KDXRIDER.NET

Well I am taking the plunge in the hybrid world. I picked up an 03 KX125 for $600 and this weekend I bought an 02 KDX220 for $1200. The KDX has KX250 front end and a couple other goodies. I will be taking a good part of the riding season to build this so I will post updates on progression. The KX has been apart for a week or so and today I was able to pull the 220 motor and get it on the bench.


All the rear end bearings on the KX are shot, the chain rubbed a spot through the swingarm. I will be cutting engine mounts off the KX and doing the swingarm cutting and the case drilling. Not sure if I want to do the drilling of take somewhere. I would like to know about the swingarm cutting. I have read that 9mm each side is good. So does this mean I will not use the inside seals for the bearings? The 9mm you cut off is where those seals live. I'll keep you all updated on the progress.

You definitely use the inner seals. They just go in the same location after the swing arm is cut. You will see that there is still plenty of room there for those seals after you make the cuts. It would be best to measure your specific application for the amount to remove from the swing arm. It will likely be close to 9mm on each side, but since you can't add aluminum back, you should measure.

With all that being said, the amount you remove from the swing arm isn't as critical as what you remove from the swing arm bushings.

Nice score on getting the kx for $600

Tedh98 wrote:You definitely use the inner seals. They just go in the same location after the swing arm is cut. You will see that there is still plenty of room there for those seals after you make the cuts. It would be best to measure your specific application for the amount to remove from the swing arm. It will likely be close to 9mm on each side, but since you can't add aluminum back, you should measure.

With all that being said, the amount you remove from the swing arm isn't as critical as what you remove from the swing arm bushings.

Nice score on getting the kx for $600

Good advice. Or as the old rule goes "measure twice, cut once". You can get most any machine shop to drill the case for you. Just make sure that you mock up your entire intake/engine/exhaust before you weld any engine mounts. Much easier to sort out the fitting of the pipe, exhaust mounts, carb and airbox before hand.

I am quite capable of doing the drilling, I am just weighing out the price of all the bits vs just having someone do it. I believe there is someone on here that has the bits to loan out. I imagine going slow, lots of oil and no distractions and it should be pretty easy. I am going to be using a PC Platinum pipe that came with the bike. I have nothing to compare to it so I am going to use it.

Skippy used to pimp out the drill bits community reamer topic, he'd be the one to contact to see if they are still available. I bought the bits and they were pricey, I think I spent around $100 on the 3 bits and reamer. Lots of cutting oil and slow worked fine. You actually are only taking material off on about 15 mm on each side of the case, the center portion is hollow. I bought the bits initially because my local machine shop didn't have the metric reamer. I have sinced loaned it out and it never came back

bufftester wrote:I bought the bits initially because my local machine shop didn't have the metric reamer.

Same here. The machine shop ordered (and I purchased) the 17mm reamer. I still have it in the workshop. I think it cost me $40.

Well the motor is on the bench and the swingarm bearings are out. I do not know if you can call them bearings though. They were just rusty pieces of metal, just fell apart. also found this little issue where the chain rubbed through. I think I am going to fill with weld and grind smooth. I will probably sand blast and powder coat it silver.
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The motor is at a friends house getting the cases drilled. He has a mill and correct tools to do it right. The swing arm is being fixed also. In the mean time I did a little work myself. I thought the KDX kickstarter was a little heavy being steel and all. I have the nice short aluminum KX kickstarter so I thought why not use it. Well it does not fit. I took them both apart and they were similar, so I started filing and sanding and about half hour later I had a KX kickstarter for my KDX. I will be ordering all my new swingarm and shock linkage bearings and a small Eastwood 135 welder. I do not have any welding experience but I can learn.

Well, a little update. I am sending the cylinder out tomorrow to Millennium for a replate. I also sent them a new Weisco piston/rings. Motor is machined to accept the KX 17mm shaft. I am waiting on my brother in law to weld the nasty gouge in the swingarm. I was able to purchase an IMS 3.1 gal natural color tank. I have all my new swingarm and linkage bearings. I am planning on cutting the motor mounts off this week. Once I mock up the new motor mounts I will model up some nice ones with the Kawasaki "K" laser cut into them. I think this will add a little touch of cool to the build. I am hoping the KX air box and boot fits. I have access to a 3D printer at work, so I will be able to model whatever size and shape adaptor I need to make it fit and print it. I hope the pipe does not give me too much of a headache.

The KX airbox and boot will work, but you will need an adapter to match the larger diameter KX boot to the smaller diameter KDX carb. I used the lip from the KDX boot as an adapter (my build thread has pics) As for the pipe, mock up the pipe, airbox and motor mounts before welding anything. proper placement of the motor to allow airbox fitment and pipe fitment will determine motor mount dimensions.

I finally had some time to work on the hybrid. Just wanted to share what I am up to. I am fortunate enough to be able to draw my own parts and make my own prototypes on a 3D printer. So I have a couple motor mounts and pipe brackets made to test fit pipe and motor location before I get to welding. Once I finalize the 3D parts I will get them to the laser for final cuts. I ended up taking the crank to a local engine builder who said all is good. So knowing that I decided to buy every new seal and bearing for the motor. I was planning on putting the motor together myself but I decided to let the engine builder do it. He builds competition chainsaw motors, so he knows the 2 stroke motor way better than me. I also have a new set of black Warp 9 wheels (Thanks Jeff),(18" rear) all new Polisport plastics, will be throwing some Highway Dirtbike handguards and top clamp on. If you have not heard of Highway Dirtbikes check them out. I have the handguards on my XR and will never use anything else.I talked to a shop that helped me get a plate for a DRZ400E a few years ago and he said no problems getting a plate for this bike.

Those are awesome mounts and brackets!

thanks Ted. I could not just hand cut some tabs when I can model whatever I need and have it printed then laser cut. I need to tweak a little on the brackets, but I think I am good to go. I am hoping to have final welding done next week. I will be having the frame sand blasted then powder coated texture black. $10 for a frame at work.

It's alive. I have new graphics on the way, and the motor should be done in a couple weeks. I had to put some DOT tires on to get the inspection done to make is street legal. Once that is final the MX51's will go on. just enough legal to get to a trail.[album][/album]

Just another quick update. Motor is done and ready to go in. I printed a mount for my Trail Tech speedo. I also made a ptototype HDPE plastic skidplate. This is 1/2" (thinnest material we had) HDPE sheet plastic. The final will be all black and maybe 3/8" thick. I went to the oven at 350 degrees for about 15 minutes. this let the plastic get soft enough to bolt it in place to hold the curved shape I needed. I will finalize the design and make sure I get full engine protection and cut a new one.

Very cool!

Wow you make it look and sound so easy.

Finally finished. Started after a couple good kicks and just purrrrrs. there is a good stumble off idle but it is pretty cold here and also motor is all new and fresh. I am not going to mess with carb till we have warm weather.

Nice bike! I like the sidestand, what brand is it?

Wow! Great job! Your work has paid off for you. Nice bike.

chkdx: http://www.promotobillet.com/p-18131-kickstands.html

I think.