KX125/220 hybrid vs upgraded suspension on 95-06 KDX

[Chuck78]

I'm not one to leave much of anything stock, but what brings me here again is the curiosity of what a KDX/KX125 hybrid's ride feel is like vs a '95-'06 KDX with upgraded suspension.

I'm really wondering if a KDX/KX125 hybrid with a 3.0 gallon or 3.4 gallon oversized tank, filled to the brim, will feel less top heavy than a perimeter frame 1995+ KDX with stock 2.9 gallon frame or Clarke Mfg 3.4 gallon tank and taller KX or RM125 suspension front and rear.
That is the big motivating factor that would make me build a hybrid.
Otherwise I'll just be quite content with my upgrades on the shelf (swap soon!) to a 1"+ taller ride height '98 RM125 fork and '01-'04 RM125 shock internally lowered with KLX300 suspension dog bone links (will level out the ride height to match these forks), and adding a lot of titanium fasteners, linkage bolts, swingarm pivot bolt, and axles to reduce weight.
On less than 60 mile rides, I can just run my KDX's Clarke oversized tank with only 2.5 gallons in it in order to keep the weight lower (I run metering rod carbs - Lectron etc vs Keihin PWK, which extends fuel range 20%-25%).

Hoping to get some real world comparisons aside from just people saying that the slender 125 feels a lot more slender and agile. I'm not looking for desert racing stability or motocross handling, specifically looking for a bike that is even better at the gnarly tight woods technical terrain as well as 3rd or 4th gear fast flowing woods trails, AND is easier to pick up when dropped.

I can knock 11 or 13lbs off my bike with titanium fasteners. The 95-06 KDX frame really can't be that much weight difference than a KX 125... The engine and aftermarket pipe for a 220 weighs about 14lbs more than a KX125 engine and aftermarket pipe, which did have me heavily considering a 144cc build, but I love the lugability and rev-out of a modded 220 engine, it's truly like a downsized 300 with more top end.

I'm still leaning towards just keeping the two that I have and dropping a lot of money on titanium fasteners, as well as running a Clarke oversized tank not filled to capacity (I believe it does carry a little bit more fuel down low, not just added volume up top).

I'd appreciate some real world comparisons if you guys can chime in with your thoughts!

[Chuck78]

I was just drooling over the new TM 2-stroke EN 144 woods bikes as well as the Beta 200RR Race Edition model, but to be honest I can't justify spending that kind of money when the 220 engine does so well coupled with modified suspension. That plus the fact that the Beta really should have a 6-speed transmission, it's narrow close range hearing limits it's top speed, although I saw them go over 60, I can see that being a drag once in a while. The 220 is just such an awesome engine all around with a modified head and carb upgrade.

[Chuck78]

The KDX has a rake angle of 26.5° which is great for gnarly tight woods riding. The 96-98 KX125 is 26°, even steeper, which will turn even quicker. Some KX125/250 chassis from 99-08 have 26° up to 27.5° rake. The 27.5° rake would be the ones I would avoid.

Personally, the 96-98 chassis would be the most preferred overall, due to 26° rake, being a bit more compact vs later KX125 frames (I'm speculating here), & the big one - having purple plastics and '96 shroud graphics available for it... Although the purple '96 styke shroud graphics are available for the 2003-2008 KX125, & a purple seat cover is no problem to get made up...

The 03-08 KX125 & KX250 share basically the same frame although the rake angle is a half degree different than the engine mounting is different. Most if not all of these 96-98/99-02/03-07 or 08 models share the same oversized fuel tank interchange and exact same shrouds/plastics etc. For me, keeping the bike compact and slender would be a big consideration, so frame smaller frame size is definitely a consideration. The 1996 KX model line brochure shows some definite differences in the KX125 vs KX250 chassis specifications at least.

Ultimately I'm just wondering if it is going to be a significantly noticeable "perceived weight difference" in handling for tight woods riding going to a 125/220 hybrid vs a modded 220 with taller '98 RM125 fork & reworked/7mm lowered '01 RM125 shock + aluminum KLX300R suspension linkage dogbones, and say just running the KDX fuel tank with the amount of gas that the stock KX125 2.25 gallons tank holds vs 2.9 or 3.4 gallons... The Lectron carbs really increase fuel efficiency drastically, and I never will hit reserve when riding with others anymore since shelving the venerable go-to PWK carbs.

Picking up the KDX after dropping in precarious situations on technical terrain or dragging it out of quicksand mud bog type scenarios biggest consideration here. The KDX H-series definitely feel very top-heavy compared to center spine type bikes like the E Series or most European Enduro models. That's the ONLY real complaint that I can't get over. I need to ride a nicely modded E-Series I suppose, as sticking a 220 engine into one of those with perhaps a DRZ400E shock and one of my spare '98 RM125 forks would perhaps fix the higher center of gravity issues, but then I have less pipe availability, but I could probably rework things to fit a 95-06 pipe into an 89-94 frame.... Makes me wonder how a KDX engine would fit into an '88-'89 KX125 frame as well!

