KX front end put straight on the kdx?

[KR90]

Are there any years of KX125's or KX250's that would bolt right on to an '03 KDX? Not an MX'er, and i really like the suspension setup in the tight woods where i ride its just that i hate how far the forks go past the axle. I am always hitting them on rocks, roots, etc...

any advice greatly appreciated! Thank you.

[Smason25]

91 kx 250 bolt right on, Also 94-96 kx 500 triple clamps with 94-96 forks works as we'll

[sarrant]

If you really like the stock suspension setup, KLX300 forks would be the most similar to the KDX stock valving and spring rate, in an inverted (no underhang) configuration, and they do bolt straight up.

[KDXGarage]

...annnndddd, don't need to be internally shortened or pulled up in the clamps like Urkel's pants.

[gymer99]

I have a chance to pickup a complete front end off a 2004 kx 250 and would like to put it on my 2003 kdx 200 any ideas on how much of a problem fitting that up would be?

Thanks for any help

[6 Riders]

I have a chance to pickup a complete front end off a 2004 kx 250 and would like to put it on my 2003 kdx 200 any ideas on how much of a problem fitting that up would be?

Thanks for any help

You'll need to swap stems and use a spacer at the top triple clamp. The forks are [about] 1" longer than KDX forks, so moving them up in the clamp or have them lowered (ideal). You'll probably want to respring & revalve them for the type of riding you do also, KX forks are for motocross and don't tend to play well in the woods w/o valving mods.
Oh and don't forget the wheel, you'll need the KX wheel.

[KDXGarage]

stem swap required
forks are too long and need to be shortened internally or pulled up a good bit
fork clamps or legs will hit side of tank
KDX front wheel won't swap over
etc.

Please use the search function, as this has been covered for 10 years on this forum.

[turtle]

If you really like the stock suspension setup, KLX300 forks would be the most similar to the KDX stock valving and spring rate, in an inverted (no underhang) configuration, and they do bolt straight up.

I think this swap is the most straight forward. Had I know more, I might have pursued this avenue on mine instead of the KX. I think it would have been cheaper. I also think it would have suited my riding style just fine and I would have been just as happy with the result.

In any case I'm glad I did it. The underhang is a definite problem on the trails.

[Kdx kiwi]

I have just put a 01 KX125 front on my 97, just needed a new top bearing
And extended steering stops

[bored808]

I don't mean to jump on your thread but I have an opportunity to buy a front end from a 1992 kx250 for a good price. Is it a direct bolt on? Has anyone used the 1992 setup?
This is probably a stupid question but how much difference does it make?
I used to ride mid 90's cr125's when I was young and I loved them!

[KDXohio]

No it is not direct bolt on trust me I tried

[Rippin_RobMX]

KDX front wheel won't swap over

Why won't it work?

[KDXohio]

KDX axle has to be modified I believe to get the wheel to work

Easiest swap is the 90-91 kx125, 250 or klx swap and I think all years kx500 usd's work someone will correct me if im wrong

[Chuck78]

Reviving an old thread for info consolidation, but here's what I've learned.

KLX300R forks are the easiest swap, as they are valved similar (but better) to the stock KDX fork for woods, are the correct height without mods, and come with a decent spring rate for a lightweight woods rider at .37 or .38kg/mm. KDX wheel is a direct fit into these forks without any axle adapters. These are still the same cartridges and tube diameter as the stock KDX right side up "conventional" forks at 43mm, but they are significantly less flexy than the KDX forks due to being inverted. These are lacking the full external adjustment that the KX forks have, unfortunately, but come valved pretty decently stock, so these are absolutely the easiest upgrade with almost no hassles whatsoever. I'm riding a pair of these in extremely rocky Southeastern Kentucky / Southern West Virginia trails as often as I can make the 3.5-5 hour drive, and they feel so much better than the "better" WP 48mm forks on my wife's '07 KTM 200 XC-W. Her bike's valving and spring rates gives me a headache to ride aggressively fast (30-35mph on the faster bits, never topping 40mph) more than a half hour on this gnarly rugged rocky terrain at Redbird Crest (amazing medium difficulty trails in Daniel Boone National Forest) and Buffalo Mountain/Devil Anse and some riding at Rockhouse (all areas of the Hatfield-McCoy Trail Systems, mild logging/gas/oil road trails up to the hardest pro level singletracks you could find).

