Showa Twin Chamber 49mm conventional forks 96-98 RM125/250 + inverted Showas // RM & DRZ400 shocks & DRZ400 49mm forks!

[Chuck78]

Here's some of the best info on DRZ400 shock valving I've found:

https://www.thumpertalk.com/forums/topi ... t=10987650

and

https://www.thumpertalk.com/forums/topi ... tor-valve/

Terry Hay's valving stack is my #1 pick so far, tuned specifically for the DRZ shock with a rebound separator added. Chopperpilot noted to me that he was following those ThumperTalk threads on the DRZ400 shock valving as well, and was looking to settle somewhere in between MarekB's and Jeeper's DRZ400 shock stacks when using the DRZ400 piston specifically. I would tend to agree with something in the vicinity of those two combos as well, in my very limited experience.
This links directly to Kyle Tarry's post where he ran 4 Showa 50mm shock shim stacks in ReStakor, and posted a graph of them:
https://www.thumpertalk.com/forums/topi ... t=10994244
I've got a handful of open tabs on my phone of other Showa 50mm shock woods valving to sift through as well.

Stock 2002+ DRZ400 compression: ||
44 x 0.20 (4) . . . . . . . . . . . . . . . . . . . . .
44 x 0.15 (3) . . . . . . . . . . . . . . . . . . . . .
34 x 0.15 . . . . . . . . . . . . . . . . . . . . . . . .
26 x 0.10 . . . . . . . . . . . . . . . . . . . . . . . .
42 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
40 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
38 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
36 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
34 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
32 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
30 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
28 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
26 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
24 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
22 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
20 x 0.30 . . . . . . . . . . . . . . . . . . . . . . . .
40 x 0.30 (2) . . . . . . . . . . . . . . . . . . . . .
40 x 0.30 (2x, spacer) . . . . . . . . . . . . . .
41 x 4.00 (plate) . . . . . . . . . . . . . . . . . .
18 x 0.60 (spacer) . . . . . . . . . . . . . . . . .

Kyle Tarry revalve, compression:
44 x 0.20 (x4)
44 x 0.15 (x3)
34 x 0.15
26 x 0.10
42 x 0.20
40 x 0.20
40 x 0.30 (one shim taken from below)
38 x 0.20
36 x 0.20
34 x 0.20
32 x 0.20
30 x 0.20
28 x 0.20
26 x 0.20
24 x 0.20
25 x 0.60 (spacer due to shorter/modified rebound stack, shim is from stock rebound stack)
40 x 0.30 (spacer)
41 x 4.00 (plate)
18 x 0.60 (spacer)
,

Jeeper's Revalve, compression: . . . ||
44 x 0.20 (x6) . . . . . . . . . . . . . . . . . . . . .
44 x 0.15 (x5) . . . . . . . . . . . . . . . . . . . . .
30 x 0.15 . . . . . . . . . . . . . . . . . . . . . . . .
26 x 0.10 . . . . . . . . . . . . . . . . . . . . . . . .
40 x 0.20 (x3) . . . . . . . . . . . . . . . . . . . .
38 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
36 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
34 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
32 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
30 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
28 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
26 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
22 x 0.20 . . . . . . . . . . . . . . . . . . . . . . . .
25 x 2.0 . (spacer for washer/nut) . . . . .
.
.

MarekB's revalve, compression:
44 x 0.20 (9)
44 x 0.15 (6)
38 x 0.15
30 x 0.15
42 x 0.25
40 x 0.25
38 x 0.25
36 x 0.25
34 x 0.25
32 x 0.30
30 x 0.30
28 x 0.30
26 x 0.30
24 x 0.30
22 x 0.30
25 x 2.0 (spacer for washer/nut)

