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i thought $100 was a great price. but i sell time primarily, and i know how long it takes to make even simple stuff, and that the time it takes to make something might to 10% or less of the time you originally invested to make the first one.

generally adjuster needles are much sharper on the end, which gives a much finer progression per adjustment increment. like a carb mixture screw.
 

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Discussion Starter #42
Yep, I agree with you 100%. I knew I was in unexplored territory, but not this far.

Like you said, it's a great deal. I should emphasize that part. :)
 

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Discussion Starter #43
More good news.

The "fixed-compression adjustment" bottom bolts came in, seem to fit great. (See photo.) Could poke a hole with a 1/16" drill bit and be done with it! 748 lowers with adjusters would be drop-in too.

So lots of options...

Still waiting to hear back from Rick at Cogent Dynamics regarding the fully-adjustable bolts. They should be out of production soon.
 

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Shim Restackor might be useful here. It's a suspension dynamics simulator. You can simulate compression and rebound behavior in forks and shocks. It goes quite deep!

You can simulate the damping of different valves and shim stacks and compare, and also simulate the effect of different oil viscosity etc. etc. - almost anything you can think of.

It can seem daunting to learn, but it's actually not that complicated. And the info on the site is very interesting imo ...

Here's a link: Shim ReStackor, Finally software to tune a shim stack

Good luck with the project!

(P.s., I'm not affiliated with Shim Restackor. I like to lurk here - have wanted a Sport 1000 for years - and thought I'd add something to the discussion from the dirt bike side of things :) ...)
 

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Discussion Starter #45 (Edited)
Any idea how much Evolution would charge for this mod start to finish?
$50 to do the cartridges.
He said drop-ship him the GSXR forks, he will strip and do the mods, then mail the cartridges back to you -- for drop-in replacement.

I visited Robert at Evolution Motorcycles today and asked for you.

He said he could also order the oil, seals, springs, etc so it's a ready to go kit.
Maybe even reshim/revalve, or reannodize the caps to match. Not sure how much more it'd be.
(He told me oven cleaner [Easy Off yellow can] works too, but mucks up the protective layer.)


If you are really uncomfortable opening the forks, i suppose you could ship both sets... then he could reannodize everything any colour you want. (I did gold tubes/cap with black accents.)

This is for (Option #3) "fixed compression adjust". You might need to have him shorten the catridge 5mm, or raise the forks 5mm in the triples yourself.

If you want (Option #4) "adjustable compression", he'd need Cogent's special adjuster screw... but said he thinks with this setup compression adjust isn't necessary if he drills the holes correctly/you're not tracking the bike.
 

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Discussion Starter #47 (Edited)
How to disassemble the compression stack
For reshim, revalve, etc.

Pictorial guide, will type up later.

Do not fully remove the hollow screw until you are over a clean work area!
The clamp shim (very bottom one) has a tendency to stick to the holder... you do not want to drop any of these shims, or get them out-of-order!

(Unless you have a template, provided below...)
 

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Discussion Starter #48 (Edited)
GSXR compression shim stack setup with dimensions

The GSXR stack uses seventeen (!!) shims in its compression stack, mostly (very, very fine) .1mm of varying diameters.
These shims flex downward when hydraulic fluid is forced through the valve holes.

The stack holder has a "shoulder" hole mentioned in Torbjorn's "Showa Blues". I included a pic of it.​

I'm not going to assume anything about more complicated = better... but this stack design looks like it came straight off a race bike.
Compare that to the 748 3-way Showa below...
 

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Discussion Starter #49 (Edited)
748 compression shim stack setup with dimensions
.... and this is the stack from a 748 with the supposedly "updated/good" Ducati compression valve.

