KDX250 KX250 Hybrid thoughts & opionions?????????

Discussion for swapping a KDX motor in a MX frame...
BIG-B
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KDX250 KX250 Hybrid thoughts & opionions?????????

Post by BIG-B »

Hi all, I have been learking for awhile and need some thoughts and opionions on building a 2001 KX250 hybird for a duel sport/ woods bike. I bought a KDX250 engine with the intent to do a trans conversion on my 01 KX250, but now Im thinking of putting the entire KDX250 engine and trans in my bike (along with a few other mods). What does anyone think??????? What would you do??????
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KDX250 KX250 Hybrid thoughts & opionions?????????

Post by ecojbr »

I am looking for a kdx 250 motor to do the same. I love my 200 hybrid, but would love to see how the added low end grunt would be. If you finish yours first, please let us know
04 kx220 hybrid
03 kx 250
05 kdx 200
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KDX250 KX250 Hybrid thoughts & opionions?????????

Post by SS109 »

Well, I think it is no secret that I absolutely love the KDX250 engine and will be putting mine in an '06 KX250f chassis. I say go for it and post up some video of you riding it! OK, now being more practical, the KDX250 is getting harder to find parts for and I'm sure it will only get worse. The trans swap might be the better choice in the long run. Me, I'm sticking with the KDX engine! :mrgreen:
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Re: KDX250 KX250 Hybrid thoughts & opionions?????????

Post by ecojbr »

Anyone gotten anywhere with this yet? I am looking for the ingredients for this one also.
04 kx220 hybrid
03 kx 250
05 kdx 200
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KDX250 KX250 Hybrid thoughts & opionions?????????

Post by SS109 »

Eh, life has gotten in the way of getting mine done. Hopefully I'll be able to get started before too much longer.
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KDX250 KX250 Hybrid thoughts & opionions?????????

Post by rmz480mx »

Hi, I have a 2003 KDX 220 and I want to swap out jugs and cylinders to get a 250cc. Has anyone done this? Is the jug the same (I think it is) I am concerned about the stroke.. etc any inputs are greatly appreciated
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KDX250 KX250 Hybrid thoughts & opionions?????????

Post by scheckaet »

there is no such thing as an 03 KDX 250. and no nothing will bolt on from other kx/KDX years
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Re: KDX250 KX250 Hybrid thoughts & opionions?????????

Post by rmz480mx »

I see that the jugs are different between the 03 KX 250 and 03 KDX 220> I guess I will just bore the 220 any thoughts?
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KDX250 KX250 Hybrid thoughts & opionions?????????

Post by scheckaet »

no, bore the 200 to 225.
unless you want go higher than 225 and run a sleeve (might consider riding a different bike then...)
Do a search on 225 conversion...
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Re: KDX250 KX250 Hybrid thoughts & opionions?????????

Post by SS109 »

rmz480mx wrote:I see that the jugs are different between the 03 KX 250 and 03 KDX 220> I guess I will just bore the 220 any thoughts?
Not worth it. If you want a 250, buy a 250. Boring a 220 out that far would require the removal of the power valves and they are one of the great things about the KDX engines.
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KDX250 KX250 Hybrid thoughts & opionions?????????

Post by scheckaet »

'zactly!
the max i believe is 225 if you use the 200 jug (the 220 has different porting and boring it out makes it weaker or something, do a search and u shall find)
http://www.eric-gorr.com/bbmasterlist.php
KDX200 1995-2006 225cc $500
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KDX250 KX250 Hybrid thoughts & opionions?????????

Post by rbates9 »

I can't find it now but I have seen a place I think out of MA that will bore and stroke a H series engine out to 250cc with power valves intact. They grind out the case and did something with the crank to get a longer stroke plus a bigger bore. But it cost somewhere around $5-$6K so it is not worth doing. Start with a $1500 bike, add a $5000 engine and end up with a $1600 bike. :doh:
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KDX250 KX250 Hybrid thoughts & opionions?????????

Post by ecojbr »

Clean up the ports in your 220, add 200 carb, and tighten up the head. 220's need and like compression before you give up on it. Just Imade my 200 a 220 and like it lots better. I even got 8.3oz off my flywheel. I love it, most will say it loses low end chugability, few have even tried it,I love it
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KDX250 KX250 Hybrid thoughts & opionions?????????

Post by rbates9 »

How did you lighten your flywheel? Did you turn it down on a lathe?
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Re: KDX250 KX250 Hybrid thoughts & opionions?????????

Post by ecojbr »

Yes, cut off some of the outside, some where the puller goes, some of the inside of the hub, it's hard to get that much off, but doable, I have two lightened now. 8.3 is about all that can be trimmed safely imo. I haven't noticed any low end changes, just a little faster rev, nothing mx like, but a very noticable increase
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KDX250 KX250 Hybrid thoughts & opionions?????????

Post by SS109 »

Even though my 200 has plenty of power, I just wouldn't give up any weight from the flywheel. I ride some hike-a-bike stuff sometimes and need that weight.
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'11 GasGas EC250R
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KDX250 KX250 Hybrid thoughts & opionions?????????

Post by ecojbr »

Thought I had everything found, had an 04 roller lined up, then the kdx 250 seller backed out :-( I am dying to try this build
04 kx220 hybrid
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05 kdx 200
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Re: KDX250 KX250 Hybrid thoughts & opionions?????????

Post by hybridracing65 »

If you want bigger you can take the 200 out to 225 or 240 through Eric Gorr. He does a great job as i have a 225. For tight stuff you are better off with a 220 with the Ron Black head and Carb mods and a desert pipe. The ports are differnt on the 220 cyclinder than a 200 and overboring the 220 really does not give you any gains. At least not as good as the Ron Black mods for the cost.

KDX250 to KX250?
Why?
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KDX250 KX250 Hybrid thoughts & opionions?????????

Post by ecojbr »

Big bore would never have the torque of a 250. The purpose of this build is to get the amazing torque of a 250 without the arm ripping hit. Although I must say my sons 250 with 13oz weight, rekluse, and fmf pipe is getting real close to being as easy to ride as my hybrid, just to dang hard to start with my short legs.
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KDX250 KX250 Hybrid thoughts & opionions?????????

Post by SS109 »

Then find a KDX250 or get a KX250 and have Eric Gorr port it for more low. Tell him what your after and he can help make it happen. Between port work and a FWW you will have your torquey 250 without the brutal hit.
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