KDXRIDER.NET

Below compiled various KDX upgrades & using improved parts from KX's and others
(with A LOT of info from Art Simmoneau "artstoy" on this forum)



Alloy & sealed knuckle shorty & full length kickstarter levers:

I've got both the full '96 KX250 setup with the longer alloy lever, as well as the 96 KX250 splined knuckle + the "shorty" 96 KX125 lever, and both are awesome and a big upgrade in ergonomics as well as weight savings and lifespan, versus the stock goofy, hockey stick, wear-prone open knuckle OEM KDX kicker.


Fredette Racing Products sells a cast aluminum custom kickstart lever that is of the "shorty" variety like the 1988-1990-ish(?) KX125 lever, and it slips right onto the splined knuckle/boss portion of the KDX kicker lever, to ditch the long worn out awkward hockey stick KDX kicker with a lighter more compact sized lever for more swift fast kick action.
1994-1998 KX250 kick start lever splined boss/knuckle + the "shorty" 1994-1998 KX125 (1992-2000's KX125??? & various KX100???) kicker lever (or the longer '94-'98 KX250 aluminum lever also) is an excellent upgrade to get a closed knuckle sealed kicker pivot design with a lightweight aluminum kicker lever.
The splines are slightly narrower, requiring a custom ground to fit washer/spacer size for proper torquing onto the KDX kicker shaft splines, or else get a larger smooth faced flanged hex nut of this size and counterbore the first 1.0mm or less of threads out so that it gives a step to fit over the remaining exposed splines.



Here's a full '94-'98 KX250 sealed knuckle aluminum kicker lever & splined knuckle (+ a custom dremeled washer as a spacer):




Around I believe a 1988-1990-ish KX125 lever will slip straight onto the stock KDX kicker's splined boss/knuckle as well, but is still the open knuckle design. Verify open vs closed knuckle design years via photos first please.
2007+ KX250F kickers have become a popular aluminum alloy closed/sealed knuckle kicker KDX upgrade as well. These have curvature in them to fit around the pipe mount/etc. This has the same issue with slightly narrower spline length than the KDX splined kicker shaft, requiring a washer or a counter-bored nut. These require a slight bit of grinding / flap disc sanding on the actual aluminum kicker lever portion in order to clear the clutch case I believe. There is other info in posts on KDX Rider forum about fitting these levers.
From Art Simmoneau:
"Take the whole kickstarter and grind, sand, and polish the back of the aluminum part of the knuckle to clear your clutch cover when kicking it down (don't worry, there is an excess amount). Now, the splined knuckle that fits your kickstart shaft is a few thousandths thinner than the KDX's, so when you tighten the nut down, the lever splines still have a little play on the shaft. Two fixes - buy a shouldered nut and counter drill it on the shouldered side just enough to take up the slack and just large enough diameter to go over the splines. Or else find a machine bushing that just goes over the splines. You could technically take a file or a hand grinder and just cut the splines back just a shade to take up the distance but its a lot more work, I prefer the first method."

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*the 3 photos below are for the next post, as I've exceeded the amount of file attachments per post

Aluminum shifter pedal upgrades, & larger splined shift selector shaft upgrades:

'93 & earlier KX125/250/500 shifters OEM and AS3 Performance or Apico (aftermarket cold forged shifters) are aluminum and a direct fit to the stock KDX shifter shaft's reduced spline diameter, as the KX shafts vs spline diameter are the same dimensionally.
You can't get a Hammerhead brand shifter specific to these '83(?)-'93 KX125-250-500 models, but a KX100/KX112 shifter will be exact fitment on the splines although I'm not certain the length will be the same, as they are for smaller riders. I personally didn't notice any difference in the length of the shifter while riding a 2022 KX112, which is an absolute missile of a mini professional motocross bike, fyi!

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If you want a larger diameter longer lasting spline for use with the larger diameter spline 1994+ softer (aluminum vs steel) shifter pedals, the shift shaft in the KDX200/220 engine has to be upgraded to the '94-'02 KX125 shift selector shaft with some light mods. Here's 2 bent small / reduced spline size stock KDX220 shift selector shafts, with a '94 & a '98 KX125 full spline size shift selector shafts:

'94+ KX125/250/500 2-stroke and KX250F '06-'18 shifter levers/pedals use full sized splines (same diameter as the rest of the shift shaft - unlike the reduced spline vs shaft diameter on the KDX and '93&earlier KX), and the KDX can be retrofit to a later (possibly as many different models as the 4 different KX125 part #'s '94-'02) KX125 shifter shaft, more details coming soon as I've just purchased a 1994-1995 version KX125 shift shaft.

