K5 SF Frame Conversion. Where do I start?

[stupidmoto]

I know this question has been asked a million times, but which KX250 frame is the best/easiest frame to convert? I've been wandering around on here for about 2 weeks now and I really can't find a conclusive answer. I read that some people say that the 99-02's are the easiest to do, but why? Where do they differ for the 03, 04, and 05-07? There is a bunch of KX250 of all different years for sale around where I live, so thats not an issue. And what all is involved? I plan on making this a Dual Sport/trail/motocross bike but most of the time it will be in street legal Supermoto trim. But that brings up even more questions like jetting, lights, etc for running on the streets. Obviously it won't be a daily driver, it will be a weekend hoon machine. Any help?

[motopunk]

the engine swap into the kx250 steelframes is always easier as in af-frames...

first you should find out, which year kx250-ergonomics you like the most ...   
1990-1993 you could always use the stock swingarm without changes
1994-2003 you have to choose between the 500 swingarm, older 250 swingarm with spacers because of the changed linkage-mounting on the frame or modify the actual 250 swingarm to the k5-engine
 in ī93 came the bigger swingarm-bolt and bigger bearings to the 250īs (on my bike i drilled the engine holes, to fit in my 93-frame ) the 500 always use the smaller bearings like the 250īs 92 and older . good way is to drill the swingarm to fit the 93 kx250-bearings-kit

1990-2002 you need to cut off the headstay and make a new front-headstay
2003-2008 have a back-headstay so i would prefer one of this bikes
 
the same things on all years are modify the front-motor-mount, modify an exhaust, and modifying the tank to fit to the bigger engine...

and here is my bike build..  http://der-motopunk.de.tl/projekt-kx500-.htm

[don46]

The 99-02 is quite easy, I would not use the 500 swingarm, the concept of going to a newer frame we make the assumption that we can get a better feeling chassis as well as handling. the 250 swingarm is easy mod if you have the tools. I've done a couple of AL framed and 1 250f steel framed. for me I like the 250f framed 500 the best, it handles well, is quite narrow and just has a good feel to it. there are boatloads of blown up 250f steelies, nice thing about these, no tank mods, no headstay mods, you do have to mod the frame cradle.

[stupidmoto]

The 99-02 is quite easy, I would not use the 500 swingarm, the concept of going to a newer frame we make the assumption that we can get a better feeling chassis as well as handling. the 250 swingarm is easy mod if you have the tools. I've done a couple of AL framed and 1 250f steel framed. for me I like the 250f framed 500 the best, it handles well, is quite narrow and just has a good feel to it. there are boatloads of blown up 250f steelies, nice thing about these, no tank mods, no headstay mods, you do have to mod the frame cradle.

Is the 99-02's any easier than the 03 and 04? What's the difference between the 99-02's and 03 and 04 modification wise? I know the headstay is in the back on the 03 and 04, but is everything else the same? What's the swingarm mod?
I do like the idea of a 250f steelie. The only problem is SF 250f's are hard to come by and expensive where I live for some reason. The cheapest one I can find is $2100! Thats pretty expensive for a donor bike IMO. I'll keep my eye out for a cheap one. But for the time being I think i'll stick with the idea of a KX250.

[motopunk]

like i said:  first you should find out, which year kx250-ergonomics you like the most ... and then do it! 
i had listed all options , which are always there for conversion... 

the idea with the earlier steely kxf 250 or rmz 250 (same bike except the plastics) i s also good option.
 in my case i had a 250 frame laying around, looked at the market which model parts are available and bought all needed parts on ebay.

the k5 engine is easier to do in the 250-frames as i thought before i had the engine...  if you take an 94- 08 frame, you could also use the 250 radiators without modifying...
 the 4stroke-rads are diferent and it needs a little bit modifying to the k5 engine , but there is nothing, that couldnīt be made... 

[don46]

Of course moto is right, find the one that fits, but, keep in mind that later models have (in most cases) better ergonomics and better suspension. Even though one might be easier to build, you still want the bike that fits you best, so take the extra time and do what is right for you. I've had 3 99-02 250 chassis 500's 1 250f Steelie and 2 aluminum framed 500's, the one I have kept is the 250f chassis. I did build another AL chassis bike thinking I didn't give the first one a reasonable chance, no it's going to go away, does not handle like the steelie, maybe it's the Ohlins shock, I don't know but it is just better feeling, more confidence inspiring

[motopunk]

 ...
 in my case, i really dont like the 99-2002 kx125/250 frames. i personally had no good feeling as i rode them. felt for me like sitting 3 meters over the ground. good bikes, but not made for me . but i love the 92-98 ergonomics and the 03-08 are similar to them.

[stupidmoto]

like i said:  first you should find out, which year kx250-ergonomics you like the most ... and then do it! 
i had listed all options , which are always there for conversion... 

the idea with the earlier steely kxf 250 or rmz 250 (same bike except the plastics) i s also good option.
 in my case i had a 250 frame laying around, looked at the market which model parts are available and bought all needed parts on ebay.

the k5 engine is easier to do in the 250-frames as i thought before i had the engine...  if you take an 94- 08 frame, you could also use the 250 radiators without modifying...
 the 4stroke-rads are diferent and it needs a little bit modifying to the k5 engine , but there is nothing, that couldnīt be made... 

Hmmmm. Well i'm not exactly sure which ones I like. The only KX bikes I have ever ridden were a 1997 KX250 (it wasn't that bad but it wasn't that good either) 1994 KX500 (ergonomics were decent but the seat was REEAAALY bad. terrible shape and position.) and a 2013 KX250F, which is the weird one, I don't if I like it or not. I'm used to riding a DRZ400SM with 17's, so any dirt bike I ride with normal dirt bike tires feel weird. But the ergonomics of the Z I like a lot. Right now i'm looking to do an 03 or 04, mainly because of the headstay, and I also like the look of them more, but i'm worried about the exhaust and swingarm bolt. Is it the same procedure as on the 99-02's?

[motopunk]

the 97 was one of the best 250īs kawasaki ever made...   

and yes, exhaust and swingarm-mods , that is needed to 03/04 conversions are similar to the older kx-frames- modīs...