2002 KDX200 -> 1998 KX125
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2002 KDX200 -> 1998 KX125
Hi Guys and Gals!
Finally found time to share my hybrid build. It's almost finished, but I don't see many people using the 94-98 KXs, so I wanted to show how I went about it..
First, acquire derelict chassis - $60
Next, strip super nice KDX (acquired from my friend in 2012, who was the OO since 2002)
From this:
To this:
Next, sell bottom end? (Still available in the Parts & Bikes forum!!)
https://scontent-a.xx.fbcdn.net/hphotos ... 8110_n.jpg
Mocked up frame and rear end.
I decided to use the entire KDX rear suspension- rocker, dogbones, shock, swingarm, everything.
First, drilling out a case is really freaking hard without good drill bits, which are expensive.
Second, should I ever want to sell the KDX engine, it will technically be unmolested. Although, I really am itching to send it off to RB to get the full monty!
Now the slightly unfortunate- while paint stripping and breaking down the KX, I noticed a sheared engine cradle tube. It was still barely attached, but I wanted to cut out the cancer and fix it for good measure:
Being a suspension engineer by day, I wanted to at least make sure the ratios in the rear were going to be *close*. Maybe not perfect, but for peace of mind, I mocked up the rear suspension of each bike in Creo, and made manipulable suspension models with sketches and proper constraints.
Here's the graphed result of the progressiveness of each setup.
Alright, so now I know I'm going to use the KDX rear. Next step was to fab some bushings to downsize the 17mm KX swingarm pivot holes to 14mm. Word of warning, making a sturdy bushing of wall thickness (17-14)/2 = 1.5mm, or ~.060in is REALLY hard. I have years of machining experience, and it was damn-near impossible on the equipment I had (backwoods engine lathe, nichts on the accuracy...)
I patiently dremelled and sanded out the holes to about 18mm. Believe it or not, the extra .020 of wall thickness this gave me was a savior. I'm sure with a good lathe, you could make a 17mm bushing w/ a 14mm hole, but it wasn't an option for me. So here's the finished product. It's very very close to round, despite the perspective of the pic (maybe 1-2 thou out.)
With the swingarm and engine ready to bolt on, I mocked up the engine position, basically bringing it low enough for the bottom of the engine to be about parallel with the lower cradle tubes. Here are the resulting mounts:
And just like that, it's ready for powdercoat!
And for the past few days I've been reassembling. I was annoyed with 12 years of dirt stains on the engine, so I read up and used Eagle One Mag Wheel Cleaner- used for rough aluminum castings. It worked like a charm...
Before:
and After:
Engine in, swingarm in, front forks rebuilt and assembled:
Just received a new OEM Acerbis plastics kit today, assembly to continue this week!
Finally found time to share my hybrid build. It's almost finished, but I don't see many people using the 94-98 KXs, so I wanted to show how I went about it..
First, acquire derelict chassis - $60
Next, strip super nice KDX (acquired from my friend in 2012, who was the OO since 2002)
From this:
To this:
Next, sell bottom end? (Still available in the Parts & Bikes forum!!)
https://scontent-a.xx.fbcdn.net/hphotos ... 8110_n.jpg
Mocked up frame and rear end.
I decided to use the entire KDX rear suspension- rocker, dogbones, shock, swingarm, everything.
First, drilling out a case is really freaking hard without good drill bits, which are expensive.
Second, should I ever want to sell the KDX engine, it will technically be unmolested. Although, I really am itching to send it off to RB to get the full monty!
Now the slightly unfortunate- while paint stripping and breaking down the KX, I noticed a sheared engine cradle tube. It was still barely attached, but I wanted to cut out the cancer and fix it for good measure:
Being a suspension engineer by day, I wanted to at least make sure the ratios in the rear were going to be *close*. Maybe not perfect, but for peace of mind, I mocked up the rear suspension of each bike in Creo, and made manipulable suspension models with sketches and proper constraints.
Here's the graphed result of the progressiveness of each setup.
Alright, so now I know I'm going to use the KDX rear. Next step was to fab some bushings to downsize the 17mm KX swingarm pivot holes to 14mm. Word of warning, making a sturdy bushing of wall thickness (17-14)/2 = 1.5mm, or ~.060in is REALLY hard. I have years of machining experience, and it was damn-near impossible on the equipment I had (backwoods engine lathe, nichts on the accuracy...)
I patiently dremelled and sanded out the holes to about 18mm. Believe it or not, the extra .020 of wall thickness this gave me was a savior. I'm sure with a good lathe, you could make a 17mm bushing w/ a 14mm hole, but it wasn't an option for me. So here's the finished product. It's very very close to round, despite the perspective of the pic (maybe 1-2 thou out.)
With the swingarm and engine ready to bolt on, I mocked up the engine position, basically bringing it low enough for the bottom of the engine to be about parallel with the lower cradle tubes. Here are the resulting mounts:
And just like that, it's ready for powdercoat!
And for the past few days I've been reassembling. I was annoyed with 12 years of dirt stains on the engine, so I read up and used Eagle One Mag Wheel Cleaner- used for rough aluminum castings. It worked like a charm...
Before:
and After:
Engine in, swingarm in, front forks rebuilt and assembled:
Just received a new OEM Acerbis plastics kit today, assembly to continue this week!
- 6 Riders
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Re: 2002 KDX200 -> 1998 KX125
Nicely done...wanna build one for me?
newbbewb wrote:^what he said.