Art Simmoneau has modified a 1999-2002 version to fit the KDX200/220. He uses the inner fork portion from the KDX shift shaft after removing it by grinding two wrench flats on the retainer/flanged portion of the pin's "head," grinding a pair of parallel wrench flats down to the pin diameter on the pin that retains this inner moving fork/pawl piece, and then grabs it with a wrench and rotates it 90 degrees (it's basically riveted in place on the welded on outer pawl/fork that's welded to the shaft) so that the inner fork/pawl piece will just slide off instead of being held captive. Then he grinds the other fork/pawl, the KX125 fork/pawl piece that's welded onto the end of the shift selector shaft, down slightly to match the profile of the KDX welded-on portion, then slides the KDX inner removable piece back onto the KX125 shaft, and rotates the riveted pin back 90 degrees so that the remaining portion of the flange retains the moveable piece again despite having two wrench flats ground onto it. Art then tack welds the back side of the riveted pin onto the welded-on fork/pawl piece just so that it won't rotate ever.



The EARLY-'94 version KX125 shift shafts (fits '94-'95 models) just have this riveted pin, but with no "head" on the pin to grind down and rotate parallel to the slot for removal, so this piece is able to be easily swapped out.
Also, I purchased the '94-'95 KX125 version (& a '98 on the way), in hopes that it or the 1996-1997 version may be directly swapable into the KDX engine, but have not yet verified. 1998 was a 1-year-only KX125 shifter shaft (looks almost identical to '99-'02), and 1999-2002 is the last one that's a possible option. 2003+ or 2004-2005 (2008 internationally before the end of the KX125 2-stroke) has a different design on the welded-on fork/pawl piece on the inner end of the shaft, so this is less suitable.

This comes from the factory with a round head, Art came up with the clever solution to grind wrench flats on this to be able to remove the KX125 fork/pawl and slip on the very slightly shorter KDX version, and then rotate the pin with the wrench flats 90 degrees so that it again acts as a retainer as it's designed, and then tack welding the riveted backside to keep it from being able to rotate out of it's now necessary orientation:




The inner portion of the welded on fork piece has a large ovalized slot (that a pin travels within) that needs to be ground out taller in order to facilitate the same amount of travel range as the KDX part that is welded to the KDX shaft. The length of the "ears" the welded on fork piece also need to be shortened up as you will see when holding it up to the KDX part that they protrude a millimeter or two further towards the front of the engine. Very basic grinding to adjust these.


The 99-02 which Art used did require grinding wrench flats on the head of the pin in order to remove the forked piece that rotates on the shaft, in order to facilitate the grinding of the slot in the welded on portion larger than what it is to match the KDX part. I'll check the next time I'm in the shop to see if the earlier versions need this slot ground out taller or not.


KX250F 2006+ billet CNC'd Hammerhead shifter vs '94-'08 KX125/250 2-stroke forged aluminum Hammerhead shifter:
Art stated he prefers the KX250F version aluminum shifter, as it's slightly longer for his large boot size, and cam better accommodate a larger boot size 10 or 11 US and up, but also, Hammerhead sells replaceable offset shifter tips that are 10mm and 20mm further forward and swap directly onto their billet & their older forged shifters with removable pins (the "Moose Racing by Hammerhead" versions have a permanently riveted on tip). Art also stated that the KX250F shifters '06-'18 require a bit of grinding in order to seat properly on the splines, I thought he was saying they sit too close to the case, but now after receiving one I realized that the bolt threads are drilled in a slightly different (offset inboard) position which leaves these shifters 1mm more outboard so that they don't get full spline engagement unless you are to grind a little bit on the actual shift shaft where it is slotted for the bolts to slide through as a fail safe retention method, which is how you cannot pull the shifter off without completely removing the actual bolt so that if it comes slightly loose, so that it doesn't fall off on the trail. You wouldn't need to do the shaft 360°, only the portion where the bolt touches. I did consider perhaps just grinding the threads on the bolt itself closer to the head where it never has to thread into the other side of the pinch clamp portion of the shifter pedal. This would however allow the shifter to accidentally slide out a bit further if not fully tight, although even the stock shifter and KX shifter can move in and out a bit, so this should not be an issue.





*Avoid the cheaper Moose (my smaller '93& older KX Moose shifter isn't holding up so well in terms of spline wear), Tusk, and various "Amazon" and AliExpress brands, as these will surely be more likely to break off in a lay-down crash.



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Aluminum brake pedal upgrades:
The forged aluminum brake pedals from KX and KXF models can be fit to the KDX as follows. The aluminum brake pedal and aluminum shifter will give up to a total of 1lbs difference in weight over the stock steel KDX versions.


The KX500 (AirTime brand on ebay @ $65, & OEM Kawasaki) brake pedals are a direct fit to the KDX frame.
Later KX250 brake pedals can be used, but have a larger pivot diameter.



