KDX250af

[SS109]

Yes, you read that right! I may be on my way to doing a KDX250af conversion. I'm going to check out a clear titled '06 KX250f roller this weekend. Possibly working out a trade for one of my toys that go bang. I should know by Sunday night. I wouldn't start work on it for a while as I still have my '90 to finish up but I would start as soon as it is done.

I figure this would be a major upgrade from the '94 chassis in many ways...

204 lbs vs 236 lbs dry
226 lbs (234 with the same amount of fuel as KDX) vs 273 lbs wet
Showa suspension front (47mm) and rear with hi/low speed dampening
Better ergos
Uber cool, trick, latest rage, nothing better than, aluminum perimeter frame (I threw that last one in there for you juliend! )

I figure losing roughly 30-40 lbs should make for better acceleration, handling. braking, and overall less fatigue from a days riding. Plus, I love the cool aluminum frame and I haven't ever of anyone doing an AF conversion for the 250.

[Julien D]

lol, thanks for puttin that bit in there.

Seriously, I've been dying for someone to do this. I'm figuring this sort of swap is going to become more common too, as so many of these blown up 250f's would cost way more than they're worth to fix.

Pics as soon as possible, please :)

[chopper]

Most difficult task on this conversion will be raising the Y at the downtube/ cradle junction. This is a problem that the CR500AF builders encounter when converting a CRF 4T frame or also a CR250 2T frame because of the exhaust port location.

[SS109]

lol, thanks for puttin that bit in there.

Seriously, I've been dying for someone to do this. I'm figuring this sort of swap is going to become more common too, as so many of these blown up 250f's would cost way more than they're worth to fix.

Pics as soon as possible, please :)

Yeah, I thought you would like that! If I get it I'll post up a pic. BTW, I didn't care if I found a KX250 or a KX250F roller. This just happens to be the one guy willing to do a trade.

Most difficult task on this conversion will be raising the Y at the downtube/ cradle junction. This is a problem that the CR500AF builders encounter when converting a CRF 4T frame or also a CR250 2T frame because of the exhaust port location.

I'm aware of it. Just some cutting and TIG welding to get the engine in there. I have a great local radiator shop that can do the radiator mods I need. It really isn't as hard as everyone makes it out to be.

[frankenschwinn]

It's all just cutting and welding.

I have wondered about the need to heat treat following welding. On a bicycle frame it MUST be heat treated or the frame will fail at the area around the weld. No one ever mentions this when dealing with Moto frames. I assume it is a different grade of aluminum?

[Julien D]

I'm thinking with the jug being smaller on the 250 than the 500, perhaps you won't have a problem with the downtube? Not sure, but it would be cool to find out!

[dfeckel]

I think heat treating is still necessary with these AF conversions. At least I seem to remember reading it somewhere.

NOT and expert, though.

[ihatefalling]

Sounds cool. Looking forward to the build :)

[chopper]

I'm thinking with the jug being smaller on the 250 than the 500, perhaps you won't have a problem with the downtube? Not sure, but it would be cool to find out!

On most 4 stroke frames the Y is located very low, near the bottom of the cylinder. I'm certain that is the design of the KXF frame and relocation of the Y will be necessary.

[SS109]

I'm thinking with the jug being smaller on the 250 than the 500, perhaps you won't have a problem with the downtube? Not sure, but it would be cool to find out!

On most 4 stroke frames the Y is located very low, near the bottom of the cylinder. I'm certain that is the design of the KXF frame and relocation of the Y will be necessary.

Yes, cutting and relocating the Y portion of the frame will still be necessary. As far as heat treating goes, the guys over at KXrider.com seem to think it is not necessary. Most of them are doing KX500 conversions and riding everything from desert to MX with no problems. So, I won't be heat treating it if I do this project.

[Julien D]

Ugh. That sucks. Guess it'll still be worth it :).

[marrk_us]

Hope you get it! Take lots of pics and post often if you do. It was always a shame Kawasaki put such a nice engine with a wide ratio trans in such a heavy lump of a steel frame. (Hi Juliend) Remember reading this a while back http://twostrokemotocross.com/wp-conten ... -Build.pdf. If you get the roller maybe this will give you some ideas.

[SS109]

Well, I made the deal! Looks like it is going to be one fun conversion. I'll try to post up a pic later today.

[Julien D]

Hope you get it! Take lots of pics and post often if you do. It was always a shame Kawasaki put such a nice engine with a wide ratio trans in such a heavy lump of a steel frame. (Hi Juliend) Remember reading this a while back http://twostrokemotocross.com/wp-conten ... -Build.pdf. If you get the roller maybe this will give you some ideas.

[fuzzy]

[SS109]

Here is a crappy cell phone pic. I'll start disassembling and cleaning everything soon.

[SAPPER]

whoo first ever kxf/kdx hybrid here we go boys!

[SS109]

I'm already planning for how it will be built and for how it will look.

The engine will get a new FMF pipe and silencer (beat up PC currently). New pistons/rings and maybe a re-plate if needed. Probably have RB cut the carb slide from a #5 to a #6. That is all I have planned for the engine.

Looks wise I'm already trying to pic between the current black/green Kaw look or to do a modernized version of '90 white/blue KDX200. Yeah, I know, I have a thing for that look! So, what do you guys think, green/black or white/blue/black?

[Julien D]

I love the white and blue look.

[Slick_Nick]

Green / black!

I'm gonna be down in Marana over the holidays, (Dec 22-Jan 2) we should meet up for a beer!