fine art.

Good luck!

I may well end up getting a newer one, but not just yet. Like I said, I have ridden older KTMs that rode very well in the rocks. Yep, the bushings are new, as are the seals. The old ones weren't very worn. I have a guy here who is highly recommended by everyone around here, does a lot of KTMs, but I need to get the thing to not bind up first. I took the springs and cartridges out, noticed one tube slid in and out a lot easier than the other. Like three times as hard to move. I swapped the inner and outers left to right and now they both slide about the same, not like a trombone slide but a lot better than it was.

Again, WTF?

Next I'm going to install them in the triple clamps, install the axle, torque everything down without any springs. Then I can see if they bind up easier. Theoretically, they should still slide just as easy.

[tkent02]

Next I'm going to install them in the triple clamps, install the axle, torque everything down without any springs. Then I can see if they bind up easier. Theoretically, they should still slide just as easy.

All slides just as easily until the axle goes in, torque everything down and then it gets sticky. Went for a little ride, there's a road here with broken pavement, a good suspension tester. The brake line goes over the headlight/number plate thing, you can hold it in your left hand with the hand resting on the number plate and feel the forks move. It moves up or down with brakes or throttle, but hitting the bumps, the forks do not move at all, not one iota. Stuck hard. Like a hard tail, but it's a hard nose. Sucks.

Put the parts bike forks back on. They work OK, just undersprung and I have no idea what's in there for oil, but thay are not stuck. Then I dropped the other ones off with the suspension guy. He knows his stuff, he rattled off a bunch of things to check that I never would have thought of, and couldn't check anyway. We'll see what he comes up with.

And in other news, the Suzuki with the new forks and springs is riding better than it ever has before.

[tkent02]

OK, got it back, he did some things, used better bushings, shimmed them into the forks.
He also found the lower triple clamp was not bored right, or was slightly bent. The fork holes are not straight. The hole in the lower isn't aimed at the hole in the upper, if the forks were 100' long they would come together. But he didn't think that was my problem.
Slides nice and smooth off the bike, so I took it for a ride....
Better, much much better but still not right. It's moving on the bumps now but still a lot of stiction. Not as smooth as either of the Suzukis. In fact it's got more stiction than any of the bikes in the garage, new or old, street ot dirt. But at least I can ride it now.

Think it's time to go pound it on some rocks and see if it gets any better.

[08rangerdan]

I had a beauty of a bike. Was a 91 cr250r.. Restored. Was a monster to handle with the horrible forks up front.. Just no adjustability!! Except rebound.

All i can say is that any motocross suspension should be tested at higher speeds. Oil weights are a big factor, and make small adjustments! At low speeds adjustments wont be hardley noticeable. You gotta make that valving work.

If you are just booting around slow speed, id be running a heavy weight oil and firm setting all round. You dont want your wheel moving much, just limits its bite at slower speeds. And remember the rear shock setup directly affects the front suspension predictability. Make sure the rear is set for your weight.

[tkent02]

I had a beauty of a bike. Was a 91 cr250r.. Restored. Was a monster to handle with the horrible forks up front.. Just no adjustability!! Except rebound.

All i can say is that any motocross suspension should be tested at higher speeds. Oil weights are a big factor, and make small adjustments! At low speeds adjustments wont be hardley noticeable. You gotta make that valving work.

If you are just booting around slow speed, id be running a heavy weight oil and firm setting all round. You dont want your wheel moving much, just limits its bite at slower speeds. And remember the rear shock setup directly affects the front suspension predictability. Make sure the rear is set for your weight.

No it's different here. Nothing but rocks. Big rocks, little rocks, wet rocks and dry rocks, loose rocks and tight rocks. We have round rocks and sharp rocks too. There are some flat rocks, but usually they are standing on end. Bite isn't a problem, pain is. I ride as fast as the rocks allow, and no faster as falling onto rocks at speed hurts. Especially the big sharp ones. Doing that ten miles from a road or another person would be a bad thing. I want my wheel moving as much as it needs to for the big rocks, and it does. It actually feels pretty good on the big rocks, going fast it's really good. My problem is the little rocks. They hurt if the suspension doesn't move. It's not a damping thing, it a stiction thing. Damping does nothing if the forks don't move.
This isn't a motocross suspension, maybe it used to be but no more. It's a rock suspension.
However the bike works at higher speed and smoother places I can deal with, but it must have a smooth ride on rocks or I can't ride it.

Oh, we have some roots, and logs, but not as many as rocks.
Also we have holes, where a tight rock used to be, before it turned into a loose rock.

[Sci85]

For rocky and woodsy type terrain you need to have the high speed shim stack opened up. And you need to have the proper spring rates as well. For motocross, we usually go up in spring rate to keep the forks riding high and control the movement via the shim stacks. For woods however, if I'm looking for a plush ride, there are two schools of thought. One is to again use stiffer springs and control the movement via the stacks. The other, more old school method, is to drop the spring rates and allow the forks to settle under the bikes weight about 1/2". I prefer the old school method if I know I will not be doing any jumping and will be hitting a lot of rocks and square edged type obstacles.