The AirTime KX500 pedals appear to be simply just an '03-'08 KX250/125 or 2006-2018 KX250F forged aluminum brake pedal with a bronze bushing(s) pressed into the larger pivot bore.
No commercially available single bushing will fit this, but you can get bushings with more material and drill out or turn down the outer diameter on a lathe, OR... two 11mm i.d. x 17mm o.d. 11mm(???) wide or wider can be pressed in with retaining compound and filed flush, and then they fit the stud welded to the KDX frame. Diameters are from memory, please measure before buying.

These welded-on KDX brake pedal pivot studs are wear-prone items, so it's really better off to buy a 2000+ KX or 2006+ KX250F replaceable pivot stud (large shouldered bolt) and cut/grind off the stock KDX's worn steel stud that's welded on, and either always use an M8 stainless locknut on the backside, or else weld a nut to the back side of the KDX frame to receive this replaceable stud. The replaceable studs have two o-ring grooves, as well as a center groove to retain a fair amount of molybdenum chassis grease, which is a big upgrade over the open and wear prone KDX setup which allows dust, dirt, sand, and grit to enter the pivot area. You can buy these replaceable brake pedal pivot studs in titanium from Factory Image Racing dealers, or RaceTech Titanium, etc.

So what I'm reading from others trying various KX pedals, is that the '04-'05 Kawazuki KX250F/Suzuki '04-'07 RM-Z250 pedal looks like it will work but sits too close and touches the clutch case. However the 2006 - 2020 KX250F has the correct offset bend.

The 2-stroke KX models have a 2000-2008 brake pedal pivot stud (also '04-'05 KX250F/Suzuki RM-Z250), 1997-1999 brake pedal pivot bolt, and 1995-1996 KX125/250. The 06-'18 KX250F seem to be reportedly a good fit to the KDX clutch case housing/cover as well as the '03-'08 KX125/250 2-stroke as run by Art Simmoneau, and possibly other models. The 06+ 250F and '03-'08 125/250 2-stroke (possibly 2000-2008 interchange?) will be the ones with the biggest aftermarket availability / most quality offerings.

The KX models used this style of removable replaceable brake pedal pivot pin starting in the 1995 model year, using one replaceable pivot stud bolt for '95-'96, a different part number for '97-'99, a different part number for 2000-2008 KX125/250 2-strokes and '04-'05 KX250F / it's sibling the '04-'06 or '04-'07 "Kawazuki" Suzuki RM-Z250, and then a different part number for 2006-2010 and then 2011-2023 KX250F, the brake pedal I'm most interested in getting a hold of as being the newest (2006-2020 interchange on the KXF brake pedal), there are probably more high quality offerings on the aftermarket such as the actual Hammerhead brand forged brake pedal.



Here's a good discussion of the two different methods of fitting the newer style pedal onto a kx500, which will be similar to the KDX:

http://www.oem-cycle.com/forum/viewtopi ... 7&start=20

(Scroll down to the last couple posts on page 3)

What I had previously read of Art posting, he had mentioned just completely grinding off the KDX stud and just using the KX bolt, but I'll have to check the KDX H series and see how it looks in comparison to the photos here which leave a good chunk of metal that can be faced and bored/tapped nicely for a TimeSert insert.


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***Always run a brake snake type pedal restraint cable or leash to limit the amount of bending that the brake pedal can undergo in a crash when using aluminum brake pedals. Forged aluminum and high quality billet aluminum will be stronger and more forgiving than the cheap alloys and cheap cast generic pedals***

Billet aluminum proper enduro style kickstands:

Trail Tech billet aluminum frame-mount enduro style kickstands vs the klunky heavy root/brush catching stock kickstand:

2004 KX250/RM250 is a popular application Trail Tech Billet kickstand to modify the mounting bracket of, but at least two people have used an early 2000's YZ125 version which definitely looks to be closer to fitting the KDX H-series frames with less modifications needed.
These save weight, as well as being an actual functional enduro kickstand, meaning they swing up high out of the way, vs the stock kickstand which swings up parallel to the ground, and can lend itself to catching on brush or roots on get-offs on steep challenging hill climbs, to where gravity slides the bike back to hook the kickstand fully into the roots/brush and require a serious amount of effort or a second person to help lift/drag the bike uphill to get it freed from the tangle. This style also is far less likely to fling itself down when landing jumps or drops. I believe the 2003 YZ125 version may be the ticket, but there's also a YZ125/YZ250 version overlapping the YZ-125-only Trail Tech years.

