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93 ATK 4Stroke Valve Stack

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My new project is a ATK 350. The suspenchion has been changed for woods. It is way to soft. I need to stiffen it up for MX riding.

Does anyone know the stock valve stack for a WP shock?

Presently:

comp.

4x40x0.2

39x0.2

36x0.25

34x.2

31x.25

30x.25

28x.3

2x26x.2

24x.3

22x.3

2x20x.2

rebon

32x.2

34x.2

2x32x.2

2x30x.2

28x.3

26x.3

24x.3

22x.3

19x.3

Explain the coil spring on the cup over the rebound stack. Against hte 30mm shim?

I have ordered 40x.25 and 34x.25 shims. Am also trying to read and understand another thread here explaining the stack and pyramid.

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Brucifer, there should be a number stamped on the end-cap/seal head of the shock. If you can get that number for me, I can get you the factory valve stack.

The spring on the top of the rebound stack is your rebound adjustment. It's basically a mid-to-hi speed adjuster. In other words, when you're in your garage and bouncing on the seat, you won't feel much (if any) change in rebound damping as you turn the adjuster. Out on the track, when the shock is able to generate enough speed, that's when you'll feel the difference. There's also a very specific way to set that system up. Let me know if you need help with it.

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Thanks RKS1 for the help

On the shock I found ATK2TPAT stamped on the body.

Also if you can, the forks have ATK2T92 on one of the top nuts.

So far the shock is the biggest problem.

Any INFO you can give is appreacated. It is hard to imagine how little the shim must deflect.

KTM-Lew, I sent and email to americandirtbike, no responce yet. $500 for a new shock.

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Ah-ha.......did ATK have a bike they dubbed the Patriot? I recall there was a company called Patriot that was involved with ATK in the early years.....my history and basic knowledge of the ATK ended when Mike Young decided he'd had enough of them!

Anyways, it's a 1992 with a Super Adjuster shock. Let me see what I can dig up. BTW, you say the shock came off a 350 4-stroke? The "2T" means it was supposed to go on a 2-stroke.

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well, whadda ya know? There WAS an ATK called the Patriot!

Here's your info:

Comp:

40x0.20

34x0.20

24x0.10

38x0.25

34x0.25

26x0.15

3-38x0.30

34x0.30

30x0.30

26x0.30

Rebound:

32x0.15 (w/flaps)

34x0.15

32x0.15

30x0.15

19x0.15

32x0.25

30x0.25

28x0.20

32x0.20

28x0.30

26x0.30

Standard Comp clicker setting #3, standard Rebound clicker setting #3.

N2 pressure: 14BAR (approx. 205psi)

Eye/Eye Length: 359.5mm

Stroke: 111.5mm

Standard spring: 8.2kg x 215mm L

Rebound adjsuter disc (the one that threads on to the rebound adjuster rod and holds the small spring in place) 1.5 turns on. In other words, turn that disc down on the spring until it just touches, then turn it 1.5 turns more, and tighten down the lock nut.

Good luck!

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Thanks RKS1 :thumbsup:

I guess I didn't order the right shims. But I will get a bottom-out-stopper. The shock didn't have anything.

I plan to try 7wt. oil.

see how it works sunday.

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This is as close as I could get it with what I have on hand.

Comp:

40x0.25

34x0.20

26x0.10

36x0.20

32x0.25

26x0.30

5-40x0.15

30x0.30

28x0.35

26x0.35

There appears to be 3 transions. I would say I am stiff,close,soft?

Rebound:

32x0.15 (w/flap)

34x0.15

32x0.15

30x0.15

19x0.15

32x0.25

30x0.25

28x0.30

26x0.30

24x0.30

22x0.30

On the floor it seems soft.

Rider sag at 3", free sag 1-1/4". The spring is old with no #. 0.480 wire.

I have a 100-165 spring that has 0.460 wire.

