Some questions

[Tyler3386]

Ok, first of all, I read the faq thread and found it pretty helpful. I'm thinking about trading my quad for a dirtbike. I do ride trails but my dilemma is that my quad is fast and I dont want to get a bike that will make me dread finding wide open spaces.

I've read alot of posts saying what mods work well and how they compare to other kdx configurations but I've yet to find a post that can help me to gauge the power of the kdx as compared to other dirtbikes. My stock predator was a hair faster than a stock 2000ish cr 125. I've probably added 5 more hp with a modified carb, exhaust, and intake and like I said, I dont want to move down in the power department.

I guess my questions are how does a stock or close to stock kdx compare to a 125mx bike and what would it take for a kdx to not get "smoked" by a 250? Thank you for any responses.

 

[chris kuba]

OK, I'll throw my 2 cents in. I have read posts on this site from guys who have tracked their speed with a GPS unit and said they were running at about 70mph flat out. These guys were out west where you can do that I guess. I think they also had the "useual" mods on their bikes, pipe/silencer, piston, reeds, no airbox lid, and probably sprocket changes. All of which I have but set up for the rocks and hills and tight woods of PA. My '99 KDX 200 is as fast as any 2 stroke 125 and is far more manageable in tricky situations where you have to overrev a 125 too much. KTM has a 2 stroke 200 that is much stronger than the KDX from the factory and will eat most of the new 4 stroke 250 MX bikes. My KDX destroys all of the old style 4 strokes like the XR and DR's and easily keeps up to bigger bikes in the stuff I ride in. All in all I think the KDX will always get beat by the 250 in any drag race and isn't the fastest thing around but that's not what it was built for. Besides that there's a million things you can do to a KDX like a 225cc kit which I hear is really sweet in the power department.

 

[Crunch]

If I can remember correctly I believe the book says that a stock KDX tops out at 72 mph. Of course that depends on a lot of things, but the KDX is a great all around bike. In the tight technical stuff, it can compete with anything. The hop ups are numerous and can be targeted for what you want, but in the long straight aways, your probably not going to get much over 75 mph. But I love my KDX! At least for me it was the best bike for the money.

 

[Crunch]

Hey Tyler,
If you haven’t already you could check out Fredette Racing Products at this website: http://www.frpoffroad.com/kdxposed/engineTips.aspx
He lays out how to get the most performance out of the KDX pretty clearly. And he's been pretty successful with the KDX in competition.

 

[Tyler3386]

Ok guys thanks. I'm not really talking top speed when I say fast. I just want something that is good in trails and exciting when I can really open her up. Im definately going to keep the kdx in mind although I will probably want to find one already hopped up some if i go that route.

 

[NM_KDX200]

Well, let's see....I just bought a KX125 and have a slightly modded KDX200. Riding them both, I find that:

KX125- lighter, quicker (from point A to point B when it's a short distance), much pipier, and much less tractable, handles over-jumping better, MUCH more sensitive to throttle in the air.

KDX200- more power from bottom to about 2/3, wheelies better and easier, no slouch in point A to point B acceleration, comes out of the corners a little better but then loses to the KX, much more forgiving of throttle control.

When I first rode the KX on my track, I got arm pump really fast and lasted only about 5 laps before I had to stop and relax. I never get arm pump on the KDX and can go 20 minutes easy. Surprisingly, I didn't automatically over-jump everything on the KX like I thought I would (like I used to do on my YZ250WR), although it would certainly be possible if I wanted to. Bottom line for me is that if I could have just 1, it would be the KDX for sure. It is PLENTY exciting when I open it up, esp. with the Rev pipe. My KDX has modified suspension, FMF Rev pipe (and I have a K-35, too), ISDE silencer, and lowered gearing. The KX has modified suspension, Pro Circuit pipe, Pro Circuit shorty silencer, VF-II reed cage.

 

[adam728]

A stock KDX is much slower than a stock 125 MX bike. A decently modified KDX (pipe, silencer, no airbox lid, proper jetting, reeds) will be close to as fast as a 125. Throw some more work in there (like porting, head work, possibly big bore) and you will run neck and neck or a touch faster than a 125, but have a much more user friendly motor. I don't think there is much you can do to make it run with a 250 MX bike, unless you are talking a 7 year old, clapped out stock 250 MXer.