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Clutch and Clutch Release upgrades:

'92-'93 KX125 clutch release arm is longer by 8mm or 10mm if I recall, giving you more leverage against the clutch springs, resulting in a lighter lever feel. Some consider converting to a hydraulic clutch to make the clutch easier, but this leverage alteration or extension is really where the gains are to be had. Hydraulic master cylinder vs slave cylinder bore diameters can be altered to do the same thing using the stock KDX clutch release arm, but a longer arm is really the correct way to do this. Hydraulic is higher maintenance, and really only makes it an easier pull by a very slight margin due to less friction of hydraulic fluid vs cable actuation. Disc brakes are hydraulic due to the drastically increased force required of brakes vs clutch release mechanisms, and the length of the lever arms and lubrication of parts that would be required to run cable actuated disc calipers.
I find the "Stiffer" 1997-2006 KDX clutch springs to still be quite easy to pull, and for me, I plan to do this mod so that I can use uprated aftermarket EBC, Barnett, or Hinson heavier clutch springs to prevent clutch slippage and give faster engagement out of corners/shifts and when disengaging the clutch release, so that I can get more power to the ground quickly. MoonStomper has cited that with his bike mods and the EBC springs, his bike felt noticeably faster when getting off the clutch lever. I'll be playing around with different KDX220 heads and different ported cylinders, Pro Circuit Platinum 2 pipes, and Lectron Billetron Pro Series carb + RB PWK35 Air Striker 36mm bored carb, and hopefully the upcoming SmartCarb SC2 35 KDX carb they're working on designing.



Additionally, since the '92-'93 KX125 clutch release arms are nearly impossible to find used and are NLA new, you can just cut the KDX arm and weld in an extension of 8mm or 10mm to lengthen the release arm. Use a slightly angled piece, as lengthening the arm will also put the cable connection point further away, requiring a slight bit longer cable or having the adjusters fully bottomed.
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Clutch cable upgrade:
Per Art Simmoneau, a 2007 CRF250 clutch cable OEM Honda is an upgrade over the stock KDX clutch cable, and has a metal elbow with a teflon liner sleeve in it on the engine case side.
I've picked up a Motion Pro T3 SlideLight version for 2007 CRF250X models, which is their high end premium cable offering with a smoother sliding action. An even better upgrade.

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1-finger hydraulic clutch retrofit:
Darryl Glen, I believe the guy on here who posted the YouTube video of the ART Pistons manufactured KDX220 piston comparison to show why it is a poor design vs the '86-'06 KDX200 piston made by SK, came up with this.
For serious hard enduro work and one-finger clutch operation, he extended his clutch release arm 8mm over stock (the max for this hydraulic setup), and swapped out the cable clutch setup for a one-finger hydraulic setup made by Clake in Austrailia, the Clake OneLight. I'm not sure if that's also the manufacturer of the slave cylinder retrofit that hooks to a cable clutch actuator arm, but he truly has a 1-finger hydraulic clutch setup now, which is the ultimate. https://www.clake.com.au/onelightclutch/
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Clutch Friction Disc upgrade:
Jeff Fredette and others have found that using Honda XR400R/CBR900RR/late XR250R clutch friction discs fit the KDX clutch basket exactly the same as OEM, but have 30%-40% more friction material surface area. Jeff Fredette uses the Made In Japan Vesrah brand VC-173 kits (contains 6 discs, he sells as a set of 7 to re-use the KDX clutch judder spring assembly, or he will sell a set of 8 if you are doing away with the clutch judder spring and running an extra clutch plate. The VC-175 Vesrah kit comes with 7 friction discs. The discs are the same when bought through Vesrah (Honda part numbers are slightly different for the two applications early XR250 / XR350R vs late XR250R/all XR400R), but the Vesrah individual friction disc part numbers are identical and have more surface area.

Photo of the OEM KDX (EBC) sized friction discs laid over the Vesrah Honda XR350R/XR400R plates that Fredette recommends. Fredette sells them in the correct quantity for the KDX, 8 or 9, whereas you'd have to buy a street bike kit to get a full 8, a part # which I don't have handy but you can find via spending a fair bit of time searching on the Vesrah web site for the individual plate number used in the vc-173 and vc-175 kits and then pulling up a list of all cork friction discs and then searching for the individual friction disc part number, the kit part number varies depending on quantity for the application.
The judder spring causes a bit of clutch drag especially when the engine is warmed up due to hot clutch swell of the friction linings, but allows smoother engagement, so I've gathered (I have ywt to try it out with this removed/swapped for an extra disc). Running an extra Honda style friction disc and deleting the judder spring will give you more friction discs for added engagement holding power, but will reportedly give more instant engagement that could be seen as jerky.
The OEM KDX steel clutch plates are used, not the Honda versions. The Honda friction discs are same o.d. but a larger i.d. but still fit in the KDX basket and still mate perfectly against the KDX steel plates as the plates are already a larger I.D. I'd suggest new steel plates or else a very extensive lapping of them on a surface plate with 120 grit or 220 grit emory cloth sheets (I use rectangular floor sander sheets for doing 4-cylinder 4-stroke bike & VW TDI heads).


