2006 CRF250 + 2004 KDX 200

Discussion for swapping a KDX motor in a MX frame...
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Goatsby
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2006 CRF250 + 2004 KDX 200

Post by Goatsby »

New to the board and KDXs, I recently bought an 04 200 for $140 dollars, was a theft recovery and the guy couldn't get the bike to run again, was spray painted all sorts of colors, had given up on it and had it sitting in the garage, been crashed pretty hard, wouldn't start. The rear subframe area is snapped off, there is a crack elsewhere in the frame, the forks are blown, the front brake does not work. I took the bike home to give it a look over, found the plug wire loose, put some premix in it, kicked it about 70 times and she started! Took her for a quick ride around and I'm in love with the engine. I'm currently building an 03 KTM 200 that will hopefully compare!

I didn't have plans for what to do with the bike after buying it, then I started reading about hybrids, and it seemed cool, so I thought if I could do this on the cheap and not spend too much money on it..Why not start another project.

I found an 06 CRF250 the next day. The bike was 300 without the front end, and the engine is locked up. Before I get into it too much going to list everything up on ebay, then figure out where I need to start chopping things and welding. Will post some pics of what I'm starting off with tomorrow!
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Re: 2006 CRF250 + 2004 KDX 200

Post by bufftester »

The biggest challenge is just cutting the front downtube/lower engine cradle to make room for the pipe. Been done plenty of times so not impossible. Then it's just fitting the bits. Will make a very fun ride!
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2006 CRF250 + 2004 KDX 200

Post by Goatsby »

If no parts for my KTM come in tomorrow I'll get to work stripping down the KDX and see where I need to chop the Y. Hopefully my aluminum welding skills are up to par!
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Re: 2006 CRF250 + 2004 KDX 200

Post by KDXGarage »

Good luck on the build.

I hope your welding skills are up to par, too. :shock: :shock: :grin:
Thank you for participating on kdxrider.net. :bravo:
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Timtee
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2006 CRF250 + 2004 KDX 200

Post by Timtee »

Goatsby wrote:Hopefully my aluminum welding skills are up to par!
That is an understatement!
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Re: 2006 CRF250 + 2004 KDX 200

Post by Goatsby »

I'll practice on some plate before I get to the frame I think, last time I did it the welds were..functional. Not pretty but functional :grin:
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Molly's 70
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2006 CRF250 + 2004 KDX 200

Post by Molly's 70 »

Timtee wrote:
Goatsby wrote:Hopefully my aluminum welding skills are up to par!
That is an understatement!
The good news is that your entire KDX frame is made from steel. To be certain, you can use the magnet test. Aluminum is non magnetic, steel is magnetic. I weld 40+ hours a week in aircraft.(TIG) Been doing it on & off for almost 30 years. I hate my job, but I love welding. Anyway, if you have any questions, I can probally help. Would love to help.

Here are the first three rules for welding. (especially aluminum)
1- Clean
2- Clean
3- & Clean
No rust,paint,grease,powdercoat,oil,or any other crap that will contaminate the heat affected zone. (ie. weld pool)
Protection/shielding of the weld pool is the most important thing about welding.
If you lend someone $20, and never see that person again, it was probably worth it.
Goatsby
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2006 CRF250 + 2004 KDX 200

Post by Goatsby »

definitely, going to pick up some more gas here and practice on some AL plate I have first, I've gotten a little better. Before I was really easily blowing through the material.
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Molly's 70
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2006 CRF250 + 2004 KDX 200

Post by Molly's 70 »

How thick is your aluminum plate? I assume your using argon for shielding?
If you lend someone $20, and never see that person again, it was probably worth it.
Goatsby
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2006 CRF250 + 2004 KDX 200

Post by Goatsby »

Yep just straight argon, 1/16". I haven't looked into how thick the walls of the cradle/Y piece are yet.
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2006 CRF250 + 2004 KDX 200

Post by Molly's 70 »

Perfect, 100% Argon, 4043 filler rod, A/C current. Get that aluminum really clean. It is also recommended to use acetone with a new stainless steel brush. Don't rush your puddle. Let the machine use it's a/c cleaning action. I like to put a small ball on my tungsten. It's that oxide layer that messes with everyone.
If you lend someone $20, and never see that person again, it was probably worth it.
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2006 CRF250 + 2004 KDX 200

Post by KDXGarage »