[bufftester]

I have a KDX220 Hybrid built on a 2001 KX125 frame with 2001 KX250 forks. I had my KDX from day one for 10 years and loved it. A wreck that tweaked the back half of the frame led me to do a hybrid build. The hybrid definitely "feels" lighter, though it weighs nearly the same. The rake on that year is .5 degrees steeper than the 220 frame which in theory should make it turn sharper, but the wheelbase is half an inch longer on the 125 so on the trail it feels a bit longer than the KDX and doesn't turn quite a s tight. Part of that may be because I haven't modified my steering stops which would give me a little more arc on the fork swing, but for what I ride it's not really an issue. The easiest way to describe it is that on the KDX I always felt like I was sitting "IN" the bike, and the 125 frame feels like you're sitting "ON" the bike. I prefer it as it really coaxes you to stand more (the seat on the hybrid is thin and HARD, sitting for any length of time gets a bit uncomfortable, but that would be expected from a MX frame). Honestly you could spend the money on the suspension of the KDX and get nearly the same performance, but for me at least the hybrid just feels better. Its an entirely subjective thing. My son has a 98 RMX250 which is a lot like what a race KDX would look like, and he prefers the ergonomics of it, but he is also 5 inches taller than me so the bike isn't really set up for him. The hybrid doesn't really feel top heavy, but then I never really felt like the KDX was either. In the flowy stuff the slightly longer KX frame really shines, in the super tight woods the KDX really shined for me. At the end of the day the only question that matters is given the choice would I go with a KDX again or with the Hybrid, and for me the answer is Hybrid
Pics for because...

[Chuck78]

Seeing your second and third photos back to back definitely illustrates why the KDX might feel more top heavy than a KX125 hybrid... compare where the additional fuel weight is carried... ALL UP HIGHER!
The fact that a fair bit of the fuel tank sits under the KX125 seat, versus on the KDX with the fuel tank sloping up dramatically and having all of the additional volume up high... I think the fuel tank sits lower overall on the 125 as well, especially considering how one of the hybrid builds that I read of had issues with the KX 125 aftermarket desert tank's petcock hitting the KDX 220's cylinder head.
It is now even more apparent why the H series KDX has issues fitting a standard electron carb, smart carb, etc... That giant sofa of a seat! The shock crossmember sits much closer to the carburetor in order to make room for the very thick cushioned comfortable seat...

I still have a third 220 engine and only two bikes, and it is nice having a spare, but it may still continue to tempt me! I think a woods ported 144cc big bore with woods valving and 18" rim may be the better answer as far as shedding weight for a lighter feel and a bike that's easier to pick up. But a modded 220 engine is just absolutely brilliant in the gnarly nasty terrain...

Honestly I think a 220 H-series engine in an E-Series KDX200 with 1996+ Showa Twin Chamber forks and shock or even stock shock with RaceTech Gold Valves and identical looking Showa 49mm conventional forks but open chamber DRZ400 versions lowered 1" internally might perhaps make a much lighter feeling ultimate woods machine... This is a hybrid of sorts as well... The center spine E-Series frame allows the gas tank to carry a significant amount of the fuel weight much lower than an H-series, and those 88-89 KX derived side covers look too cool... Maybe I'll also keep an eye out for an E-Series roller with bad fork and no engine... And adapt H-series radiators and engine to it (the engine is basically a direct swap).

[Chuck78]

I definitely feel the difference of fuel tank positioning and size/capacity would make the KX chassis feel lighter, but I'll see what blowing some paychecks on Titanium fasteners on the KDX will do... LoL
I was blown away with how heavy the swing arm pivot bolt and three big rocker arm linkage bolts weighed on my last suspension bearing replacement a few months back. So I tracked down KX500 titanium replacements for those, they are absolute feathers compared to the hefty stockers. I'll be running a titanium rear axle as well, although I have yet to find a good replacement for the 96-99 RM125/250 fork's axle (I've actually found that a '99-'03 KX125/250 axle is a bit more preferred along with a '99-'05 KX/KXF (& '04-'06 RMZ) wheel to retain the Kawasaki floating rotors.

