Getting started project KX5 in 06 Aluminum frame

[hangtime]

Howdy everybody,
Thanks for all of the great info you have accumulated, it has helped me alot. I am just getting started on this monster and will post pics as I go. I'm building this around the 87 KX5 motors. I like the simplicity of their power valve design versus the guillotine style. And within four weeks I was able to buy two complete motors, local and through ebay. I am using one set of case halves and a cylinder as dummies to set the motor in the cradle, and the built motor will be ready in a couple of weeks. Having gone into the local Kawi dealership with my calipers and camera enough to make them nervous  :wink I have chosen the KX450F over the 250F frame to be the best "donor" vehicle. With the 07 KX450F coming with a 5 speed tranny I think they 06 will quickly become outdated and available somewhat cheap. I personally like to wrench as much as ride and this will probably be my last bike so I'm going for greatness. Is it too early to ask how I should jet this thing or if reed spacers really work

Thanks

[hughes]

Bubba blew an 06 model up last week at southwick race might get that bike cheap   

[hangtime]

If that was a KX500 it would have never blown up!!!

[Danger4u2]

If that was a KX500 it would have never blown up!!!

  Hate to say.......
http://www.kxriders.com/forums/index.php/topic,2365.0.html

[gowen]

LOL! @ 10,000 RPMS though!

If that was a KX500 it would have never blown up!!!

  Hate to say.......
http://www.kxriders.com/forums/index.php/topic,2365.0.html

[KXcam22]

Yeah Doordie likes to spin them fast. Lots of overrevving going on on the ice!!

 Hangtime,
   You also might be able to find a grenaded one with some phone calls to dealers.  Someone who has to put $3K or more into a motor repair might be real interrested in selling it sans motor. Worth some calls anyway. Good project. Keep us posted. Cam.

[emullen]

Hangtime-

Great bike.  I'm considering the transplant myself.  If you don't mind, can I ask a few questions so that I do not have to reinvent the wheel- know what I'm saying?  First (of many, I'm sure, and thanks in advance for your help), why did you choose the 450 over the 250 frame?  Will the 250 work? I have a chance to get a 250 so I would like to use it for that reason if it is workable.

Thanks,  Eric

[hangtime]

Howdy emullen,
I chose the 450f frame because it appeared to me that the engine cradle and the down tube on the 250f frame were prohibitive. The engine cradle tubes begin an upward bend too early to meet the down tube. The down tube appears to be at an angle that would pass through about where the front of the 500 cylinder needs to be. That does not mean you couldn't cut out and weld on more of the down tube (starting  closer to the steering head tube) and  cradle, but the new piece (down tube) would be welded on at a different angle than the original. This in my mind puts up a lot of red flags, the load that passes down that tube needs to continue along the same (original) plane. Also there is a second wishbone that attatches the down tube to the upper frame spars. I would not recommend cutting above that point. That actually carries more load than the engine cradle/wishbone below it. Lastly, the cast piece on the 250f where the swingarm bolt passes through has a different bend to it. I think this might interfere with a 500 kickstarter.

Keep in mind I have never actually tried to set the 500 motor in the 250f, all of my conclusions were based on photos and simple overlaying a 500 motor on the two frames in photoshop. Hit me with as many questions as you want, I'll be glad to help.
 

[kx666]

there is a guy in californa doing this with CR500s. he actually has acontract with honda. honda sends him the parts (compleate motor) last i heard of him was in eary 2005, he had the new 2005 CR 250 (before some of the dealers had the bike) would pull the motor using in for a kart, them stuff a cr500 in it and would sell them for about $10,000

[ebers17]

Yeah, Service Honda does that.  www.servicehonda.com and you'll see all the information about it.

[emullen]

Hangtime,

thanks for your reply.  We tried the k5 motor in a RMZ 250F frame today and you are correct about the downtube and exhaust pipe.  We pretty much stopped at that point and decided that we would think it over - if we should attempt any modifications.  I was told that there is someone running a k5 in a rmz 250 frame in FTR ( Florida trail riders) but we will have to further investigate that.  Does your 450 have a single downtube or does it have 2 like the k5 frame.  If you have a picture of the pipe and downframe that you could shoot over we would appreciate it.

Thanks

[hangtime]

emullen,
I assumed you were talking about an aluminum 250f frame. I am not sure however about the 250f steel frame. If you check out my gallery you can see most of the mods needed. The photo 12/15 in my gallery you can see just how much was removed, then in photo 11/15 you can see the pieces added to complete the new wishbone.

[emullen]

Hangtime-

We had a steel frame available to us.  I would prefer the Aluminum.  I am going to have to find a 450 aluminum frame I think to make it work.  it has the split downtube.  That was the the real factor.  Otherwise it will require heavy modification.

[hangtime]

Remember, on the 450f frame you will have to cut out the "split downtube" or "wishbone" and move it up to make room for the 500 head pipe.