Molly's 70 wrote:Perfect, 100% Argon, 4043 filler rod, A/C current. Get that aluminum really clean. It is also recommended to use acetone with a new stainless steel brush. Don't rush your puddle. Let the machine use it's a/c cleaning action. I like to put a small ball on my tungsten. It's that oxide layer that messes with everyone.
:shock:
:bravo:

This guy's a real welder. The closest I ever got was a J-B Welder. :lol:
Thank you for participating on kdxrider.net. :bravo:
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Timtee
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2006 CRF250 + 2004 KDX 200

Post by Timtee »

Goatsby wrote:definitely, going to pick up some more gas here and practice on some AL plate I have first, I've gotten a little better. Before I was really easily blowing through the material.
This may come off harsh, but the welds on the cradle are critical and need to be done properly. If you are still in the practicing phase you should really let somone who knows what they are doing handle the welding. Your safety is at stake here.

There are lots of pictures out there of failed welds on AF conversions.
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2006 CRF250 + 2004 KDX 200

Post by Molly's 70 »

Your 1/16" thick or, (.063) as we call it, is what they use to certify us where I work. Usually 6061 for aircraft. I prefer the 4043 filler rod. The extra silicon content promotes a more fluid puddle. I have used many different aluminum filler material though the years, but that 4043 always seems to work out the best.

As another poster stated, bad welding jobs can be disastrous. We always need to keep safety in mind.

You have to remove that oxide layer on aluminum to get it done right. Clean, Clean & Clean for aluminum.
You can do it if you want to. Those 1/16 plates are great practice. Post pictures of your practice if you can. Don't be scared to show me.

If your welding/learning experience, does not piss you off a few times, you'll never get better. :grin:
If you lend someone $20, and never see that person again, it was probably worth it.
Goatsby
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Re: 2006 CRF250 + 2004 KDX 200

Post by Goatsby »

Will do, thanks Molly! I'm in no rush to get it all welded up into the frame yet, so a while practice will do me some good. I'll post some pics up here of what I'm starting off with, this project I'll be working on in between my KTM 200 build as well. Matching 200s :)
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2006 CRF250 + 2004 KDX 200

Post by Goatsby »

So now that my KTM is just about done..Onto this project.

I bought both of these bikes a while ago. The KDX is an absolute turd. It is mangled and beaten within an inch of its life. It is a theft recovery, I paid 130 dollars for it. Believe it or not it actually ran in this condition, and I rode it up and down the street and it shifted through all the gears. I already took off the carb to throw it in the ultrasonic cleaner and the pipe so I can restore it, it's an FMF gnarly. The piston is shot and very scratched looking into the exhaust port, but for 130 bucks you can't go wrong.

Image
Image
Image


Next up is the transplant receiver. I bought this bike for 300 dollars, and recieved the whole bike in a box sans the front end. These bikes are very very popular to blow up so I'm hoping to get a complete front end on craigslist for cheap. The carb has already been sold for 175 dollars and most of the cost is recouped.

Image

So now the plans. I'd like to be a bit more meticulous about documenting and working on this bike than my KTM. I started rushing through it at the end because I really wanted to get out riding again as it's been a while. That should be this upcoming weekend! I'm going to part out the engine from the CRF on ebay and see if anything salvageable is left on the KDX to sell.Neither of the brakes work and the front rim seems bent. So maybe the only thing good there is the rear wheel, and the possibly the forks, will have to check for straightness.
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Re: 2006 CRF250 + 2004 KDX 200

Post by KDXGarage »

Ah. There you are. Thanks for posting the follow up info I saw on Vital MX.
Thank you for participating on kdxrider.net. :bravo:
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Re: 2006 CRF250 + 2004 KDX 200

Post by B737driver »

Kinda digging that silencer guard/spooge catching apparatus... :grin: good luck with the build. I’ll be tuning in for this one. :pop:
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Re: 2006 CRF250 + 2004 KDX 200

Post by bufftester »

I believe that's one of those foil hat guards that keeps the aliens and the CIA from hearing you riding :lol:
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2006 CRF250 + 2004 KDX 200

Post by Goatsby »

It's actually a collector for spooge cones! Like a snow cone, but spooge. You let the spooge collect and you then eat it out of a handy foil cone. It's very soon time to start stripping the two bikes down, I blew a base gasket on my KTM because the nuts worked themselves loose. So I'm taking care of that first.
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