Originally I intended to focus on titanium fasteners on the higher upper portions of the bike, as weight up high makes the bike feel heavier to pick up when dropped, but then I later realized that it was every bit as critical to shed 4-5lbs down low with just replacing these 5 substantially heavy chunks of steel!
Apparently the weight weenies even use aluminum bolts for the plastic bodywork...lighter and cheaper than titanium!
I'll be running titanium bolts for the handlebar clamps/risers and all 8 triple clamp bolts, as well as doing a VStrom DL1000 aluminum steering stem swap for my RM125 triples (same stem but too short, VStrom is just barely long enough vs short RM stem). The aluminum steering stem and Ti bolts up top will help. I have to resist the urge however to NOT spend $13 x 8 on purple titanium M8x45 triple clamp volts vs plain ti color for $4-$5 each x8...lol
Also got titanium brake kits with ti pistons, pins, banjo bolts, bleeder screws etc... Titan Classics even sells titanium KDX head studs & nuts!
Getting an order in for engine mount bolts in Ti as well shortly
The fat 49mm conventional 98 RM125 Showa Twin Chamber forks will add some weight as well as rotor guards, skid plate, handlebar bag etc... So trying to shed as much as possible will be of great benefit.
Heck now I'm even considering using a stock purple tank instead of my Clarke oversized, and using a KDX SR model oil injection tank of the variety that mounts off the left rear subframe behind the side plate, as an auxiliary fuel tank for long hauls, as this sits lower by far... Although that location is a nice spot to fabricate a holster for a 10" blade folding saw or even a longer fixed handle folding saw and sheath

[jakeslouw]

At the price of all the titanium, I'd rather just buy an Orange 300 TPi and get done with it.

[Chuck78]

At the price of all the titanium, I'd rather just buy an Orange 300 TPi and get done with it.

With myself not really caring about electric start, and with Lectron Billetron Pro Series and SmartCarb SC2 36 carbs being as good or better fueling performance than KTM fuel injection, I'll be a good $5,000-$5,600 ahead financially to just modify my 220, which is one heck of a great platform to start out with... The cost of a new bike doesn't equate to the added benefits of buying a new bike...


Plus, they dont make KTM's in 1996 green/purple evo/revo era graphics, which is 1,000x better than being on a pumpkin colored clone of everyone else
White or solid red alternatives aren't much better, and I'd rather not buy a pumpkin only to drop another $450 on all black plastics and fuel tank

[Chuck78]

At the price of all the titanium, I'd rather just buy an Orange 300 TPi and get done with it.

I will say though that if they made a TBI version of the Husqvarna TE150i TPI model, that would be one heck of a great all-white bike as long as you don't mind carrying a spare fuel pump and other electrical parts to the trailhead with you

Don't confuse me with an old geezer luddite who thinks all cars trucks and bikes should still be running points ignitions, but after having a wife who was formerly employed as the parts department manager at a European brands motorcycle dealership, fuel pumps fail on modern motorcycles a lot more frequently than you'd care to know, & AAA roadside assistance doesn't service the 5 Miles of Hell trail, Hatfield McCoy trails, etc...

[Chuck78]

I'll also add that a Father/son riding team have a 2017 carb KTM 300 (Dad) with a Lectron Billetron Pro Series carb & a 2022 KTM 300 XC TBI, & the carb'd 2017 with the Lectron Billetron Pro Series reportedly has better top end power as well as every bitvas good of low end power and response... Similar reports from SmartCarb SC2 users on KTM 300's... Metering rod carbs are the absolute best once dialed in perfectly, if you take the time to dial them in or swap and tune different SmartCarb metering rods...

[jakeslouw]

I will say though that if they made a TBI version of the Husqvarna TE150i TPI model, that would be one heck of a great all-white bike as long as you don't mind carrying a spare fuel pump and other electrical parts to the trailhead with you

I rode a TE150 TPI the other day: If I say I was gobsmacked it would be an understatement.

Dual map switch on the handlebars, go from mild to wild immediately. Light, torquey, yet will rev like a 125 on the fast map. Lovely suspension and a full size bike on top of it. Didn't even feel as if I needed to do much to accommodate my 105kg except play with the clickers.
Just a pity they are still attracting very high resale over here, otherwise I'd have sold my Chinese trail 250 and my pile of KDX bits a while ago and have parked one in the shed. Oh yes, and my wife loves them.

To go back to suspension: I'd say a KDX200/220 with a SS109s CDI, an FMF Gnarly, in a tweaked 99-02 KX125 frame with revalved suspension would be the dogs bollocks. That sort of where I'm going.

[Chuck78]

I rode a TE150 TPI the other day: If I say I was gobsmacked it would be an understatement.

To go back to suspension: I'd say a KDX200/220 with a SS109s CDI, an FMF Gnarly, in a tweaked 99-02 KX125 frame with revalved suspension would be the dogs bollocks. That sort of where I'm going.

