KX500 motor swap into a '06KLX250s


10 replies to this topic
  • smokemetallic

Posted August 20, 2008 - 02:40 PM

#1

Has anyone tried this? Is it feasible at all. Seems like it would be easier then an aluminum frame conversion because the KLX has a steel frame which I could have welded a lot easier if needed. Using the klx is the easiest way for me to get a big horsepower kawi supermoto legal on the street in my state.
I did a search and came up blank.. much appreciated for any input. Thanks.

  • ebeck

Posted August 20, 2008 - 06:07 PM

#2

bunch have done KX/KDX swaps. Just make new motor mounts. One thing to look for is will the exhaust clear the frame downtube.

Guy out here has an alumiu frame KX2560 with a KX500 moto that is supermoto'd out. Apparently he kills the sport bikes.
Good luck!

  • smokemetallic

Posted August 20, 2008 - 06:35 PM

#3

How similar is the kdx frame to the klx 250? I know theyre both perimeter but how different size wise?

  • MetalMan1011

Posted August 20, 2008 - 09:11 PM

#4

bunch have done KX/KDX swaps. Just make new motor mounts. One thing to look for is will the exhaust clear the frame downtube.

Guy out here has an alumiu frame KX2560 with a KX500 moto that is supermoto'd out. Apparently he kills the sport bikes.
Good luck!


Your right about killing the sportbikes, my friend has an R6 and he can't even come close to me at anything less than freeway speeds:ride:
-------------------------------------------------------------------------

I'm sure you could make it work, but I would expect a lot cutting, welding, and fabrication. I have actually never seen it done with a KLX. Although, I used to have a '96 KLX250R (which is virtually the exact same bike you have), and I think it would be easier to do the engine swap with that rather than with a KX250F like I did. From what I can remember there should be more room in the KLX frame, I know for a fact the KLX engine is less compact than the 250F motor. Prepare for massive amount of vibration. Check all your engine mounts and check them often, along with everything else that could vibrate loose...

Things you will most likely will have to do:

Change all the engine mounts
Modify the airbox (the KX and KLX carbs are different sizes, so the air boot won't match)
Modify a CR500 pipe and silencer
Machine the engine cases where the swingarm bolt goes, and possibly change the diameter of the hole because the bolts might not be the same size
Make your own radiator hoses

Other than that there will be a bunch of little modifications that will be needed.

On my bike I needed to modify my gas tank because the bigger engine wouldn't fit, but I don't think you would have a problem with that because the KLX cylinder sticks up a lot farther than the 250F.

And the big modification, I had to cut a piece out of the downtube and weld in an "O" shaped piece for the pipe. You can see it pretty good in this picture:
Posted Image

  • KDXGarage

Posted August 21, 2008 - 10:48 AM

#5

Can you plate a KDX in NY?

  • Jeekinz

Posted August 21, 2008 - 12:07 PM

#6

Isn't it a KLR that's street legal? I rode a friend's KLR250 off road once. The suspension would bottom out on a curb.

I was toying with the idea of using a KLR250 frame with a 450 motor SM'd out for the street. But it would take a crap load of work. You would have to change the suspension, swingarm, motor mounts...you name it. And you would have to keep the headstock for the VIN.

I would stick with a four stroke so you aren't limited to the range of your premix.

I hope Kai builds something like the SXV. If not, I'll be buying a KTM or one of those other exotics.

  • zz3gmc

Posted August 21, 2008 - 12:26 PM

#7

The KLR was replaced by the KLX a few years ago. To the original poster, I would look for a NY titled KX250 that was used for enduros. It would be a much easier conversion. They are out there, you just have to keep an eye out.

  • MetalMan1011

Posted August 21, 2008 - 12:54 PM

#8

The KLX250 came out in the early nineties, I believe in 93, more than a few years ago. I swear nobody knew about these bikes until the "S" version came out. I need to get me another one, I could go anywhere on that thing.

The KLX250R were only sold in the US for 3 years, '94, '95 and '96, until it was replaced with the KLX300. One of the best bikes I have ever owned. It was light for its time( I believe 230), water cooled, inverted forks, made good power, ect... Seriously, I think it was basically the first "modern four stroke", way before that so called, "magical" YZ400F. It was light years ahead of the XR250, and it was just as reliable.

Plus, it had the best exhaust tone of any dirt bike I have heard, with a PC T-4:busted:

KLX250S:
Posted Image

1995 KLX250R:
Posted Image

KLR250(LAME:lol:)
Posted Image

  • zz3gmc

Posted August 21, 2008 - 01:39 PM

#9

I knew about them, he was asking about the street legal one which came out a few years ago. Was street legal in Japan since its inception. My brother has a Stroker Racing (Larry Roeslers old company) KLX331 with a lengthened swing arm, KX500 suspension up front and a modified KLX shock with KX internals.

  • smokemetallic

Posted August 21, 2008 - 02:15 PM

#10

Can you plate a KDX in NY?

Yes but its not really worth the trouble, and its not exactly legit unless it was street titled in another state.

I would stick with a four stroke so you aren't limited to the range of your premix.

.


I've got a killer '06 Husqy 510 sumo. looking to have the kawi as a back up bike. Would like to have equivalent HP as my Husqy and be street legal. the only kawi setup that works is the kx500 motor in a road legal chassis or a 450F motor, but i dont think that would hold up.
Distance between fuel stops is not an issue as I can only go 70-80 miles on my 510 at a time and the 2 stroke would be similar.

anyways im going to attempt this project. need to start putting the parts together. Thanks for all help.

  • MetalMan1011

Posted August 21, 2008 - 02:18 PM

#11

I knew about them, he was asking about the street legal one which came out a few years ago. Was street legal in Japan since its inception. My brother has a Stroker Racing (Larry Roeslers old company) KLX331 with a lengthened swing arm, KX500 suspension up front and a modified KLX shock with KX internals.


I wasn't specifically talking to you but it just seems they are pretty unknown.

I read about guys who would race them in the 125 class back when there were no other 250F's except the YZ250F. They would put KX bodywork on, KX suspension, carb, a bit of motor work, ect... and they would end up grabbing the hole shot against the YZF's and 125's. Not to bad for a 90's enduro:applause:

Damn, now I want to get another one:goofy:





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