*side note...I'm drunk, so try to read what I'm trying to say, instead of what I actually typemasterblaster wrote:Man 6 riders you rock.
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Re: 2002 KDX200 -> 1998 KX125
Damnit, KDX shock is a couple mm too wide for the KX mount.....sheeeeeeet
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Re: 2002 KDX200 -> 1998 KX125
I've got a rear shock and spring off a 97 KX 250 I can sell you, if you are interested. Not sure how it compares to the stock one on the KX 125.DoubleA wrote:Damnit, KDX shock is a couple mm too wide for the KX mount.....sheeeeeeet
- Tedh98
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Re: 2002 KDX200 -> 1998 KX125
Looks good.
Sorry to hear about the shock, but I'm sure you will figure out a solution.
There is a lot of room in that frame, looks more like a 250 frame than a 125.
Sorry to hear about the shock, but I'm sure you will figure out a solution.
There is a lot of room in that frame, looks more like a 250 frame than a 125.
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Re: 2002 KDX200 -> 1998 KX125
TN Dirtrider wrote: I've got a rear shock and spring off a 97 KX 250 I can sell you, if you are interested. Not sure how it compares to the stock one on the KX 125.
]
Thanks, but I have the original KX one still.
I thought about shaving a bit off the sides of the KDX top mount, but I'm just going to use the KX shock and rebuild it with the Moose Racing seal kit.Tedh98 wrote:Looks good.
Sorry to hear about the shock, but I'm sure you will figure out a solution.
There is a lot of room in that frame, looks more like a 250 frame than a 125.
You had me worried a bit on the frame! Ran the VIN through the Kawasaki checker, and it is indeed a 125.
Anyone need a KDX shock? Great condition, pics in my F/S thread!
- Tedh98
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Re: 2002 KDX200 -> 1998 KX125
What pipe are you going to use? It looks like you will wind up extending that quite a bit.
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Re: 2002 KDX200 -> 1998 KX125
Yeah, still have to think about that hurdle. I currently have a PC Platinum II pipe and PC Factory stainles silencer.
Mock up seems to clear with about 1-1.5" of extension to the head pipe. Any ideas on good extension solutions?
Mock up seems to clear with about 1-1.5" of extension to the head pipe. Any ideas on good extension solutions?
- Tedh98
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Re: 2002 KDX200 -> 1998 KX125
Sorry, I can't help with that, I didn't have to touch the pipe on mine.
I do remember seeing one or two builds where an extension was added. Maybe one involved a CR. A search may find those.
I do remember seeing one or two builds where an extension was added. Maybe one involved a CR. A search may find those.
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Re: 2002 KDX200 -> 1998 KX125
Alright, note to self/all. Fit the pipe before you weld engine mounts. It saves headaches....UGHHH
Going to cut off the Header pipe inlet and press in or weld a small length of tube to push the pipe out about 3/4".
Subsequently, this also caused carb fitment problems. The carb is about 1/2" too far back to go into the boot correctly. I'll post pics of my plan when I get around to tackling that best. Might have to do a cut-and-shut job to modify the boot, but by god I'll make it work!
Going to cut off the Header pipe inlet and press in or weld a small length of tube to push the pipe out about 3/4".
Subsequently, this also caused carb fitment problems. The carb is about 1/2" too far back to go into the boot correctly. I'll post pics of my plan when I get around to tackling that best. Might have to do a cut-and-shut job to modify the boot, but by god I'll make it work!
- Tedh98
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Re: 2002 KDX200 -> 1998 KX125
Do you have a picture of the other side of the bike showing what the swing arm and sprocket positioning looks like?
That positioning should be done first with the boot and pipe adjustments second.
That positioning should be done first with the boot and pipe adjustments second.
- bufftester
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Re: 2002 KDX200 -> 1998 KX125
You probably would have gotten a lot more bang for your buck by swapping the KDX and KX forks. For the amount of work you have put into it you have transplanted the KDX motor from a frame that was derived from the mid-90s KX, into an actual mid-90s KX. That frame has a lot of room around the motor, are you sure it's not a 250 frame? The header extension will cost you several hundred rpms up top which may or may not be a concern depending on the riding you do.
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Re: 2002 KDX200 -> 1998 KX125
Positive it's not a 250 frame....unless the Vin on the steering neck is wrong....
Yeah I understand the extension is going to shave some off the top end, but I'm mostly riding tight woods in the Carolinas. There isn't too much WOT down here, at least where I ride.
In hindsight, yeah it wasn't the easiest thing in the world to do, but hey, at this point I want to finish it and finish it right!
Plus, it was a hell of a learning experience.
I've been into a lot more MX lately, and I've always used supermoto as training for my road racing, so when I'm finished I'm going to probably ride it, see how I like it, and go from there.
Yeah I understand the extension is going to shave some off the top end, but I'm mostly riding tight woods in the Carolinas. There isn't too much WOT down here, at least where I ride.
In hindsight, yeah it wasn't the easiest thing in the world to do, but hey, at this point I want to finish it and finish it right!
Plus, it was a hell of a learning experience.
I've been into a lot more MX lately, and I've always used supermoto as training for my road racing, so when I'm finished I'm going to probably ride it, see how I like it, and go from there.
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Re: 2002 KDX200 -> 1998 KX125
Have you finished this?