KDX vs 125mx... advice?

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speedy1

Member
Jul 21, 2009
42
0
I owned a mint, stock 1996 KDX for 4 years and loved it. Then for some dumb reason I sold it :(

Now I'm trying to get back into trail riding and only have $800 to spend. I am not seeing much in that price range and am starting to consider mx bikes as they are plentyful and cheap.

Has anyone got any experience riding both a 125 and a KDX that can tell me the difference power wise? I'm not talking 2009 models here... :) more 1995-2000 vintage if possible. Preferrably CR, KX or YZ bikes.

I have read that most 125cc bikes have about the same power as a KDX, but it's just higher in the rev range.

Would a 125 with a flywheel weight behave similarly to a KDX? More torquey and tractable... better able to climb hills and such, or would it just feel weak?

Background: I rode a 94 Rm 125 once on a trail ride and it was just gutless... but I also owned a 1988 CR125 when I was younger and it seemed to have gobs of power. Not sure if my memory is fading... or if the CR just makes more power than the RM.

I have ridden a 96 CR250 and it was just too powerful. Also the 5 speed transmission didn't have good gear spacing for the tight woods riding I usually do.

I'm hoping a 125 with a flywheel weight, a spark arrestor and a set of bark busters will do the trick, but would really appreciate advice on the subject.

Please help!

Thanks :)
 
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julien_d

Member
Oct 28, 2008
1,788
1
You should be able to find a KDX in the same price range as a 125. Power wise, there's no comparison. Apples and oranges. A 125 is never going to have the low end pull of a KDX, and the KDX is never going to rip up top quite like a 125 does.
 
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mudpack

Member
Nov 13, 2008
637
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An old 125MX'er might have the same peak power as a KDX200, but it will never have the low end power of a KDX.
A heavy flywheel does not add power, it only makes a pipey engine's "hit" less abrupt. (It actually absorbs power...) It will also make the engine slightly less easy to stall...but only slightly.
It will not turn a motocross bike into a decent trail bike. Then again, your trails may be of the type that will allow you to use the peaky power of an MX bike.
If I were in your shoes, I'd keep looking (all over the country, if necessary, not just locally) for a good enduro bike.
 
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reepicheep

Member
Apr 3, 2009
670
2
I bought a 95 KDX-200 for $750. And proceeded to put close to another $1000 into it. It's pretty nicely sorted and farkled now, but as strategies for saving money go, I'd have to call it an epic fail. :)

Save more money, and buy a nicely sorted and well running 1995 or later KDX-200 or KDX-220. I have a friend looking to sell his 220 (nicely set up and ready to ride with a lot of nice extras) for $1600. Another friend bought a pretty much barely used bone stock KDX-200 for $1500.
 
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julien_d

Member
Oct 28, 2008
1,788
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I got my 89 for $400, hadn't been started in a few years. Have put about $800 into it not counting tires and stuff like that. It's turned out to be one of the best bikes I've ever owned, despite being 20 years old. I like showing my rear fender to my buddies on sparkly new KTM's and 450f's.
 
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speedy1

Member
Jul 21, 2009
42
0
I also came across a 1996 for $750, but that guy had raced it and the guy before and he didn't know any maintenance history and he hadn't done anything to it but ride it... I just didn't want to buy a ticking time bomb. Sounds like you have the same story repicheep.

Another guy let his 1998 KTM 250 exc (exc cond. 1 owner) for $800. I never thought he would consider the offer so I hesitated and then when I finally did offer it was gone.

Deals are out there I guess. I am just impatient and don't have much cash to throw at a bike... That is why I was trying to look at other options (125/250mx).
 
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speedy1

Member
Jul 21, 2009
42
0
So a 125 is just not a good bet... Are the 250 mx bikes manageable with a flywheel weight and a couple teeth smaller on the rear sprocket? or are they still untamable beasts?

I am listening and appreciate your suggestions :) I just want to make sure I don't miss any options :)
 

Patman

Pantless Wonder
LIFETIME SPONSOR
Dec 26, 1999
19,765
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I'm quite impressed with my son's CR125 on trails. Doesn't tractor like the XR284 and the gear spacing isn't nearly the same but ridden with that in mind it does a fine job. Granted it's punched out to a 134 and has been properly tuned but I fear with a flywheel weight and a little armor it could very well be a very fun trail bike.
 

Joburble

Bring back the CR500
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Jul 20, 2009
417
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If your gonna do MX buy an MX bike, if your ganna do trails buy a trail bike. A 125 with or without a flywheel weight isn't going to do you any favors when you come across a gnarly first gear turn into a steep uphill with no run up.
Ah, the things we wish we had never sold, I have a list of them.
 
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speedy1

Member
Jul 21, 2009
42
0
I found a 1992 KX 250 in excellent condition with a turbine core S/A already installed. negotiated price is $750. I think I'm going to buy it if he'll hold it for me til the weekend. A heavy flywheel weight is available for it (should make the hit manageable) and I can adjust the final gearing if need be relatively cheaply. Should work for a trail bike on the cheap. Maybe not ideal, but hopefully pretty decent for the money.
 