Stiction is going to be higher on the UPD forks than any RSU forks by design. Not much you can do about it.

It takes a lot of trial and error to dial in a set of forks but it does pay off. Good luck!

[tkent02]

For rocky and woodsy type terrain you need to have the high speed shim stack opened up. And you need to have the proper spring rates as well. For motocross, we usually go up in spring rate to keep the forks riding high and control the movement via the shim stacks. For woods however, if I'm looking for a plush ride, there are two schools of thought. One is to again use stiffer springs and control the movement via the stacks. The other, more old school method, is to drop the spring rates and allow the forks to settle under the bikes weight about 1/2". I prefer the old school method if I know I will not be doing any jumping and will be hitting a lot of rocks and square edged type obstacles.

Stiction is going to be higher on the UPD forks than any RSU forks by design. Not much you can do about it.

It takes a lot of trial and error to dial in a set of forks but it does pay off. Good luck!

Springs are right, sag is right.
Well my other bike with upside down forks rides smooth as can be in rocks. So do other bikes identical to mine that I have ridden. Shim stacks don't do much if the damned things aren't moving. Just rode it an hour on some dirt roads, nothing too rocky. This thing sucks. Worse than all the bikes in the garage, worse than the '84 XT 250 with the rusted original shock, far worse than my wife's DR 200, worse than the 1978 TS 250 with original crap suspension, worse than a stock 1979 GS 750 on a dirt road.

I think I'll part it out, just because I'm sick of looking at it.

[tkent02]

Actually I won't prt it out, I like everything else about it. It's light, powerful, great brakes, everything but the fork works perfectly.

Maybe I should keep an eye out for those '98 RM forks. I wonder if the triples would fit right in...

[Sci85]

I know lots of folks swap out the WP for showa's or kyb units. I doubt the triples would fit. kTM uses odd ball sizes for just about everything...

[tkent02]

Ya know, there's still something wrong. I don't have to swap anything, just need to fix these. I have ridden other bikes just like mine, identical bikes, with the same forks and shocks. Also ridden quite a few other KTMs, different sizes and year models. These bikes have all given a very smooth nice ride. Comfortable, even in rocks. Plush. They were not all set up for my weight, but they were pretty darned nice anyway. And mine is a piece of crap.
Just need to find out what is making these forks bind up...

What else can it be?

The tubes are straight, all four of them. The axle is straight.

WTF?

[Sci85]

Well, you said that they are ok on the big bumps but stiff on the squared edged, smaller bumps and rocks correct? If that's the case I doubt they are bent. So I would bet that either the damper rod is clogged with something or the compression adjuster is clogged. Did you disassemble and clean everything out good with compressed air? The compression adjuster will require some special tools to disassemble. Again, an expert will be required.

Someone may have also had them modified for SX or MX in which case they would exhibit this behavior. They could also have had the stock springs replaced for some very stiff ones for a heavier rider. If you can't compress the fork by hand an inch or so, then I would suspect the springs have been changed out for someone much heavier than you.

Good luck!

[tkent02]

Well, you said that they are ok on the big bumps but stiff on the squared edged, smaller bumps and rocks correct? If that's the case I doubt they are bent. So I would bet that either the damper rod is clogged with something or the compression adjuster is clogged. Did you disassemble and clean everything out good with compressed air? The compression adjuster will require some special tools to disassemble. Again, an expert will be required.

Someone may have also had them modified for SX or MX in which case they would exhibit this behavior. They could also have had the stock springs replaced for some very stiff ones for a heavier rider. If you can't compress the fork by hand an inch or so, then I would suspect the springs have been changed out for someone much heavier than you.

Good luck!

Yes, big rocks and landing off little jumps and such, very nice. Just sticks to the ground. Also with the front wheel in the air, very nice. The rear wheel just sticks to the ground and digs in. But unfortunately, I can't wheelie forever.
For every big rock there are a hundred little ones, they are bone jarring.

I put in the correct springs for my weight. I can compress them by hand once the fork moves. It is stuck. It's not a damping thing, it's a stuck fork thing.

If I hold the front brake and push hard, I can compress the forks about five to six inches, just about like my DR 350, which is also sprung for my weight. The difference is the DR will move a little if I push about an ounce, the EXC I have to lean into it to get it to move at all. Stuck. The other difference is the DR rides over rocks very well, smooth and comfy. Nothing is bent, all four of the tubes are straight. Measured with a dial indicator while rotating in a truing stand.

The suspension expert took the compression adjusters apart, made some valving changes, didn't mention anything wrong in there. I didn't take them apart, just took the whole cartridge out and brought it to him, but everything I saw looked clean as a whistle inside. The oil was clean, not perfectly clear green but pretty darned good.
I have never seen stuck forks before that didn't have something bent or extremely worn out.

I wish someone with your experience were here to look at this with me.

[Sci85]

Yeah, me too tkent02. Something is certainly f'd up. I'm thinking something is not assembled properly or possibly an incorrect ID seal?

If you take the fork out of the triple clamp, can you move it by hand then? If so, remove the spring, put the cap back on, and see how easy it is to compress by hand.

Do these forks have preload adjusters?