Try it sunday :thumbsup:

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The ride sunday went OK. NO comp or rebound damping though. Like riding a spring. My next test will look like this. YZ426F front end with the ATK 21 and brake. (the brake is GREAT) and a revalving of the shock.

comp:

3-40x0.15

34x0.20

26x0.10

40x0.15

32x0.25

26x0.30

3-40x0.25

30x0.30

28x0.30

24x0.35

rebound

32x0.15-tab

2-34x0.25

32x0.15

30x0.15

19x0.15

34x0.25

30x0.25

28x0.30

26x0.30

24x0.30

22x0.30

Rebound spring 1.5 turns

Your Thoughts :thumbsup:

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How are you assembling/bleeding the shock? The comp adjuster must be disassembled and "floated" into place...but I'm sure Richard will have the correct/better way to do it...

I bet you have something wrong on the rebound though and it's bleeding off damping in both directions...

Did you ever try calling Keith at ABD? He built those bikes back-in-the-day and still does.

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brucifer.....I don't know about that 3-stage stack........by my main concern is that you get the "tabs" of the first rebound shim covering the correct bleed holes. Double check that, just to be sure.

And Lew is correct on the comp adjuster. Does that one have the two beveled washers that face each other? If so, those need to be slightly pre-loaded against each other and that is position #1, with the sucessive positions actually pulling those washers harder against each other.

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Thanks KTM-Lew for the link to the shock. I will put that in my watch list for now. I just bought a 450 crank & piston for the bike and was trying to slow down on spending, AAHW what the heck :thumbsup:

RSK1 there should be a imbearesed smilie for me. I should have ask what are these holes in the piston, or what are the tabs for on the shim? Live and learn. :thumbsup: So I will leave the shim stack alone and cover the holes with the tabs.

I am afraid you have lost me on the beveled washers. Comp adjuster is the nob out side the shock on the N2 res?

In the shock there is a thick beveled washer that starts as a stim stop. the the comp shims, the piston, then the rebound shims with the cupped washer under the spring and nut. And the big nut holding the piston in place.

How much oil should be under the N2 piston?

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Yes, the comp adjuster is the black knob at the reservoir. If you didn't remove it, that's fine. To set it correctly, turn it (if I recall) counter-clockwise....this should make the stem thread OUT of the adjuster, but it will stop as the two beveled washers make contact. That is position #1. Maybe you didn't even remove the black knob? If you didn't, don't worry about it. It'll be fine as-is.

As a rule of thumb, the reservoir should be 10% oil and 90% nitrogen. In the WP shocks, the reservoir is usually about 100mm long. So, from completely bottomed - and when I say bottomed, I mean it's at the top of the reservoir tube when the shock is held up-right (but "bottomed" when the shock is upside-down and being filled with oil....got it?) it'll move "up" 10mm. Just remember that the reservoir must have more n2 than oil and you'll be fine.

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With the tabs over the hole there is dampening. THANKS for the help

The comp. nob has 7 positions and does not seem to unscrew. It stops hard on about 1 turn.

When I said 3 stage I was refuring to the smaller shims between 40mm and the 38mm shims. What I have read about other valve stacks I would call this stages.

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With the tabs over the hole there is dampening. THANKS for the help

The comp. nob has 7 positions and does not seem to unscrew. It stops hard on about 1 turn.

When I said 3 stage I was refuring to the smaller shims between 40mm and the 38mm shims. What I have read about other valve stacks I would call this stages.

Richard isn't saying it's NOT a 3-stage, he's saying that probably isn't the best the shock could be. I would build a 2-stage and see how it works. The adjuster knob has a set screw in the side holding it on the shaft.

I would be tempted to try a single stage? Then work a "stage" in the LS if needed.

3-40x0.25

4-40x0.15

38x.20

36x.20

34x0.20

32x0.25

30x0.30<probably change to .20 or .25>

28x0.30<probably change to .25>

24x0.35

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