99' KX / 03' KDX Hybrid build......

Discussion for swapping a KDX motor in a MX frame...
dfeckel
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Post by dfeckel »

Looks fantastic. You'll love it.
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Post by bulabula09 »

...WOW!...thats all i have to say...wish mine looked that good...im def gonna try to polish the swing arm...that really makes it pop. EXCELLENT JOB MAN!!! :prayer:
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Post by Coop »

Very nice!
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2003 KDX200
HRDROKN
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Post by HRDROKN »

Thanks for the comps guys!

So I did have a chance to get out and ride this last Sunday. I can say it’s good and not so good….

The balance of the bike is great, definitely “feels” lighter than the KDX (not sure what the weight reduction actually is), easier to ride through the technical stuff than the KTM. As I made each consecutive loop I found myself less concerned with my lines, so it would seem that the suspension is at least in the ballpark.

With the RB carb mods, I have the 1/8-1/3 throttle bog when whacking the throttle with the bike on the flat… tried some different known setups including what RB sent without a cure at this point. On the trial when the motor is under load the bog does not exist… other than she feels just a tad lean, but even with that she would pull from virtually nothing to WOT without complaint. I would say that the head mods have really strengthened the low to mid torque, making the bike super nice in the technical stuff.

I have some jetting to get sorted out (after hand surgery that is) and have several things to try based on what others have found.

Currently:
PJ = 40
AS = 7/8 – 1.5
Slide = #7
NJ = JD red #5
MJ = 152

Image

Image

Image
HRDROKN
00' KTM 300exc (sold)
99'/03' KXD Hybrid, ****'s Racing Susp, RB carb / head mod.
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Tedh98
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Post by Tedh98 »

I don't have an RB carb, so I'm basing this on what I think I remember reading. But the AS should be out a lot farther than a regular carb, something like 2 1/2 turns out.
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Indawoods
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Post by Indawoods »

That's to hit the SSS....
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Post by ihatefalling »

Awesome build dude......Congrats on all the hard work :supz:
2005 KDX 220
R&B Carb Mod
R&B Head Mod
Fork Swap - 99 KX125 Valved for B woods plush
FMF Gnarley
Airbox Mod
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Post by HRDROKN »

>|QBB<[/url]
ihatefalling wrote:Awesome build dude......Congrats on all the hard work :supz:
Thanks!

If I had thought of it at the time.... I should have welded a mount for this KX100 kickstand to my frame, before I powdered it that is! Just something to keep in mind for future hybrid builds.

Image

:rolleyes:
HRDROKN
00' KTM 300exc (sold)
99'/03' KXD Hybrid, ****'s Racing Susp, RB carb / head mod.
UFS207
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Post by UFS207 »

Could you go into a bit more detail on your exhuast setup? I have a similar build (01 kx125/00 220 motor).
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Post by HRDROKN »

>|<>QBB<
UFS207 wrote:Could you go into a bit more detail on your exhuast setup? I have a similar build (01 kx125/00 220 motor).
Any particular part of it?
HRDROKN
00' KTM 300exc (sold)
99'/03' KXD Hybrid, ****'s Racing Susp, RB carb / head mod.
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Post by UFS207 »

Thanks for responding. I work nights so forgive my late reply. I went back and re-read your thread and from what I can gather you are using a FMF Gnarly "woods" pipe and the KX125 turbine core 2 with KDX internals. Is this right? I'm guessing the "KDX internals" are from a KDX FMF turbine core 2 arrestor? Did you have to heat/bend the Gnarly pipe around any to get it to fit correctly? Did you end up denting it to get it seat fully?

I'm just trying to get a good handle on what will work best (least amount of hacking/moding) before I buy new. Any help greatly appreciated. SWEET looking bike BTW, mine looks like a true rat bike at this stage....I can't wait to start stripping it down to address the cosmetics.
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Post by HRDROKN »

>|<>QBB<
UFS207 wrote:Thanks for responding. I work nights so forgive my late reply. I went back and re-read your thread and from what I can gather you are using a FMF Gnarly "woods" pipe and the KX125 turbine core 2 with KDX internals. Is this right? I'm guessing the "KDX internals" are from a KDX FMF turbine core 2 arrestor? Did you have to heat/bend the Gnarly pipe around any to get it to fit correctly? Did you end up denting it to get it seat fully?

I'm just trying to get a good handle on what will work best (least amount of hacking/moding) before I buy new. Any help greatly appreciated. SWEET looking bike BTW, mine looks like a true rat bike at this stage....I can't wait to start stripping it down to address the cosmetics.
Only mod to the pipe was to cut off the factory lower mount and weld on a new mount tab with a rubber issolator from McMaster-carr. I didn't have to dent, bend or add to the pipe... remember that my motor is a little further forward than other builds.

You got the idea on the silencer.... just combined the FMF KDX with the FMF KX. Then I had to remove about 4" off the stinger to adjust for length. You can see in the pics that I cut the middle pipe section out of the stinger, shortened, rotated for fit and weld. The KDX stinger has a mount bracket that also gets removed.

I've read that many have had luck with the KX250 silencers... I was just trying to utulize what I had on hand.
HRDROKN
00' KTM 300exc (sold)
99'/03' KXD Hybrid, ****'s Racing Susp, RB carb / head mod.
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99' KX / 03' KDX Hybrid build......

Post by HRDROKN »

:supz:
HRDROKN
00' KTM 300exc (sold)
99'/03' KXD Hybrid, ****'s Racing Susp, RB carb / head mod.
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