DRZ400-shock-revalve-curves.jpg (27.19 KiB) Viewed 9226 times

Apparently the rebound bleed hole orifice on the DRZ shock piston is sized larger than most other 50mm Showas, so the DRZ based valving may have slightly different requirements than an RM shock or a new one on my radar the 2024+ KX450X / 2025+ KX250X 50mm Showa (& the standard F model KX450/250 MX versions).
The rebound separator valves that flow differently compression vs rebound (instead of the rebound adjuster circuit altering compression damping as well when adjusted) need the end drilled out for orifice size based on many factors, but Terry Hay specifically says for the DRZ400 shock, that the "rebound adjusting circuit bypass" is as large as they come, and this is why he recommends when drilling a rebound separator valve to size it for a DRZ400, that a 1.4mm bleed orifice drilled into the rebound separator.
I believe this photo illustrates (RT Gold Valve shock instructions) the rebound bypass / bleed orifice that Terry Hay is talking about?
I see a 2001 RM125 Showa shock on Race Tech's product search page states to drill a 2.8mm bleed in the rebound separator. I would wager that the rebound separator orifice drilling size recommendation is directly correlated to the size of the shock piston's rebound adjuster bypass orifice sizing.... RaceTech no longer shows a rebound separator valve for the DRZ400 years I checked (several), but Terry recommended 1.4mm, and so I'd bet that with Race Tech recommending the 2.8mm rebound separator orifice drilling for the 2001 RM125, that the DRZ400 shock piston bypass hole will be significantly smaller on the RM125 Showa piston vs the DRZ400 being significantly larger!

SK_REBUILD_RESY_DSC_0180-600-BLEED-HOLE.jpg (30.42 KiB) Viewed 9261 times

On the DRZ400, run a 1.4mm bleed on the rebound separator valve. Normally you would drop a couple of low speed shims (2 x .20 x 44) in order to accommodate the additional force provided by the RSV. This is once you have a good valving set up. On a normal shock say YZ250F, I would use a 2mm bleed with the same low speed compensation.
The DRZ400 is notoriously soft on LS damping as well as having the largest rebound adjusting circuit bypass. There is a common theory that in order to have plush initial feel with bottoming resistance that you should have a soft LS with more HS damping. This is where a lot of set ups fall down.

As a DRZ owner you should be aware that a fistfull of throttle will see that thing squat badly to the point that you almost slide off the back of it. The RSV will really help here as will more LS. Get this right and you wont need quite as much HS.

The benefit of the RSV is in the stability it provides. You only remove some LS "once you have a good set up" and add the RSV to the system. With the stock DRZ400 valving, you will still benefit from extra LS even with the RSV in place. The DRZ400 shock rebound damping isn't weak at all. Rebound only occurs as a consequence of compression. Once you get the comp under control I doubt you will have a rebound issue.

Regarding no_hand's '06 RM250 RSV and valving difficulties, 1.5mm is too small for that shock. 2.1mm would be more appropriate.
Also, you have to be careful that there is enough clearance between the underside of the top of the valve and the rebound port otherwise you can restrict the pop off valve function.

Here's just a friendly reminder that one needs to approach DIY revalving, even when copying someone's pretty successful settings for their machine, with the understanding that even pro shops don't always it right the first time typically, unless they are HIGHLY FAMILIAR and HIGHLY EXPERIENCED with your particular model and have an exact understanding of the terrain that you ride and your riding style/abilities.. Drew Smith and company at Works Enduro Rider / WER Products have been in business longer than most, and have extensive experience and an extensive database of valving combos, including both the '96-'98 RM forks and the DRZ400 conventionals, and I'm sure could do wonders with the 50mm Showa shock setup as well.



Here's another good one several pages beyond the link above, with some detailed info (in a DRZ400 revalve thread primarily about the forks) about the shock compression adjuster stack, very detailed hand drawn sketch of the adjuster, and a ReStakor modeling chart of the valving... page 12 on my browser midway down, by McGyver:

https://www.thumpertalk.com/forums/topi ... t=12543148



Also a note for disassembling and revalving the shock shaft/piston on all Showa shocks, per Race Tech's shock Gold Valve install instructions (still pertains to any revalve even with stock piston).

https://racetech.com/ip-sk-valving-std/

Look at the special note for Showa shock revalving when removing the peening on the end of the shafts. You have to file around the edges of the shaft protruding above the nut to remove only the peening/staking, NOT filing flat across the top like you would on a KYB or basically any fork base valve.
The rebound adjuster has a bleed orifice seat in there that the staking/peening holds in place, and you must not file into that otherwise the adjuster will be rendered useless!!!!