It uses nine shims, the majority of which are not tapered and are 50% coarser/thicker than the GSXR. The clamp shims are incredibly crude as well, as is the holder.
It is impossible to keep the stack axially centered with this design, especially with that 2.5mm thick standoff at the bottom.​

Once again, I am astonished at how many corners Ducati cut in a $16,000 Superbike.*
It's like they skimped on everything that was out-of-sight. (*1990-2009 "restructuring" era)

On the upside, it means this mod will be cheaper, but give better results than, our current gold :)rolleyes:) standard of 3-way TiN Showas from a S4RS!

There are multiple things I mean by that: you see that spacer? It controls the bottom out / "how many clicks of adjustability" you get out of the adjuster screw and how load is distributed on the foot of the fork.

It's plain as day they made the cartridge, realized they messed up the design (not enough adjustability /11 clicks open max), then went back and added the spacer to try to salvage it (14 clicks).
It's even printed in the damn manual! (PDF link)

I needed a way to fix it, and in the process found an easy way to get more adjustability out of your regular Showas (even not doing this mod). (0-18 clicks of adjustability.)
Will post that next.
 

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Discussion Starter #50 (Edited)
Closeup comparison of cartridge lengths extended and compressed.
Will post numerical measurements later.

Keep in mind GSXR has a proper bottom-out, the Marzocchi's valves are hitting each other in that picture. The GSXR cart has more useable travel.

I am thinking if I shove a spacer above the topout spring on the GSXR and cut a bit of the preload spacer an equal amount, I'll be able to shorten the cartridge to match the Marzocchi exactly.

Also, need to make a post about the "cartridge seat/bushing" at the bottom of the fork...
 

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Discussion Starter #51 (Edited)
Unfortunately, this ride may be over.

Evolution Motorcycles (Santa Clara, CA) trashed my forks by not capping the ends before anodizing.

Because he didn't prep the fork properly, the teflon-impregnated internal coating the bushing slides against was stripped off (Marzocchi used it) and the bushing diameter was shot.

He also used SOFT anodizing (not hard), so not only does it scratch easily (it's already coming off in places), it will flake off and contaminate the fluid.
("MIL-A-8625 Type III, Class 2" aka colored hard coat exists... this is "Type II" aka soft coat)

I am not a happy camper.
I'm going to call and see what he's going to do about this.

(We talked about THIS VERY ISSUE before I dropped the forks off... and he said he bungs them. I'm hoping this was just an oversight and he will replace them.)
 

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Discussion Starter #53 (Edited)
Well, looks like Evolution Motorcycles is not going to do anything about it. :mad:
They want to "wait and see, use forks as-is" since they "never had a problem".

However, the paperwork clearly shows he didn't give any specifications to the plater for the job.
The Purchase Order has literally six words: "2 parts gold, 4 parts black"... that's it. Evolution's person that placed the order had no idea what they were doing.

The specification states that anodic coating thickness should be specifically called out by the purchase documents and/or the part drawing.
An example of a hard anodized and gold dyed finish designated by this specification would be:

"MIL-A-8625(latest version), Type III, Class 2 gold, 2.0 mil coating thickness, cap ends of tube, external surfaces only."
The picture of the adjuster cap shows why you do not soft-anodize the insides. (Google "third body wear".)
PTFE-impregnated hard-anodizing of the inside is possible, but requires expert care and specification of tolerances. Clearly, Evolution lacks that.


======================================



I had to push ahead with what I have, since I don't have any other uppers and Evolution won't replace the part. I used new seals, oil, everything.

(Option #2) a circlip rest had to be turned in the cartridge to accomodate the 748 stack sans "spacer". Floor is 11m up, standard 20x1mm circlip tolerance dimensions (tables online). I retain 18 clicks of adjustability out of 26 total before the compression adjuster screw binds (falls out?) internally.​

One more note: GSXR 750 workshop manual says fork oil weight is 5w with 100mm air gap, spring out. Marzocchi is 10w 110mm for Sport, 140mm for GT. Mechanic said 100mm / 5w Silkolene feels a bit compression-stiff in these, so may increase the air gap to 120 to compensate.