1988+ KX500 use the same steering stem length and bearing sizes as the KDX (all KDX models 1986+).
1988 are conventional 43mm cartridge forks
1989 are a 1-year-only 46mm conventional cartridge fork (sounds like a great fork to revalve for woods riding)
1990-1996 are 43mm inverted cartridge forks. I believe some of the later years there have a mid valve (93-95 KX125/250 43mm forks do).
1997-2004 are 46mm KYB inverted cartridge forks with mid valves. slightly softer valving vs the otherwise virtually identical 96-97 KX125/250 motocross forks, as there was no longer an Open Class for the 500cc 2-strokes and the bikes were tuned more for aggressive recreational riding vs well groomed MX track racing. 96-97 KX125 stock springs are .38kg rate for those riders running the KX500 forks or triples, needing a lighter spring than the stock KX500 .40kg spring. 98 125/250 forks may be the same but there was one year with a different sized top clamping area on the tubes/triples, 98 or 99 perhaps. 98-99 KX125/250 all had progressive rate springs stock, which are frowned upon. KX500 had same straight rate springs all years of the 46mm inverted forks, 97-04. KX wheel swap or KDX custom machined axle spares are needed due to different axle diameters.

KDX250 1991-1994 triples are a direct bolt in, as are their inverted forks, but the valving is a little bit odd on these, look into this further for yourself. These triples will clamp onto certain years of KX forks however.
These forks all supposedly share the same upper and lower clamping diameters:
1991 - 1994 USA KDX250
1991 - 1995 KX125
1991 - 1995 KX250
1991 - 1996 KX500
(and I am assuming KLX300R as well, see below, triples could likely be the same or nearly identical to the 1990's KDX250)

KLX300R triples apparently will clamp directly to 1993-1995 KX125/KX250 forks to bolt directly into a KDX if using the KX front wheel. As with all other KX, YZ, etc Motorcross forks, they need revalved for woods riding in order to still get traction in the rougher sections. These are also taller, but bar risers / fat bar adapters will allow you to slide these up considerably in the KLX triples. Apparently I read that you can also use KLX330 (300? 230?) springs which are similar but shorter, and some spacers in the cartridge, to lower the fork internally.

Lastly, there are a few early years of KX125/250 triples which WILL bolt directly into the KDX frames, so the forks/triples and matching KX wheel will be a direct bolt on, but as with the rest, they will need internally lowered or else bar risers / fat bar adapters added to be able to slide the fork tubes up in the triples to lower back to stock KDX height and stock intended steering geometry.
1988 KX125/250 is a conventional cardtridge 43mm fork
1989 KX125/250 is a conventional cardtridge 46mm fork
1990 KX125/250 is an inverted/upside-down 41mm cardtridge fork
1991 KX125/250 is an inverted/upside-down 43mm cardtridge fork
the 125 came stock with .37kg springs all years 88-91. The 250 stock had .38kg and .39kg (91) springs those years). The KX500 sizes/years/styles are the same 88-91 as the KX125/250 listings above.

On KX front wheels,
88-92 (& even earlier, basically all disc brake fork models) use a 17mm axle with 6203 bearings (17mm id x 40mm od x 12mm wide)
KX500 is the same but through 1993 also.
93+ KX125/250 & 1994+ KX500 use a 20mm axle with 6904 wheel bearings (20mm id x 37mm od x 9mm width). Some models as late as 2019 use this exact bearing part number https://www.partzilla.com/product/kawasaki/92045-1284
The KDX models use a 15mm axle with 6202 front wheel bearings (15mm x 35mm x 11mm)

Most other swaps of other KX forks will most likely require the KDX steering stem to be heated and pressed out of the KDX triple clamp and fit to the donor triple, as bearings are not available in the sizes needed. Other model forks will likely require the same, but I'm sure there are some that do have the required conversion bearing sizes available to make their triples a more direct fit.