SK_REBUILD_RESY_DSC_0103-600.jpg (38.79 KiB) Viewed 9265 times

SK_REBUILD_RESY_DSC_0124-600.jpg (36.53 KiB) Viewed 9265 times

[Chuck78]

Screenshot_20240930-160717~2.png (644.32 KiB) Viewed 12713 times

Also, I found that JFG makes cheap billet aluminum anodized front rotor guards for the DRZ400 (& '97-'98 RM) Showa 49mm conventional forks!
$35 on eBay or AliExpress, as low as $23+$4 shipping on AliExpress if you prefer blue instead of gold anodized.

https://jfgmotor.com/products/front-bra ... XUgAYCq9rp

[billie_morini]

Wow! Britannica encyclopedia and Wikipedia do NOT hold a candle to Chuckpedia!

thx, Chuck. Copied and filed on external hard drive for future reference.

[Chuck78]

The DRZ400 clevis made contact with the top of the KDX's suspension linkage rocker at top-out, but I was still able to tilt the shock forward to get the frame's upper shock mounting bolt through the shock, although it does need filed slightly.

The '01-'04 RM clevis, with it's rocker mounting bolt holes located 5.5mm higher (shorter clevis), won't even come close to tilting forward to bolt unto the upper frame mount without some significant filing and dremel work to bevel the front facing horizontal surface crotch edge of the clevis.

Screenshot_20240930-175316~2.png (2.62 MiB) Viewed 12707 times

The '98 RM shock looks great installed, but is a close fit in a few areas of the frame, one which really needs massage by grinding off unnecessary metal on the edge of the flat steel stock making up the upper shock mounting point on the frame, the lower right rear side needs a bit of excess trimmed off to not rub the shock body when topped out.

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Reservoir clearance on the '98 RM125/250 shock is close to the frame, but clears and works. With the full weight of the bike on the ground, the shock will swing backwards, giving more clearance. The modern Showa 50mm shock is such a significant upgrade that I'll go to great lengths to make it fit perfectly.

Screenshot_20240930-182319~2.png (2.12 MiB) Viewed 12705 times

****Here's where no one prior had made any comments about required spring clocking due to engine case interference... You need to rotate the spring so that with suspension topped out, the gap in the coils is aligned with where the spring would otherwise rub the engine case swingarm / engine mount bolt area.
As soon as travel starts, the shock moves further away from the engine case, but at initial travel, this needs to be clear and aligned strategically. I have no issue filing a bit of clearance into the engine case halves here (the area is 10mm thickness at left and right, but thinned to roughly 7mm guesstimate in the entire area in question), as this is a substantially improved rear suspension over stock... I just wouldn't want to file all the way through into the bore of the swingarm/engine mounting bolt - I'd drilled a small pilot hole through to witness the material thickness as to not grind all the way through it.

Screenshot_20240930-180017~2.png (1.93 MiB) Viewed 12707 times

.

[Chuck78]

Here is a link to a pdf scan of some very detailed Showa shock rebuild instructions. No photos, but extremely descriptive. The bleeding procedure and making sure the rebound adjuster needle assembly is installed and set up correctly are critical.

https://www.southbayriders.com/forums/a ... ts/452117/

[Chuck78]

More shock swap observations and info.

Browsing the Teknik Motorsport website, a big aftermarket suspension company based in Australia, they give specs on all these shocks... I've found they're not all 100% accurate, but... it's been a nice helpful tool to get some ideas for shocks to hunt down in the name of long travel ultimate KDX mods...

