KDX250 hybrid - what chassis?

Discussion for swapping a KDX motor in a MX frame...
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SS109
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KDX250 hybrid - what chassis?

Post by SS109 »

Just thinking ahead here. It seems the one downfall of the KDX250 was the chassis setup. I'm thinking of possibly building a hybrid using the KDX250 engine in the future.

So, what chassis would work for this? The KX125 like 200/220 hybrids or would I need to step up to a KX250 chassis? What about the KX250F/450F chassis? Yeah, I know the 4t bikes would need the frame cut and TIG welded for the 2t pipe but other than that, what other pro/cons to them?
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Post by KarlP »

I think any 2000+ chassis can be made to work.

I personally think I would go with a steel frame if I was going to do another.
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Post by Tedh98 »

How much larger is the 250 motor over the 220/200?
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Post by Julien D »

Considerably larger. The kdx200 engine was designed after an early model kx125 engine, the KDX250 engine is basically a de-tuned kx250 power plant.

I think you'd be hard pressed to fit it into a KX125. If it were me, I would look for a kx250 roller. Should be a relatively easy swap.
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Post by Tedh98 »

I would agree then on going with a 250 roller.

With the engine in place, there really isn't that much room between it and the downtubes near the exhaust.
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Post by SS109 »

KX250 it is. Thanks for the input.
Youtube Channel: WildAzzRacing
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Current KDX: '98 KDX220
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Post by ldspowersports »

How is the build coming along?

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Post by SS109 »

My 200 or the 250? The 200 is stalled right now due to my car taking a dump and the 250 won't get started until I find a reasonable priced roller sometime down the road. I can't hardly find KX250's around here. Lots of Yamaha YZ's though. Maybe a YZ-KDX250 hybrid?
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Post by Julien D »

I think the YZ would be doable.
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Post by SS109 »

Yeah, but where can I find green plastics for it! :mrgreen:
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Current KDX: '98 KDX220
Old KDX: '90 KDX200 -White/Blue
'11 GasGas EC250R
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Post by Julien D »

No green, but black and white would look good!
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Post by SS109 »

Found a good deal on a '06 KX25F chassis with a blown top end. (I can feel juliend cringing right about now!) Hey, the weight that year for the KX250 and F were the same. That would lead me to believe that the F frame is actually lighter than the KX steel since the 4t engine should be heavier than the 2t.

Anyways, trying to decide if I want to go with it or not. It would make an awesome hybrid for the KDX250 engine if it would fit. Anybody have a clue if it would? Also, I know the frame would have to be cut and welded, the radiator outlet on the left side would have to be modified, the usual engine mounts, and swingarm/rear case mods but is there anything else?
Youtube Channel: WildAzzRacing
AZ State Parks & Trails OHV Ambassador - Trail Riders of Southern AZ
Current KDX: '98 KDX220
Old KDX: '90 KDX200 -White/Blue
'11 GasGas EC250R
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