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From Art himself, the KDX hybrid builder and site member who inspired all of this, and came up with the majority of the upgrade tricks above:

"You can also adapt the KX throttle assembly to the KDX by either buying a new cable, or filing down the ends of the lead barrel to fit the KDX cable into the KX throttle. This gives you a quick turn throttle, if you use the KX cable you need to slightly file down the end of the KX threaded portion of the throttle to gain freeplay. I've been using that for years. My KDX has evolved over the last 4 yrs from a basket case old abused KDX 220 to cross breeding with a box of left over KX and KX250F conglomeration of parts to a hybrid with a fully modded KDX hybrid, using a completely cryrogenically hardened bottom end and completely polished gear set and clutch and shifter internals, to a top end that was nikasil plated then sent to Fredette for his port work to give me more top end pull on the 220, & head milled. Fitted with a new Keihin PWK 35mm Air Striker carb with Moto Tassanari VForce3 reed block. JD Jetting triple taper needle, spot on jetting. Loudmouth air filter system, Pro Circuit Platinum 2 pipe fitted to an 03 KX 250 Pro Circuit 304 silencer. Adding a Wiseco clutch basket and 40 percent larger GPI radiators protected by MSR aluminum radiator guards. Carbon fiber frame guards custom built chain guard, KX250F brakes, 07 KX250F Showa forks and clamps and an 03 RM 250 rear shock with high and low speed adjustment. Both revalved and resprung. Pivot Pegs wider platform pegs. Taller Guts brand softer KX seat foam and Saddleman seat cover. There's more to the build, but that's the jist of it."

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Carb/Intake & reed cage upgrades:
Lectron Billetron Pro Series carb + Moto Tassinari VForce4 or VForce3 reed cage or Boyesen RAD Valve reed cage + intake is currently the best aftermarket carb upgrade available. SmartCarb are working on developing a KDX-inspired SmartCarb SC2 35 metering rod carb specifically because they receive at least 1 request per week (sometimes 1 per day) of customers wanting to fit a SmartCarb SC2 36 to their KDX, but the SC2 36 absolutely does not fit the H-Series KDX frames without extensive cutting and modifying/welding on the frame, so in other words, not really worth it, although they report that they have a few customers with KDX-engine / KX125-chassis hybrids running the SmartCarbs with great success, as the KX frames offer a bit more clearance in the shock crossmember area especially due to running a shock that's probably around an inch taller than the KDX's but in a similar Kawasaki perimeter frame.

A well jetted genuine Keihin PWK35 Air Striker is a great upgrade to a worn out stock carb or a smaller PWK33 KDX220R carb. Jetting is everything, and running a #5.5 slide up through a #7 slide along with the proper needle and proper jetting is CRITICAL to performance gains. JD Jetting sells these carbs and their own well developed triple taper needles that are quite popular. The JD Red needle is the one most KDX'ers use. KTM 200 owners use the inspiration for it, a couple different triple taper Suzuki RM250 Keihin needles.
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great write up,thanks for taking the time, the clake uses the magura slave cylinder

The last generation Honda CR125R/CR250R 2-strokes use the exact same brake levers as the '95-'06 KDX, when you're shopping for ASV aftermarket levers, or the slightly more affordable AS3 Performance aftermarket levers are available in green have to order the Honda kit contact them specially to get the green clutch lever and a replacement green KX brake lever to fit to the base, or just buy the crash replacement lever only separately. I'm not sure about the clutch levers, as the aftermarket lever companies use their own clutch lever perch across all models when going with their deluxe lever sets, but I believe the OEM clutch levers are the same vs the last generation ('97-'06?) CR125/CR250.

Also, Yamaha used Titanium foot pegs and shock springs on *some*, not all, 2000's & 2010's models. Their shock springs had a reputation for cracking, however, as did the first several years of the titanium foot pegs. RCS aka Renton Coil Spring sell high quality titanium springs, but the cost is so high that it's hard to swallow, luckily I got a used one for the RM 125 shock which I'm going to be running soon.

Diverse Spring now sell lightweight Chrome Silicon Steel aftermarket shock springs for Showa and KYB in KX, YZ, RM etc sizes and no longer sell titanium springs, as this alloy of steel comes *close enough* to the weight of the titanium springs at a quarter of the cost. Some people really prefer the feel of a titanium spring, however. They often confuse suspension tuners who are unfamiliar with their characteristics, however.



The Yamaha titanium pegs are easy to spot just by the color and finish of the metal, and they can be ground down to fit the KDX. They are basically the same shape but with some extra metal up against the frame pad that needs removed, and a tube sticking out the side of the pivot. They actually have removable bolt-on frame mounts which would be a nice idea to weld threaded sleeves onto the KDX H-series frame to use in order to have replaceable foot peg mounts like the E-Series KDX and the KX500 I believe. The peg pin mounting holes on the KDX frame are something that can get worn out with time... Just like the brake pedal pivot stud that's welded to the frame.