50mm Showa shock swap candidates:
'02-'24 DRZ400/400E/400S shock 450mm length / 128mm shaft travel / 60mm clevis length
'02-'24? DRZ400SM shock is 446mm length / 124mm shaft travel / 60mm clevis length (4mm taller piston + 4mm lower step on shaft)
'01-'04 RM125 shock is 448mm length / 130mm shaft travel / 55mm clevis length (one of mine measures 450mm? longer shaft or top-out bumper worn?)
'98-'00 RM125/250 shock is 454mm length / 133mm shaft travel / 60.5mm clevis length (measuring my '98 RM125 shock)
'96-'97 RM125/250 same as '98-'00 except smaller 46mm piston/body and smaller diameter spring)
2024-2026 KX450X & I believe KX250X have allegedly a 32mm shorter shock (vs 475mm '19-'23), so 443mm perhaps!?!?! So these may also be an awesome swap. The X is the GNCC enduro racer version with softer suspension than the MX versions. The SR version is the factory A-Kit/Works type MX model with suspension that's significantly more $$$$

I have two '01/'02 RM125 shocks, measured 448mm and 450mm, Teknik lists them 452mm '01-'02 and 448mm '03-'04, FYI. Everything here is just approximate due to my measuring & actual years of shocks vs what they were stated to be off of. I have found Teknik to have many errors though.


I've found several other errors in Teknik's measurements, but have gotten better at using a flexible steel ruler with the shock mounting bolts as extensions to reach where my ruler sits off the shock body, and measuring top end to top end of the mounting bolts to get more exacting centers, as my 12" Mitutoyo calipers do not extend to 16.75"-17.75" length, that would make this too easy!

They advertise 140mm shock travel on all '01-'04 RM125, but both of these here have 130mm travel, and Teknik's total shock length is roughly the same as mine (mine are not lowered internally). I believe their '98 RM travel is also 10mm greater than actual measured travel @ 143mm (measured 133mm by me).

So the '01-'04 RM125 have the 5mm or 5.5mm shorter clevis, 98-00 RM125/250 and DR-Z400 have the shorter style body, and the '98-'00 RM125/250 as well as the DRZ400 through 2024 model year have the shorter lower spring seat which may be very helpful when lowering the shock 10mm, so you don't run out of room to back off the shock spring preload.

Also, the '96-'97 RM125/250 shocks are exactly the same clevis/shaft/body lengths as the '98-'00, except 46mm body/piston and correspondingly smaller diameter spring, so this shock could also be lowered 14mm (or use a taller KYB 46mm sealhead??? as part of the lowering) and not have the spring coil spacing requirements or crankcase mount area clearancing issues...

One could really build a longer travel version combining parts of these various shocks (stock 118mm shock travel yields 300mm / 11.8" wheel travel) using the DRZ400 shock body or the '98-00 RM body (both bodies are same length, but different reservoir configuration, both equally shorter than the '01-'04 RM125 bodies) and the shorter '01-'04 RM125 clevis, or dismantle and weld up the mounting bolt holes in the clevis and move it higher 5mm like the '01-'04 RM125.

300mm advertised KDX200H travel ÷ 118mm stock KDX shock shaft travel = an average suspension leverage ratio of 2.5424.

Using the DRZ400's 450mm length, minus 5mm for swapping in the shorter '01-'04 RM125 clevis to free up shaft extension ability (needs lowered less then), at 445mm, this only needs lowered 5mm roughly, and as such, you end up with 128mm shaft travel minus 5mm = 123mm shaft travel x 2.5424 Leverage Ratio = 312mm / 12.28" rear wheel travel!

The DRZ400SM has a taller piston/lower step cut on shaft, effectively lowering it 4mm as stock, adding another 2mm internal lowering spacer (to 122mm shaft travel) and welding up that clevis and moving the mounting bolt hole up 5mm - will give you the simplest mods to a 1-shock-does-it-all long travel KDX FrankenShowa swapped rear end! Or just run the 400SM shock with 6mm of internal lowering spacers, and you have the same travel as the stock KDX shock... All these shocks could stand to have hte valving revised slightly, and the DRZ is a well documented platform on ThumperTalk.com for suspension valving, FYI... The SM is a street supermoto version so will have a different valving, but still fairly off-road friendly.

