2002 KDX/CR Hybrid build

[sixstringsteve]

Here's my build thread for my '02 CR125/KDX Hybrid. It's a 2002 KDX 200 motor transplant into a 2002 CR125 chassis. Should be a fun project.


I've had this 2002 KDX for a little over a month now. It's a fun bike, but these bikes aren't famous for their front forks. Rather than do a fork swap, I figured to do a motor swap into a nimble bike with great handling and suspension, a 2002 CR125.

Here's the KDX (ignore the dirty garage)

Last week I sold my Yamaha XT225 and bought this 2002 CR125 that's hardly been ridden.

 

[sixstringsteve]

I started out by tearing down the CR.

I was surprised that the KDX pipe doesn't bolt on like a CR. The KDX is just a pressure fit with the spings.

 

[sixstringsteve]

And here are some pictures showing the flow of the CR radiator:

 

[sixstringsteve]

Getting closer.

And just in case I dumped this over, here's a list of all the bolts and where they go:

Swingarm removed

Engine finally removed:

 

[sixstringsteve]

Now on to the KDX teardown. I really wish I had thought to wash it before I tore it down. Oh well.

KDX radiator layout:

 

[sixstringsteve]

KDX wiring in case I forget:

Getting closer.

engine is out.

 

[sixstringsteve]

Now let's compare swingarms for basic dimensions:

KDX swingarm mounting width (in mm):

CR swingarm mounting width (in mm):

KDX engine case width (in mm):

So I need to shave about 5mm from each side of the CR swingarm (and bushings too) to match the KDX engine.

 

[sixstringsteve]

Trimming the CR swingarm bushings.

Here you can see how I cut them flush with the swingarm.

Remarkably, they turn out to be 47mm, just like chopper said.


Here I am sizing up the uncut swingarm to the KDX engine. Looks like sprocket alignment won't be a problem as long as I keep the swingarm centered.

 

[sixstringsteve]

Next step is to trim down the swingarm ~5mm on each side to clear the engine case. I just used a flap disc on my angle grinder.

Here you can see that you have a few MM you can take off before reaching the inner swingarm seal.

here it is after sanding. I should have put something in there, now I have a ton of aluminum shavings inside my swingarm needle bearings. I'll have to find a good way to pull that seal out, remove the bearing, and clean it all up.

and the other side:

perfect fit.

and the sprocket is perfectly lined up.

 

[sixstringsteve]

I got the engine cleaned up:

and took the frame down to the car wash. And this is where I ended last night:

I really need to find a reamer or a 17mm drill bit so I can get crackin on this.

 

[Rot Box]

Excellent thanks for sharing the build here

Be sure to keep the overflow bottle (coolant) from the KDX. They are nice to have imo.

Can't wait to see more!

 

[TJDukit]

Awesome build Steve looks like it should be done fairly soon. Can't wait to see it done on person.

 

[rholbrook]

I sure wish I lived closer. I would love to be your gopher on this build

 

[sixstringsteve]

I sure wish I lived closer. I would love to be your gopher on this build

You and me both Russ. I have never even changed the oil on a bike before, so I have a ton of simple questions. Andrew has been getting random phone calls about little things like how to remove a throttle cable from the slide, etc. So if anyone sees any major things that I overlooked, don't second-guess me, I'm sure I overlooked it. Any tips/pointers along the way would be more than welcome. I appreciate the help guys!

 

[Marsh99]

My favorite thing about you Steve is you always make your projects unique

 

[jeeper]

What are you doing with the motor from the CR?

 

[YOUKNOW]

As I told you on Saturday, that frame is beautiful! Good find!

 

[sixstringsteve]

What are you doing with the motor from the CR?

I'm selling it. You know anyone interested? I'd be surprised if it had more than 25 hours on it, ridden sparingly by the PO's wife. I have a video of it starting first kick, just so I could prove it ran. I have the motor, fmf fatty gold pipe, titanium2 silencer, and mikuni carb for it.

 

[sixstringsteve]

Rick lent me his 43/64ths drill bit today, and it worked out perfectly.

I got the swingarm bolt, swingarm, and rear motor mount installed. That's a milestone. I had to trim the swingarm bushing just a bit more. I'd guess I ended up with 45-46mm for each bushing.

 

[sixstringsteve]

after I installed the swingarm, I took the frame and engine down to MikeGyver for him to weld on some new front motor mounts.

When we got there, we realized the engine wouldn't rotate down enough to clear the exhaust. It was hitting the front motor mounts. Even after we cut the front motor mounts, we realized the head would contact the front of the frame. Since I needed the exhaust to clear, the only option was to knotch the frame.

I apolgize for the cell phone pics, I didn't bring my camera with me to Mike's place.