The part numbers for the titanium Yamaha left and right foot pegs are:
5XE-27411-00-00 and 5XE-27421-00-00

This post basically details about what it takes to make them fit, very similar, this is for KX500 but that has the same interchange on foot pegs as the KDX200E, KDX200H/220R, and KDX 250:
http://www.oem-cycle.com/forum/viewtopi ... 1423#p7230

Yamaha pegs had a pretty long interchange, like 1997 or 1998 through 2015 on most 2-stroke and 4-stroke models of YZ. Converting to the Yamaha YZ bolt-on frame mounts isn't a bad idea, you can buy brand new Fastway pegs in billet aluminum to fit the YZ, which I would trust more than the YZ OEM titanium pegs. Those Fastway aluminum pegs might also be a good candidate for converting to the more minimalist KDX / KX500 / '96 & earlier KX125/250 peg style?

KLX300 & KLX250 suspension links are 117mm vs the KDX's 112.5mm, and *some* are a nicer stainless steel bushed thicker aluminum version vs the KDX & other KLX steel versions. They are not SIGNIFICANTLY lighter in weight, although they are lighter, and they also require the wider bolts off of the KLX with the aluminum variety suspension link pull rods, when running on a KDX.

The wider versions actually share *almost* the same rocker linkage bolt width, slightly narrower actually, as the KX500, AND... the KX500 swingarm pivot axle/bolt is the same part number as the E-Series and H-Series KDX. Pictured are titanium KX500 swingarm pivot bolts and suspension linkage rocker bolts from RJP / Factory Image Racing. So of course I had to buy the KLX aluminum 117mm suspension links (vs steel 117mm) to run the titanium KX500 rocker linkage bolts! Those are the biggest 4 bolts on the bike, and so the heaviest 4 bolts on the bike!

The 117mm links will lower the KDX H-series around 22mm / 7/8", which I found useful for running a 1" taller '01-'04 (or 94-00) RM125 Showa shock or similar KYB shock from a KX, in order to level out the ride height closer to stock. The 1" taller shocks will raise the rear rode height about 2.4", so I'm also using a NiceCNC or similar sealhead "30mm lowering spacer" which is 10mm thick and will lower a KDX about 7/8" or 1" as well, due to the slightly different rocker ratio on the KDX suspension.

This will help match the much taller 11.4" travel '97-'98 Suzuki RM125 forks I'll be swapping, although a 7mm sealhead spacer may be more appropriate.
The 117mm links alone should match the MX shocks to a 12" travel fork swap height.

Update -
Chopperpilot tipped me off that the '93-'96 KLX650R actually came with a 115mm version of those stainless steel bushed thicker aluminum version suspension linkage pull rods!!!! As I'd had a slight suspicion/fear that 117mm (from stock 112.5mm) + the 10mm sealhead lowering spacer might potentially be just a bit too much lowering of the 1" taller shock (2.3" ride height increase minus about 1.8" between the longer links and the reduced legth shock via sealhead lowering spacer,), 115mm aluminum links will give me the option of a taller back end or also the ability to run less preload on the shock spring for more rear sag for better bump compliance... I'll be ordering up a used pair of these

*I'm beginning to go back and edit the posts with adding photos to them for your viewing pleasure as well as clarity on the parts involved.


Here you can see where a good chunk of my paychecks went after my suspension linkage rebuild - which sent me down a DEEEEEEEPPPP rabbit hole vortex after holding the big solid suspension linkage bolts and solid swingarm pivot bolt in my hand and thinking "WOW, these things are REALLY HEAVY!"

Well... Titanium is 45% lighter by volume than steel

Enter the KX500 RJP Motorcycles / Race Tech Titanium Black Friday 20% off sale / Titan Classics ti brake caliper pistons/pins/bleeders etc hardware kits / Mettec / Ti64 / etc frenzy of buying darn near every substantial fastener on the bike in Titanium (or aluminum where greater strength wasn't necessary - Tubliss rim locks, kicker shaft nut, etc)....

I was thinking about building a KX125 / 220R hybrid solely to save weight (they're the same geometry '94-'02 as a KDX), as well as STILL considering building a very potent woods ported woods setup big bore high compression 110 octane burning '96-'97 or '00 KX125 "KDX134," or '03 KX125 "KDX144" with 2010's KX250F Showa SFF coil soring forks, as the ULTIMATE lightweight woods bike, but the torque of the 220 would be impossible to match, and a hybrid really only saves 5lbs or so off a KDX's weight, mostly from slightly smaller fuel tank and thinner seat + aluminum seat subframe that's also shorter in the rear (less frame under the end of the fender).
I'm looking to shave additional 7lbs off of what a KX125/KDX hybrid weighs with the added aluminum parts and all the titanium and a few aluminum fasteners etc... Around 15.5lbs total, but then adding weight back on with skid plate, radiator guards, a bigger charging system, and the fat tube 49mm '98 RM125 Showa Twin Chamber right side up forks + larger/longer '01-'04 RM125 Showa shock...