My '98 RM125 shock (I believe '98-'00 RM125/250 will be same) @ 454mm, minus 5.5mm for the shorter '01-'04 clevis swapped, = 448.5mm, minus say a standard off the shelf 10mm sealhead lowering spacer for convenience, = 438.5mm length
133mm shaft travel minus 10mm sealhead spacer = 123mm shaft travel (same as the DRZ) = 312mm / 12.28" rear wheel travel!
You could do a custom 8.5mm lowering spacer and perhaps "heat up and clearance" the KDX frame slightly where the rocker tops out against, so it does't top out against the frame, and run the shorter clevis on the 98 RM shock with 440mm total length (about 8.5mm of lowering spacers), and achieve 316.5mm / 12.46 rear wheel travel. That's monstrous! And still will clear the fender at full bottom-out compression with 117mm KLX300 pull rod links leaving the rear end a hair over 1" taller than stock! That may even clear the fender on full compression bottom-out with my fat 120/100-18 Shinko 520DC rear gummy tires!

It seems that either of these two with the 01-'04 shorter clevis or whole shaft and appropriate internal lowering spacer stack height will be the way to get longer travel, and you get the shorter spring seat needed as well since anything we're discussing needs internally lowered which means backing the shock spring preload off the same amount.




Stock KDX200H shock shaft travel = 118mm with no bottom-out bumper in place (the Showa foam bumpers compress to less than 2mm @ bottoming, surprisingly)
Stock KDX rear suspension specs @ 11.8" / 300mm advertised travel

The DRZ400 '02-'24 shocks will be the best single shock to run (meaning without combining parts from 2 different shocks), and the slightly longer clevis means you don't have to bevel the clevis nearly as much, nor clearance the rocker knuckle for the screw in the bottom crotch of the clevis as much or at all... You should end up right at stock travel with a 10mm lowered DRZ shock, but 1.1" taller rear ride height using KLX300 suspension links or Kouba KDX1 links.
450mm-10mm lowering spacer = 440mm max shock length, add KLX300 117mm suspension links and their longer bolts (steel versions may still work with KDX bolts but they're slightly thicker, aluminum KLX300 versions require the much longer KLX300 linkage bolts) will get you the simplest modern shock upgrade to increase compression adjustability options with a dual adjuster, increase shock oil capacity for cooler running and longer service life and also increased piston size for longer shim life and better tuning abilities, AND to raise the rear end ~1" to match all the "BEST" fork swap options that are generally all 1" - 1-1/4" taller forks, adding ground clearance and suspension travel to your KDX - shave the seat foam 1" if you want to put the tip-toeing height back to stock for confidence/convenience. You could even make your own lowering links or get some Kouba KDX2 links, I think the Kouba KDX1 I believe very similar to the KLX300 117's, the Kouba2 should put the rear end height back to near stock.


On a side note to check my estimates above, with my '01 RM125 shock mounted, granted sloppy linkage bearings slightly skewing topped out & bottomed out measurements, I measured 119mm installed available shaft travel. 449mm - 10mm + 439mm, 131mm shaft travel = 121mm travel which is near right on at my 119mm actual measurement, although the old linkage bearings may have given a hair extra extension, so say 118mm. I have a definite margin of error on all my rough measurements and calculations, but closer than some of the Teknik Motorsports' website specs!

Great news here after all these evenings geeking out, deliberating over online info, buying shocks, measuring, testing testing testing...


I'd recommend anyone to mock theirs up after clearancing the clevis, with rear wheel hanging in the air, and measure the actual available shaft travel (amount of shaft exposed with suspension linkage topped out and swingarm hanging to pull the shock down to full available extension), & then remove the shock to check the actual maximum shock shaft extension, and then give yourself a stack of 16mm-shaft-size internal lowering spacers with a stack height totalling the difference of available Showa travel installed vs fully extended available travel off the bike. Add maybe 1mm more in internal lowering spacers to protect the rocker linkage from topping out on the frame, & then build your shock up based on that length
Or just start out with the 10mm sealhead "30mm lowering" spacer from Zeta Racing for Showa 50mm shocks and double check the topped out rocker linkage vs the frame crossmember in front of it, as well as seeing if you can fit the 10mm lowered DRZ400 shock without compressing it any (then my numbers would be dead on if so!).