Yes, the modern 150's are absolutely AWESOME... FYI looking at the specs, the Husqvarna versions are slightly less extremely tall than the KTM versions, by a half inch iirc? I would be very reluctant to ride a KTM brand bike, and especially an orange KTM, but the 150 would be the biggest sway to do so... 300's are popular for their ease of rideability and monstrous and broad torque - you barely have to shift gears on singletrack as the engine pulls well across the whole power range. But not everyone actually needs that much power, and the slight added weight of the larger engine and chassis, not to mention the handling losses from a bigger crank/piston/rod + balance shaft - as the gyroscopic effect of that added mass makes the bikes have a greater tendency to resist change of direction, meaning the heavier the rotating mass inside the engine is, the more the bike wants to stay upright at times when you want to whip it over to the side in a turn etc... They feel less nimble. Also a fair bit heavier to pick up when dropped.

If I were to actually look at selling my venerable and ultra reliable old KDX or at least buying a new bike (not for $10K unless I win some sort of lottery!), I'd really have a hard look at a Beta 200RR Race Edition first and foremost, and I'd probably switch immediately to a SmartCarb SC2 36 for the added low throttle low rpm response and torque that the SmartCarbs give which even fuel injection cannot match (Smart Carb have patented the venturi shape that give this amazing response). Loving my KDX220 tremendously, I'd originally thought that a Beta 250RR Race Edition would be the bike to have, but the 200RR is lighter and the SmartCarb addition would boost the low end power more. That'd be a difficult machine to beat. Beta did have some issues with engine bearings wearing out prematurely in the late 2010's as well as wiring harness connector issues, but they've addressed those issues, and I really like the feel of their bikes and the chassis design/layout better than any other dirt bikes. Have to add all black plastics though as the blue and red doesn't do it for me... easy fix for cheap though!
The added weight of e-start on a bike is not really worth if for me though, but since the weight is down low, perhaps it won't make the bike feel any heavier on the trail to pick up? The fuel tank droops well down on the sides, so the center of gravity is far lower than an H-Series KDX, which really helps with a lighter feel, as would running a KX125 or Beta fuel capacity in the larger KDX gas tanks instead of topping off!

One last modern bike rant - TM's EN 144 2-stroke enduro bike is another absolutely brilliant one... Wow. TM are all hand built and absolutely incredibly designed very well thought out machines, and perhaps the best aluminum frames on the market... That'd be another very tempting model, IF I suddenly happened upon a large sum of money

[Chuck78]

This was a really interesting thought... The KDX seat is quite the sofa versus an uncomfortable modern bike seat or a KX125... and my neighbor buddy did comment to me that the KDX H-series seats are the absolute most comfortable bike seats he's ever sat on, even 20-30 year old original foam!
In other words, THAT'S A LOT OF FOAM! But foam is light, is it not? See this post that I dug up on ThumperTalk when reading about shear strength and anti-sieze with titanium fasteners and axles on bikes:

There was a bloke on here yrs ago from Italy. He built a really light weight CR125AF. He said the 2 biggest weight savers were the titanium shock spring and the Guts Phantom or Think LW seat foam.

The Guts Racing Phantom seat foams are a lot lighter than OEM, It's a huge weight saver, and the weight is higher up.

Very interesting... I wonder if they still make foam for our KDX seats?



From the manufacturer:

"Ultra-lightweight seat foam is not new to many factory top level pro riders. Many factory race teams have discovered that removing small amounts of weight at the highest point on a motorcycle has a great impact on the way that machine handles. The Phantom Ultra-Lite seat foam has shown outstanding durability and the closed cell design keeps it from soaking up water.

*While other companies have tried to make this foam available at a much higher price, GUTS Racing can now offer it as an affordable option.
*Used by more factory race teams world wide than any other brand.
*The Phantom foam has a slightly firmer feel than the stock foam."





I just emailed Guts asking about this. They do list our models in their product finder, along with several customization options. I'll just copy & paste:

"How can I get the Phantom Ultralite seat foam for my KDX seat? I see you have various options for 1995-2006 Kawasaki KDX seats, but the Phantom UltraLite is not displayed. Since you do so many different custom bump/rib/height options, I can only assume that these are all made to order?"

[KDXGarage]

Chuck78, the stock foam is really heavy compared to the super high dollar foam. The super lightweight foam probably is not for an all day ride.

[Chuck78]

In other weight reduction efforts, I've discovered Mettec has a really good variety of 6AL-4V Titanium bolts listed in their Marine section for cheap, but the parts in their bike-specific fitment sections are extremely pricey, and I thought Race Tech Titanium's prices on axles etc were a fortune!!!

I found them searching M10-1.25 x 105mm lower engine mount bolts. Best bang for the buck is to replace all the largest heaviest steel fasteners with titanium first, and all the fasteners higher up on the bike where the weight is felt the most - the handlebar mounts and perches/risers, triple clamp bolts, fork swap that retains al aluminum steering stem if possible, Guts Phantom Ultralite seat foam, etc...