I'm STILL considering the afformentioned 134cc or 144cc woods valved high compression 18" wheel setup KX125's for the future, but my love for the '97 KDX220R/96-98 KX125 stylings and purple '96 shrouds and graphics really led me to want to lighten up the KDX vs building a 125/220R hybrid....

THANK YOU for all the information and pictures!

Great stuff Chuck! Thanks for taking the time to share it with the membership.

Chuck78 wrote: 10:37 am Jun 24 2024 KLX300 & KLX250 suspension links are 117mm vs the KDX's 112.5mm, and *some* are a nicer stainless steel bushed thicker aluminum version vs the KDX & other KLX steel versions. They are not significantly lighter in weight although they are lighter, and they also require the wider bolts off of the KLX if they are the aluminum variety, when running on a KDX.

The wider versions actually share the same rocker linkage bolt size, slightly narrower actually, as the KX500, AND... the KX500 swingarm pivot axle/bolt is the same part number as the E-Series and H-Series KDX. Pictured our titanium KX500 swingarm pivot bolts and suspension linkage rocker bolts from RJP / Factory Image Racing.

The 117mm links will lower the KDX H-series around 22mm / 7/8", which I found useful for running a 1" taller '01-'04 (or 94-00) RM125 showa shock or similar KYB shock from a KX, in order to level out the ride height closer to stock. The 1" taller shocks will raise the rear rode height about 2.4", so I'm also using a NiceCNC or similar sealhead "30mm lowering spacer" which is 10mm thick and will lower a KDX about 7/8" or 1" as well, due to the slightly different rocker ratio on the KDX suspension.

This will help match the taller 11.4" travel '97-'98 Suzuki RM125 forks I'll be swapping, although a 7mm sealhead spacer may be more appropriate.
The 117mm links alone should match the MX shocks to a 12" travel fork swap height.

Another option here is the links off of a KLX650R (which is a pretty rare bike especially in the US). I lowered my KLX650R using 119.5 links off of (? I forget), but the factory KLX650R links are the bushed aluminum ones at 115 length, so right in between the KDX (112.5) and KLX300 (117).
There are two versions of KLX650, one is the street legal version with electric start, battery, steel swing arm and links (longer on both too), but the KLX650R was a kickstart only version, with nicer bits (aluminum swing arm, links, better rear shock). The 650R forks have compression adjustment and are a touch longer. Maybe I should take a look at the kicker on the 650R.......

Chopperpilot wrote: 01:15 pm Jun 25 2024

Chuck78 wrote: 10:37 am Jun 24 2024 KLX300 & KLX250 suspension links are 117mm vs the KDX's 112.5mm, and *some* are a nicer stainless steel bushed thicker aluminum version vs the KDX & other KLX steel versions. They are not SIGNIFICANTLY lighter in weight, although they are lighter, and they also require the wider bolts off of the KLX with the aluminum variety suspension link pull rods, when running on a KDX.

The wider versions actually share *almost* the same rocker linkage bolt width, slightly narrower actually, as the KX500, AND... the KX500 swingarm pivot axle/bolt is the same part number as the E-Series and H-Series KDX. Pictured are titanium KX500 swingarm pivot bolts and suspension linkage rocker bolts from RJP / Factory Image Racing. So of course I had to buy the KLX aluminum 117mm suspension links (vs steel 117mm) to run the titanium KX500 rocker linkage bolts! Those are the biggest 4 bolts on the bike, and so the heaviest 4 bolts on the bike!

The 117mm links will lower the KDX H-series around 22mm / 7/8", which I found useful for running a 1" taller '01-'04 (or 94-00) RM125 Showa shock or similar KYB shock from a KX, in order to level out the ride height closer to stock. The 1" taller shocks will raise the rear rode height about 2.4", so I'm also using a NiceCNC or similar sealhead "30mm lowering spacer" which is 10mm thick and will lower a KDX about 7/8" or 1" as well, due to the slightly different rocker ratio on the KDX suspension.

This will help match the taller 11.4" travel '97-'98 Suzuki RM125 forks I'll be swapping, although a 7mm sealhead spacer may be more appropriate.
The 117mm links alone should match the MX shocks to a 12" travel fork swap height.

Another option here is the links off of a KLX650R (which is a pretty rare bike especially in the US). I lowered my KLX650R using 119.5 links off of (? I forget), but the factory KLX650R links are the bushed aluminum ones at 115 length, so right in between the KDX (112.5) and KLX300 (117).
There are two versions of KLX650, one is the street legal version with electric start, battery, steel swing arm and links (longer on both too), but the KLX650R was a kickstart only version, with nicer bits (aluminum swing arm, links, better rear shock). The 650R forks have compression adjustment and are a touch longer. Maybe I should take a look at the kicker on the 650R.......

Hey...THANKS!!!!!! I HAD NO IDEA!!!!

