Hybrid Plunge

Discussion for swapping a KDX motor in a MX frame...
hybridracing65
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Hybrid Plunge

Post by hybridracing65 »

I have wanted to build a hybrid forever so finally took the plunge.
Just finishing up MY 98 KDX220 with RB Designes head and Carb Mods and installed in a Honda 03 CR125.
Fits like a glove.
Will post picks in a day or two.
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Tedh98
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Post by Tedh98 »

Awesome, can't wait to see the pics.
hybridracing65
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Post by hybridracing65 »

Finally some pics.
so far its working good not great. I used the cr250 pipe and itneeds a few tweeks. Mayjust install the FMF .

Image[/img]

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SS109
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Post by SS109 »

I like how you went with black plastics and just added green in the graphics to let everyone know it's a Kaw at heart!

Man, that pipe looks like it is really hanging out there.
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Old KDX: '90 KDX200 -White/Blue
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David_L6
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Post by David_L6 »

That's cool! :supz: Of course I'm kinda partial to CRs (have two 250s). Do you have any pictures of the build in progress?
2000 KDX200 / 2002 CR250 / 2003 CR250 / 2008 TT-R230 / 2011 Brute Force 750 / 2012 Brute Force 750 EPS
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Post by David_L6 »

>|<>QBB<
hybridracing65 wrote:Finally some pics.
so far its working good not great. I used the cr250 pipe and itneeds a few tweeks. Mayjust install the FMF .
I imagine the CR250 pipe is all wrong for a KDX220 motor. Which FMF pipe do you have?
2000 KDX200 / 2002 CR250 / 2003 CR250 / 2008 TT-R230 / 2011 Brute Force 750 / 2012 Brute Force 750 EPS
hybridracing65
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Post by hybridracing65 »

yes the pipe should be a rock dinger for sure! lol

I have the Gnarly desert as this is a 220 motor. it is cut and installed now. will add a pick.
you would be surrised the kx pipe is not far off a kx250 so the cr is close.
The diameter of the pipe is about an inch larger in the header. it actually runs like a bone stock kdx with this pipe, just a little stronger.
the problem is the FMF works so good it is what i wanted back on after running it in my kdx.

will see if i can scrounge up some build pics.
Very simple to do. in some cases easier then the kx.
The radiators and pipe were the hardest things to do.
when i drilled out the swing arm case bolt hole to 17mil and put the motor in the frame the original bottom motor mount bolt lined up.
unbelievable.
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Post by factoryX »

Okay, sorry to bug you but I believe I am about to take the hybrid plunge with an 02 cr125, and I am somewhat new to this.
List of questions:
1. For the swing arm, all I have to do is drill out the hole(cases) to 17 mm?
2. what exactly did you have to do with the radiators?
3. I'm not to worried about the pipe, or welding in new front mounts, or cutting the head, but is there anything that needs attention?
Any info would be great, and if anything build pics would be cool. - Malcolm
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hybridracing65
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Post by hybridracing65 »

>|<>QBB<
factoryX wrote:Okay, sorry to bug you but I believe I am about to take the hybrid plunge with an 02 cr125, and I am somewhat new to this.
List of questions:
1. For the swing arm, all I have to do is drill out the hole(cases) to 17 mm?
2. what exactly did you have to do with the radiators?
3. I'm not to worried about the pipe, or welding in new front mounts, or cutting the head, but is there anything that needs attention?
Any info would be great, and if anything build pics would be cool. - Malcolm
most of my build pics were on my phone and i have have not got those off yet, still trying.

engine cases require drill out to 17mm and you will have to shave the swingarm bushings a little or basically flush with the swingarm. The nice thing is the swingarm does not rquire any cutting.
I had to raise the CR radiators about 3/8 of an inch. i used the DR-D lowering tabs for a crf250 but in reverse.
The reason to raise the rads was i used the stock honda radiator configuration so the crossover hits the motor.
if i did it again i would mod the CR rads to match the kdx configuration for flow.
you will need the TEE from a cr250 for your return line if you use the stock CR rads.

I used the kdx carb boot and made an adapter to connect it to the cr airbox.

The only engine mount that needed modification was the front motor mount as the bottom mount and engine mount lined up nicely. :shock: :grin:

Very tight clearance at the front of the frame so i sanded and smoothed all the welds so the engine and powervalve cover does not touch the down tube.
I also used the stock KDX kick lever, as much as i hated to, it fit nicely.

Other then that it went as easy or easier then a kx build i helped a buddy with.
My longest part was finding someone to weld alluiminum for the front engine mount.
The KDX pipe fitment went easier then expected. will try to post whatever pics i can find this aft.

Hope this helps!
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Post by factoryX »

Awesome. Try texting them to your email.
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justinswrx
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Post by justinswrx »

How did you drill the case ot to 17mm? Did you use a drill bit or reamer? Im trying to figure out the best way to do this.
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Post by scheckaet »

reamer should be used.
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Post by justinswrx »

Can the reamer be used in 1 step? Are reamers tapered enough to go from a 15mm to 17mm?
hybridracing65
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Post by hybridracing65 »

>|<>QBB<
justinswrx wrote:Can the reamer be used in 1 step? Are reamers tapered enough to go from a 15mm to 17mm?
I used a couple of drillbits to step up to the reamer and finished with the reamer.
But i used an 18vlt hand drill and lots of patience.
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fuzzy
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Post by fuzzy »

Awesome!!
'91 KDX 200 Project $300 KDX
'95 KDX 200 Project $600 KDX
'94 WR 250 Always a project
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kdub405
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Post by kdub405 »

Sweet bike!!!!
Ride on
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Julien D
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Post by Julien D »

Really nice work, I like it!
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Tedh98
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Post by Tedh98 »

This is the REAMER I bought through the machine shop, you can see that it isn't designed to remove a lot of material.

I bought this COOL DRILL BIT from a guy on eBay. It is pretty neat how the tip is set at 15mm to help guide the bit through the case and then steps up to 17mm to make the cut.

He said he had a few custom made when he was doing a hybrid, so you may want to search there to see if he is still selling them. I think I paid about $10 plus shipping. I haven't used it - yet.
hybridracing65
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Post by hybridracing65 »

Thanks for the compliments
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Post by hybridracing65 »

>|<>QBB<
Tedh98 wrote:This is the REAMER I bought through the machine shop, you can see that it isn't designed to remove a lot of material.

I bought this COOL DRILL BIT from a guy on eBay. It is pretty neat how the tip is set at 15mm to help guide the bit through the case and then steps up to 17mm to make the cut.

He said he had a few custom made when he was doing a hybrid, so you may want to search there to see if he is still selling them. I think I paid about $10 plus shipping. I haven't used it - yet.
I used the very same reamer but was afraid i it would be too much to start with.
The reamer actually went through like butter, much easier then the drill bits
Thats an Interesting drill bit you purchased.
Hope it works good
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