Steering stops will likely have to be modified on many of these, but that is an easier detail to overcome, so I'm not looking into that part of the fitment.

Unless there is something I am missing, then the following are just a direct bolt-in swap on bearings and triple clamps:

1986 - 2006 KDX200
1997 - 2005 KDX220R
1991 - 1994 KDX250
1993 - 1996 KLX250
1997 - 2007 KLX300R
1993 - 1996 KLX650
1986? - 1991 KX125 (could be earlier)
1986? - 1991 KX250 (could be earlier)
1986? - 2004 KX500 (could be earlier)

Somebody correct me if I am wrong. Also, be sure to check steering stop engagement.

1992 + KX125 / KX250 / KX250F/ KX450F / KLX450R all have the larger top bearing.

Here's some KYB 46mm open chamber fork tips on disassembly, seal replacement, access to valving on both the base valve and the mid valve / rebound. This is the same basic fork as the 97-04 KX500, 96-98 or 99 KX125/250, and probably very similar to the 1995 mid valve 43mm KYB KX125/250 forks.

https://www.thumpertalk.com/forums/topi ... bly-guide/

[KDXGarage]

Here's a few add ons.

1995 was the first year for the midvalve.

1996 - 1998 KX125 / KX250 upper clamp is the same.
1999 - 2001 KX125 / KX250 upper clamp has the same fit and offset.
1998 - 2001 KX125 / KX250 lower clamp is the same.

The 1992 - 1995 KX125 / KX250 upper clamp offset is different than the 1991 KX125 / 1991 KX250 / 1991 - 1993 KX500 upper clamp. Obviously, the lower clamp also has the different offset. Just buy a matched set that has the offset you want.

1988 KX125 / KX250 / KX500 forks are ALMOST the same internally as 1995+ KDX forks. I am guessing the height is different, so I suggest to skip those on a KDX, as a wheel / axle swap, wheel mounting is different.

Stem outer diameter changes on various models. Buying a matching KX and KDX stem OD will keep one from needing knurling.

Watch out for forks that one can not purchase the correct rate spring for. For example, a friend switched to KLX300R forks and needed 0.42 rate springs. After $175 to a custom spring maker, he had them (as opposed to just hopping on eBay and buying Race Tech springs for much less).

One will need custom springs (Cannon Racecraft or whoever else) for 1990 KX.

1997 - 2004 KX500 forks are similar to 1996 KX125 / KX250 forks, as best I remember.

[clappy379]

Hey all - this is super helpful. I'm also wondering, outside of the add-ons above, what about the KLX250S forks? I read that the 06/07 are not the shortened versions so would those be equivalent to the KLX300 forks? I see a pair online that look fairly clean. Spring rate per the old manual online is saying 3.55 n/m.

I've decided I'd like to pursue USD forks on my KDX but I don't want to go through the hassle of the KX conversions.

https://www.ebay.com/itm/125617998107?m ... media=COPY

[KDXGarage]

Check the fork height. I am not sure of travel on those initial models.

[clappy379]

Check the fork height. I am not sure of travel on those initial models.

https://www.motorcycle.com/specs/kawasa ... etail.html

SUSPENSION:
Front Suspension Type Inverted Fork
Front Suspension Size (in/mm) 1.7 / 43
Front Travel (in/mm) 11.2 / 284.5
Front Adjustable Fork Pre-Load No
Front Adjustable Rebound Damping Yes

I think this looks more like the KDX vs the modern KLX w/ shorter travel. I know the new KLX300 is shorter, my dad has that model.