Will post ride report in a week or so once Valve Guides are done.
I will also post an pictorial how-to in a clean thread for "Option #3 - drill a hole".

If anyone has a cheap/throwaway set of stock Marzocchi uppers from a SportClasic/GT/PS, please let me know. It seems need to get a replacement set on my own. :(
 

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He Used Hard in black ,I couldnt scratch them if I tried. Im not sure if he capped the ends to be honest. No leaks and no problems but I would suppose so. I did not know that was a criteria at the time of doing it, but hes done it plenty before so Im sure he would know what hes doing. give him a call
 

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Discussion Starter #57 (Edited)
I did, actually :p I have some bolts on order from Rick. Just didn't ask about anodizing.

Can't re-anodize something twice... strips too much material off. So no point in me sending these out again.
I'm willing to bet bottom dollar if Rick did hard-coat, he had to have capped the ends. Else you get into PTFE-impregnation, DLC, rehoning, and expensive things.

Comparison of anodization types
Even with thinner, Type II anodizing, coating build-up can cause problems with tolerancing, for example, with very fine threaded holes, precision pin holes, and fine sliding fits.

The most common solution to this problem is to mask the features. This is done using soft plastic plugs, for round holes, or plastic tape or painted-on liquid plastics for flat areas.
I'd be more forgiving about the Evolution Motorcycles problem, damaging my forks, if they acknowledged the mistake... but they seem to think it's OK.
All facts say otherwise.

This is beating a dead horse, so I'll leave it at that... at least the warning is out there now.
 

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Discussion Starter #59 (Edited)
After talking with pajazo, who described the GSXR mod on the 900SS forks, I think we've identified another mechanism on GSXR cartridges that causes problematic behavior.

Below is an updated diagram illustrating K5 GSXR cartridge fluid flow. (The bottom is a "Ducati" compression bleed screw, but it's functionally identical.)

pajazo noted action #3 (fluid flowing up the sides of the adjuster rod and out the weep hole in the cap) throws off damping adjustments.

Torbjorn describes this briefly in Showa Blues #2 as having a '"proper" daming circuit lay-out' (sic), and recommends capping off the hole in the top with a M4 setscrew. The K-tech needles he uses are sealed by an o-ring, and he adds another one on the adjuster rod shaft.​

However, I believe this is a safety mechanism to ensure people can NEVER fully lock up their forks. Even if both compression/rebound screws are fully tightened, that weep hole (in conjuction with the rebound one-way check valve) allows oil to bypass the valves on both compression and rebound strokes.

(pretend #2 & #5 do not exist...)

Unfortunately, this also means the adjuster screws will never adjust to their full range. (AKA"Rebound affects compression damping")

Since #3 weeps oil on both compression and rebound stroke (due to high cartridge pressure), I think it also serves to constantly bleed any air in the cartridge. (from cavitation, etc) Again, a safety feature.

We're discussing the best way to eliminate this problem right now. pajazo will post pictures of K2 internals shortly, which he thinks keeps the bleed fully internal.
("External vs Internal bleed type." -- please see attached picture made by pajazo)

These are different names for the same thing:
"Crappy rebound circuit" = "short-needle" = "external bleed".
"Proper rebound circuit" = "long-needle" = "internal bleed"
GSXR appears to be some kind of "hybrid-internal-external bleed"​
 

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Discussion Starter #60 (Edited)
After e-mailing Torbjorn about this, I think we agreed it is far more important to properly select a shim stack than seal the weep hole completely.

Here is a link for a Vstrom tutorial which provides RaceTech shim stack suggestions that (coincidentally) line up PERFECTLY for our SportClassics... including the 1.3mm hole using a #55 tap drill bit.

Notice he puts the hole directly into the side of the valve... we can't do that since the GSXR valve is solid steel, and instead put it in the stack holder. But the principle is the same.... you can do it at home in your garage.




(Anonymized) shim tables attached for convenience.
Just remember: C32 is for lightweights like us. C39 is for Bowser.
 

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