As you might have noticed, I said the 1" longer shock (= about 2.3" taller ride height iirc) minus about 7/8" or 22mm from the 117mm KLX300 links minus about another 7/8" or 22mm from the 10mm sealhead spacer might be just a touch too low, and a 7mm sealhead spacer might perhaps be best (custom...).

Well... If I was correct about that approximate swingarm leverage ratio calculation and lowering effects of the sealhead spacer, then 115mm would work out darn near PERFECT!!!
That's going to more closely preserve the stock progressive linkage rate, and if anything, will allow me to run less preload on the rear shock spring for a little more sag for more choppy rugged terrain bump compliance...
They are scarce though, only two pairs on eBay and none available new or NOS.... 46102-1348 is the Kawasaki part #.
I'll try and pick up a pair to have as a tuning tool, as it can't hurt!

Yeah, the KLX650 is a hard bike to get parts for, but kind of a cool one off thing that no one recognizes. I think 93-96 was the only years they were available here. Up through 2002 or so in Germany and Australia though I believe. It really is kind of a big 4 stroke version of the KDX, the 650Rs had a good shock and fork on them. The Front wheel will fit on the KDX (they use different size bolts to hold on the rotor, but that's the only difference). It's a bit harder to kickstart than the KDX!

Is there any particular advantage to running a 1" longer shock? or is it a case of that's the closest sized Showa (shock with adjustable HS compression and rebound) that'll fit and you're working around that?

Chopperpilot wrote: 10:53 pm Jun 25 2024 Is there any particular advantage to running a 1" longer shock? or is it a case of that's the closest sized Showa (shock with adjustable HS compression and rebound) that'll fit and you're working around that?

Ideally, an upgrade shock would be around 8mm or 12mm longer than stock (vs the '97-'00 RM125/250 & '01-'04 RM125 shocks at around 25mm-26mm longer than stock), in order to better match the popular fork upgrades' height, as to not have to internally lower those forks which often requires shorter springs....

The larger diameter shocks have more oil volume in order to keep the oil running cooler, as well as more nitrogen volume, not to mention the larger piston area which will also help with keeping things plush and keeping the oil from having any chance of cavitation as well as keeping it running cooler. Then there's the obvious benefit of having a more advanced compression adjuster set up with low speed and "high speed" compression adjusters independently, although it's more like a low speed and a mid-speed compression adjuster, not necessarily high speed, but it's referred to as low speed vs high speed clickers generally.

The reservoir mounting position / configuration is highly dependent on what shocks will fit our bikes, which is why these RM shocks are the best or most popular swap / fit, and Showa CRF250 shocks do not at all, nor DRZ400/KLX400 shocks, although they are all fairly identical in operation. 2005+ KXF & RMZ Showa shocks are nearly identical, but they are yet another 1" or so longer with their extended clevis mounts, which look like they could perhaps be shortened up and redrilled to nearly the '97-'00 / '01-'04 RM125 configuration/length. The '94-'96 RM125/250 shocks also should be identical, but only 46mm piston o.d. & body i.d., vs the KDX's @ 44mm iirc, & the '97+ Showa @ 50mm piston o.d.

I may likely try an '08-'16-ish Showa KX250F shock (EDIT - now looking at a very similar 2010-2014 Suzuki RMZ250 version due to better compression adjuster positioning in relation to the KDX retrofit fitment with the adjuster on the right instead of left by the side cover plastics) + shortened clevis, as the Lainer Suspension brand aftermarket upgrade compression adjuster assemblies for these shocks don't advertise the '01-'04/'05-'08 RM or '06-'07 KX250F versions, & I feel they will be a good benefit to my rear suspension swap, as I'll get both a true high speed compression adjustment vs the mid speed & low speed Showa shocks actually offer as stock (despite their labeling/claims), as well as better assistance in tuning a shock for our bikes for woods riding, which was a shock intended for a different linkage setup and different weight bike...



https://lainersuspensionusa.com/shop/sh ... a-crf-kxf/

The Lainer adjusters advertise more broad range of adjustability then stock, & have an optional "enduro stack."

When I spoke to the tech guy at Lainer Thursday, he said he didn't believe their "older Showa" adjuster would woek for the '01-'04 Showa RM shocks, due to different depth in the adjuster housing portion of the shock body, but I suppose I'll find out in the coming weeks in person before I fork over $80-$150 for an RMZ250 Showa! They have fatter shafts (& 05-08 RM 2-strokes) vs the '04 & older as well as the Showa KX250F years 2008-2019-ish.
The larger shafts aren't a strength upgrade, they were done to be able to bore the shaft out larger for the rebound adjuster to be able to flow more shock oil faster when needed, without compromising design strength. It's a minimal amount of benefit obviously, as the Kawasaki KX250F (& presumably KX450F) kept the smaller diameter shafts through the entire run.