Maintenance & Technical > KX500 Steel Frame Conversion (SFC)

KX250 Chassis With 500 Motor

(1/17) > >>

BigGreenMachine:
Hey guys, what would it take to put a KX500 motor in a KX250 chassis? Does it fit at all? Can you use the airbox and not have to mod the tank?

don46:
I Can't speak for all years of 250, but, the 99-02 is quite easy to do. My avatra is a 05 250f chassis, its a pain in the a$$. The 250 conversion will require the swingarm to be narrowed about 8mm on each side, the swingarm motor mount to be drilled to 17mm, the head stay cut off the back of the motor and a new one fabricated on the front of the head, the 250 fron motor mount will be removed and repositioned, the bottom mount will fit, The pipe has to be modified, some guys are using a CR500 pipe and denting it around the water manifold and kick starter. The air box works as is, either use a short ceramic plug or warm the gas tank a bit and push up the bottom to gain clearance for the plug. This makes an awesome bike that handles night and day better than the stocker, the 250 has better suspension than the k5 and is much narrower.

MadKaw:
got me hurtin on that one...got the stuff, but scared of the mods.

KXcam22:
Don,
  I take it that you mean the 99-02  2-stroke 250 is the easiest frame to convert to 500 power.  Can you give me a rough list of things that you had to mod. Thanks. Cam.

don46:
You are correct, 99-02 250 2t. Front motor mount needs to be re-positioned, swing arm spacers and the actual swingarm need to be narrowed to accomodate the k5 motor. bottom motor mount should be OK, motor needs to have the swingarm bolt mount drilled to 17mm, pipe needs to be modified to fit the 250 chassis, head stay cut off and new one fabricated.  Pretty much what I'd said in my first post. I bought all the parts off ebay for 600-700 bucks and then rebuilt everything.  I can take some pictures and show you the mod to the swingarm. It is truly an easy swap if you have a modest amount of mechanical ability, at most 1 weekend. I would say the pipe is the most time consuming part.

Navigation

[0] Message Index

[#] Next page