[Chuck78]

Stock KDX200H shock shaft travel = 118mm (300mm advertised rr.whl. travel = 2.54:1 leverage ratio)
'02 DRZ400E (all 400/400E/400S?) = 128mm (295mm advertised suspension travel = 2.31:1 leverage ratio)
'01-'02 ('01-'04?) RM125 shaft travel = 130mm (320mm advertised rr.whl. travel = 2.46:1 leverage ratio)
'98-'00 RM125/RM250 shaft travel = 133mm (315mm advertised rr.whl. travel = 2.42:1 leverage ratio)


These crude approximations of leverage ratio will help in comparing the valving of each shock to the KDX's linkage, and help to make adjustments to the amount of damping force overall when switching the shocks onto a linkage system and swingarm length which are not quite their original leverage ratios.

It's late night and I'm trying to grasp the changes here in those numbers. I hope I'm envisioning this correctly.

A higher suspension leverage ratio means LESS shock/spring travel vs MORE wheel travel, so the spring rate would need to be higher for one. The damping would also need to be more firm in order to control the suspension movements.

A lower leverage ratio number would mean more shock piston travel for the same wheel travel, and would require less spring rate, and the shock piston speed would be much greater for the same wheel speed, so the damping forces would need to be less restrictive for the same wheel travel vs a higher leverage ratio linkage geometry/swingarm length.

Someone please correct me on that if I'm wrong.


Looking over at ThumperTalk on this subject, where many experts on suspension valving always reside, a very knowledgeable suspension expert with a familiar name DEATH_INC. chimed in:

Yes, except with a lowering link the guard becomes the travel limiter, not the shock.

The wheel moving faster in comparison to the shock shows an increase in leverage ratio, which has the same (or at least very similar) effect as softening the shock, both in compression and rebound. You're actually pushing the oil through slower. I actually suspect the difference won't be that great at the lower end of the curve.

and on a slightly different subject area, but in reply to the above:

Your suspicion is pretty inline with what I've learned (at least on the Yamaha).

In my track testing of a 1.5mm longer YZ link length, the longer link was just slightly softer early in the curve and it delayed the major increase in ratio until later in the travel. The delay was the more significant of the two effects. It was great in some flat or slick corners, especially when steering with the rear end or scrubbing a jump. It was terrible in the whoops (Washougal this summer) where the bike wallowed and I couldn't consistently get a forward drive because it was moving up and down too much. That feeling was confirmed by a rather savvy local pro buddy who was watching that race, he observed exactly what I was feeling.

Looking at my bike hanging from the basement ceiling as a makeshift "motorcycle lift" work stand, and swapping suspension pull rod links, it became pretty clear that the main leverage changes occur from swapping a different rocker knuckle in, and behind that, altering the shock length which puts the rocker in a different position in it's curve. Adding a different length pull rod / dog bone link set has a minor effect but still contributes. A longer pull rod link set primarily just changes the swingarm position. It has no change in the rocker, although the differing angle of the swingarm vs rocker linkage via the connection of the pull rod links will be slightly altered, which is where the changes in the traits come from above on the YZ referenced.
If there is a significant change in suspension traits with the 117mm links vs stock 112mm, I have the KLX650R 115mm links that I can swap in. From hearing feedback on Kouba KDX1 links, there is very minimal change in the damping action when lowering the bike around 1" (almost the exact lowering link length as the KLX300 117's). If I swap in the 115's, the ride height will increase, but I can back off the shock spring preload to lower the height again as well as get some more initial plushness.


https://www.thumpertalk.com/forums/topi ... t=15885632

more:

A rod with 4mm longer length wont change the leverage curve dramatically enough to matter. A bellcrank that changes the shock placement to alter geometry will majorly affect the leverage curve and the average leverage ratio.

[Chuck78]

I'd originally been contemplating to cut & fabricate an extension to the KDX200H/220R upper shock mount to relocate it 16mm higher and roughly 6.5mm rearward, so that I can use the full '98-'99 (& '00? - Teknik's website specs show a slight variation in size on 200) shocks with the aftermarket Lainer Suspension compression adjuster or '02+ DRZ400 compression adjuster, and have the option to swap to the shorter '01-'04 RM125 clevis and even shaft if I desired a lower rear ride height... After finding I'd missed the true shock shaft travel in the KDX's shock (perch bottoms out with 13mm of shaft still exposed, vs the Showas which will bottom out only when all available shaft has traveled into the sealhead cap). This made me recalculate and realize that even with a 10mm sealhead lowering spacer, the DRZ and '01-'04 RM125 shocks will still have the same travel as a stock KDX. I was worried I'd be lessening the travel slightly, but this is not the case, only will we be raising the ride height... the KLX300 pull rod links will bring it back down to manageable height, but moving the shock mount upwards and running an RM125 shock could bring it near stock ride height, with attention paid to not giving more shock travel / wheel travel than the tire vs fender have clearance for.