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sr5bidder

Member
Oct 27, 2008
1,463
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I was reading some posts were guys where getting rid of 250 2 strokes and going to yamaha 125's for the harescramble racing...I think it was thumpertalk/offroad/yamaha/ 2 stroke discussion
 

WoodsRider

Sponsoring Member<BR>Club Moderator
Damn Yankees
Oct 13, 1999
2,807
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speedy1 said:
Now I'm trying to get back into trail riding and only have $800 to spend. I am not seeing much in that price range and am starting to consider mx bikes as they are plentyful and cheap.
Click to expand...

For trail riding an MX bike I'd choose a 250 over a 125. Sure there are guys who race, and win on, 125 MX bikes in the woods, but it's a lot more work and parts wear out a lot quicker on 125s.
 
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speedy1

Member
Jul 21, 2009
42
0
Check this out :) just got the e-mail this morning

I'm going to look at this tonight... it's 10 miles away :)

I have a 1990 KDX I'm thinking about selling. It is in great condition and runs perfectly. I bought it new in 1990 and rode it summers at my parents cabin in Grand Rapids for several years. I stored it for about 10 years, and then in 2008 I rebuilt the top-end, installed new tires, sprockets, air filter. I rode it in a few enduros in 2008 and 2009. Let me know if you'd like pictures. I'd sell it for $800 - I live in Grand Rapids, MN.

I'm kinda excited... :laugh: :yikes: :laugh:
 
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speedy1

Member
Jul 21, 2009
42
0
was the 250 made in 1990? I think the only KDX made that year was a 200. Either way, it was a 200 and not in great condition... It ran well, but it needed a thorough cleaning and a few parts to make it decent. I can see paying $600 for it, but $800 even though it isn't much is too much to pay. I'm still looking.

-Wes
 
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julien_d

Member
Oct 28, 2008
1,788
1
Dunno. If it runs it's gonna be worth about that. Like I said, I gave $450 for mine NOT running. Hadn't been started in at least a few years. If you're looking for something for $800 that DOESN'T need work, I think you'll be looking for a loooong time.

Yeah the KDX250 was around in 1990.
 
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robwbright

Member
Apr 8, 2005
2,283
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I understand and agree that a 125 MX bike is not an ideal trail bike.

That doesn't mean you can't make it work. I only started racing MX about 4 years ago. I spent more than a decade of riding riding trails almost exclusively and until my recent 4 stroke purchase, my bikes have been:

1980 CR80R

1985 XR100

1986 CR80R

2002 RM125 (which my brother is currently using for woods riding and racing - he loves it because it's light and easy to manuever in tight woods).

As you can see, I've spent most of my time in the woods of West Virginia and Ohio on small bore 2 strokes. Keep the momentum going and it's not a problem. Learn to use the clutch.

That said, the KDX would be a better choice for trail riding.
 
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sr5bidder

Member
Oct 27, 2008
1,463
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agreed mine was $750 and needed nothing mechanical to run for over a year, but torn purple seat, peg springs shot and other stuff I wanted adds up and I was lucky some $800 bike can be on the verge of blowing and people lie especaily blaster owners/ sellers
 
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speedy1

Member
Jul 21, 2009
42
0
Welll... After looking at two sacked out KDX bikes... I am heavily leaning toward the very clean 1992 KX 250 that is available for $750 somewhat nearby. It's really clean cosmetically and looks like it is all there and unmolested. It already has a turbine core S/A on it so I was thinking I would pick it up and install the heaviest flywheel weight I can find and just run it. Workable? or am I being impatient and dumb...???

I have heard really good things about the flywheel weights for making the 250 manageable. I am 6'3 and 230# so the extra power might be helpful if the flywheel weight will take the angry out of the delivery. From what I hear, it will. Am I wrong?

The suspension might be a little on the stiff side, but I'm thinking that with the flywheel weight, I should still be able to get traction in the trails.

Also, I should only have $850 into it (minus incidentals, hopefully minimal) so maybe I will be able to spend a little on subtle suspension mods if need be.

Whadda you guys think?
 
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reepicheep

Member
Apr 3, 2009
670
2
I've never ridden a big KX, but if the bike is a solid runner, it can't be *that* bad at that price, especially with $200+ worth of exhaust on it.

The only other thing to check is top end intervals... to know what you are getting into. I was pretty shocked when I read my son's KX-60 service manual (an MX bike we converted for trails) and read that the top end was supposed to be replaced after every third race. Yikes.

Fuel tank size may be the other issue, but if your riding there is like my riding here, it's totally a non issue. I'm lucky to find a place to ride that will ever let us get more then 10 miles away from gas.
 
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speedy1

Member
Jul 21, 2009
42
0
I guess I'm more worried about the bike being too much to handle power wise. I really don't think it will be. Size wise, it should fit me perfectly. I have heard the KX250 of this year in particular has a relatively smooth powerband and plush suspension so I think it'll be pretty close as is.

If the midrange hit is a bit much, I'm going to put a heavy flywheel weight on it and hopefully tame it some. For the money, I have not seen a cleaner bike. and with the turbine core S/A already in place, it's one less thing I'll have to buy.

I just got a no on my (basically a lowball) offer for the last KDX in the area. So I'm pretty sure I'm going with the KX unless someone thinks it is going to be a huge mistake. I'm leaving tomorrow, let me know if the red flags are flying high :)
 
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