1994-1998 KX250 Suspension upgrade

[Peacock]

Hi I am in the process of a 1994 KX250 Splitfire restoration.

The 94 forks are renound for being harsh.  With major advances in modern suspension I would like to swap them out for some modern forks and even the rear shock if a newer one is compatible, but it can be Rebuilt with good results.

Happy to swap out the triple tree to 1998 or any other combination.  Machining fork clamp to increase diameter ect.

Building factory bike.   So being able to achieve factory/modern suspension a class setup, is the goal to create a Retro Monster.

I am sure there is a suspension builder that could produce the ultimate package??

Look forward to hearing from you.

[sandblaster]

Prognostication or hyperbole??? 
First... I don't have much experience with the 250's like I do with the 500's so take all this with a grain of salt..
All measurements are approximate because they vary from bike to bike

1996-1998 KX250 triple clamps have a upper clamping diameter of 53.9MM LOWER 58.9MM
The KX450F triple clamps have a upper clamping diameter of 53.8MM and LOWER 59.1MM.

The top and bottom Triple bearings fit from 92-07 KX250... So if the head tube on the frame is the same length on the 94-98 then you should be able to bolt up the 96-98 triples on to your 94.

So.... you should be able to bolt up a set of 06-16 KX450F forks using 96-98 KX250 triple clamps.

The 94 kx250 front brake caliper uses a center to center of mounting bolt length of 102mm and so does the KX450F so you may be able to use your front brake providing the front brake rotor offset is the same. I have no info on that.. But you can use your 94 front brake master cylinder with the 450f caliper.

You will need the 450f axle and likely the spacers.

Number plate? not a clue 

More on the shock in a bit...

[sandblaster]

On the shock.... The 250f and 450f shocks are too long...
However, if you unscrew the Clevis off the bottom of the 94 KX250 shock and screw it on to the bottom of the 250f or 450f shock it will bolt right in.
The next issue will be the shock reservoir.
On the 500's the 250f 405f shock reservoirs hit the pipe.
Never tried it on the KX250's so hopefully somebody else has.
Post your results with pics 

[kmc14]

The resevoir will not fit on the 98. 03 and up will fit if you change the clevis. On the 02 and back the subframe bolt is in line with the top shock bolt and resevoir will hit subframe.

[sandblaster]

Cool!
But here is a reality check...
If you compare the rear shock piston, stroke, and bladder, from a 2012 KX450F and your 1994 KX250 you won't see much difference.
Sure, it is nice and I would probably do just because.
But, if you get either shock properly valved and sprung either will likely handle all you can dish out.

[KXDINO]

Blaster right , what i would do is put a gold valve in the shock , if there one thing they do good is you notice that the rebound clickers really change when you adjust the clickers where the stock stuff hardly do a thing .

[sandblaster]

I've used the Gold Valves for years with good success.
Recently we put Pro Action valving in Sean Collier's bike and he loves it.
After closely inspecting their valve set up it is almost identical to the gold valves.
So if you want to save a few bucks, PM Alward25 and see what he can do it for you at.

[Peacock]

Thanks, sandblaster, KXdino,kmc14,

Really appreciate the info.  It actually adds some reassurance to the direction I was goin to take.

Billited 1998 triple tree/clamps.  New 14-16 forks caliper spacers ect.  Full rebuild of shock gold valves "thanks guys"

Im looking at new wheels and hubs so I'll have to check the wheel 1994 kx wheel size against the newer 450kxf Wheel sizes.

The original bike was in very very poor condition, battered bruised and rusty.  Pulling it down today and some bearings just fell apart rusted out.  The plastics just desinergrated and the list gos on. 

I'll post pictures of the build.  It is my first restoration, so will need some advice on the build.

If anyone has done this upgrade to the front end of a 1994-1998kx share your results.  Any further info would be appreciated.

[kmc14]

I put 07 kx450f forks on my 98 KX 250(with 500 engine) years ago. I used an 03 swingarm and run the 450 wheels and brakes. The 450f forks fit right in the 98 triple trees.

[Peacock]

KMC14 What swingarm did did you use assuming you used a 03 kx 250 swingarm or was it a 03 kx450f swingarm?

[kmc14]

I used the 03 kx250 two stroke swingarm. You can use the 98 linkage knuckle but the bearings are bigger than the 03. Better to get 03 knuckle so 03 bearings for entire rear suspension. My email is kx250af@gmail.com if you want to know more.i don't check site everyday.

[RonWilder]

Prognostication or hyperbole??? 
First... I don't have much experience with the 250's like I do with the 500's so take all this with a grain of salt..
All measurements are approximate because they vary from bike to bike

1996-1998 KX250 triple clamps have a upper clamping diameter of 53.9MM LOWER 58.9MM
The KX450F triple clamps have a upper clamping diameter of 53.8MM and LOWER 59.1MM.

The top and bottom Triple bearings fit from 92-07 KX250... So if the head tube on the frame is the same length on the 94-98 then you should be able to bolt up the 96-98 triples on to your 94.



             Do you know if the 1998 triple clamps will fit on a 1994 kx250 frame?