The rearward movement will help the engine case clearance and keep from cutting into the frame crossmember to get the adequate height (possible but would need additional bracing/gusseting), but I'll need to see how far the middle of the shock spring moves rearward during suspension travel to verify how far I can go without a bottomed out shock/spring rubbing the airbox boot.

The 133mm shaft travel of the '98 RM250 shock I have could yield 13.3" travel...After revising my calculations based on the actual KDX shock shaft travel to achieve the advertised 300mm rear wheel travel, I realized this is not so necessary to relocate the upper mount much if any at all.


I feel that adding 1" - 1-5/8" ground clearance is a huge plus for hard enduro type terrain, and then I can run modified Yamaha 2000's footpegs that are offset 1/2" lower, and also shave my seat foam about 1" up front tapering to 5/8" shaved in the mid/rear, to lower the standover tip toeing height back closer to stock. This will all improve the bike in the hard enduro terrain. I also am going to start running a longer chain, as the steepness of some of our technical climbs really challenge me to keep the KDX front wheel from lofting and nearly looping out when on the throttle in the steep gnar... The short wheelbase is really nice for whipping around in tight trails in between the trees though.

[Chuck78]

I'm out with a fractured wrist for the reminder of the season, but becoming more active as the bones are starting to heal (with the help of a surgical screw holding my scaphoid halves back together!).

I spent a little time one-handed looking into shock lateral movement through the stroke vs airbox boot clearance.
Compressing the shock to the bottom out bumper, the lower end of the shock moves a significant amount rearward, no clearance issues there aside from the topped out starting point I'd mentioned previously with the shock spring coils needing rotated into necessary clearance alignment in order to not hit the crankcase's rear swingarm/case mounting bolt area.
At the top of the shock, the airboot has a larger clearanced area where the shock spring is adjacent, but is much closer at the top of the shock body above the spring. This clears by about 5.5mm still at almost full bottoming (I didn't compress the bottoming bumper). It moves probably 5mm rearward closer to the airbox boot during a full compression stroke however.
This test was done by me as I wanted to see how far back I could get away with relocating the upper shock mount to help slightly with the clearance at the lower end...
What I'd gathered is that I can bend the upper rear airbox mount z-bend more straight and rearward slightly to gain a touch more airbox air intake boot clearance as to be able to cut, extend, and reweld the upper shock mount 5mm-6mm rearward as planned and 16mm roughly upward, as to be able to utilize the full travel of the RM125 shocks or near it, and and not worry about any significant internal lowering of the shock to prevent it from topping out.
Without raising the upper shock mount higher, we'd be very slightly different reducing the overall available travel just a touch with any of these shock upgrade combinations. Less than 12mm travel reduction, hardly noticeable, and a short chain vs long chain axle adjustment covers probably a similar amount of travel gain/loss.

[kirkpz]

Hi Chuck, Do you know if the hi/low speed adjuster on the 2001-2004 Rm 125 shock works in the 1998 body or the Lanier adjuster fit in the body of the 1998?

[Chuck78]

The adjuster seem to be the same to me between the shocks I have, 1998 and 2001 RM 125 as well as 2002-2024 DRZ400. The Lainer threaded directly into the '98 body. I don't have this shock build finalized yet, as I have way too many projects that I'm always juggling, mostly for the wife's bikes & vehicles, and house work... But I've been meaning to go back and double check the internal depth, but it all seemed pretty identical to me when I had them in my hand comparing them.

[kirkpz]

thanks. I have the 2003 rm 125 shock also and maybe that would fit in 1999 body. I will check when I dissassemble.