After saying all that I have to say this, a LOT depends on the rider. I've raced a few motos (250C) on my KDX, and do alright. The suspension hurts more than being down on power. On short start straights I can usually end up in the front half of the pack, even though I am down an easy 10 hp. On longer starts I usually end up further back, like say 30th out of a 40 rider start, for example. With equal riders a KDX will get smoked by the time you are 30 feet out of the gate.

That being said, the KDX isn't bad in open spaces. Stock my 220 was a big disappointment to me, it fell on it's face at a very low RPM. It would still keep pulling, it just didn't do it quickly. I ran 71.9 mph on a gravel road with a bike that was stock other than fork springs and dual sport lighting. Now my bike has the following mods:
FRP porting
FRP milled head and reshaped dome
FRP bored carb
FMF desert (or Rev) pipe
FMF Turbine Core 2 silencer
Boyseen Power Reeds
Cut up air box lid
Proper Jetting
13-49 gearing (13-47 is stock)

The bike is an animal compared to a stock 220, and is much more fun for me to ride (I ride aggressivly 95% of the time). It's still no MX bike, and feels like a little girls power wheel compared to a 250 or 450 MXer. Don't get me wrong, it goes pretty good, and with a little body english I can stand it up in all the gears (ok, with a LOT of body english in 6th). But I also have a ton of time and money in it to still get whipped by stockers. I promise you in a side by side drag your Predator would whip my bike. I used to be a Polaris mechanic. :)

 

[Tyler3386]

Alright guys, thats what I was looking for. The power issue is scaring me away from the kdx. I'll definately want to test ride one before I get my money out. Thanks again for your time.

 

[Green Hornet]

Let me ask you this. How fast do you plan on going in the woods?? On a straight an MX bike will get to A & B quicker, but is 60 + mph not fast enough on the dirt?? I've riden scrambles & steep mountains on my 220 and I will tell you its not stuck for power. Actually, I rode Up, Down & through a rock stream bed that MX bikes were piled & stuck in. If you ride aggresive enough the bike is not under powered. I just put the 35mm carb on my 220 and the power is smoother, revs higher and is a pleasure to ride. When I want to pounce on it, it now comes to the point if I have enough balls to go to the next step.If you ride it,it will respond. If you plan on racing MX than stay away from this bike. Also, who out there is using the full engine HP when racing or riding??? Bet not many
PS: It does have to have basic mods to have a chance though

1-Lid Free Air Box
2-Gnarly (Rev) Pipe
3-Turbine Core 2 S/A
4-Torque Ring
5-Boyseen Power Reeds
6-35mm (200) Carb w/stock 160 Main,42 Pilot & 220 Needle (1173-2nd from Top) in place of the 200 (1174)-Fredette Recommended the needle Change

 

[NM_KDX200]

2-Gnarly (Rev) Pipe

4-Torque Ring

I've been running just the Rev pipe for a little over a month now and have been very pleased except that I missed the low end pull of the K-35. Just the other day, I thought "Hey, what if I use the torque ring with this new pipe?" ;) So, I did and HEY!!! Now, if I'm in first and just putting and crack the throttle the front end IMMEDIATELY starts lifting. This is SO nice for low speed going-over-rocks and such. And it didn't hurt the top-end kick. A win-win situation. :nod:

 

[Rhodester]

You got that out of a torque ring?! Yours must be made out of unobtainium....

 

[Tyler3386]

Yea I understand the thing about not using all fo the power in the trails on most any bike or quad. I think id rather have too much power than to be wringing its neck all the time though. Im sure the mods are very worthwhile on the kdx which would make it fun.

 

[kx200]

the main thing is to get off the (poop wheeler) quad :)

 

[Green Hornet]

the main thing is to get off the (poop wheeler) quad :)

AMEN

 

[Tyler3386]

I really like my pred but I think I'm ready for a change. I wont be able to do as many things on a bike (night riding maybe, girlfriend riding with me, snow) but I hope it will be funner.

 

[bcVulcan]

I think id rather have too much power than to be wringing its neck all the time though.

Unless your a very experienced BIKE rider, you won't be "ringing it's neck". It might ring yours. ;)
Just going to a bike, you'll enjoy this bike more than any other IMO.
Good luck.

 

[Kav]

I wont be able to do as many things on a bike (night riding maybe, girlfriend riding with me, snow) but I hope it will be funner.

Well if you get a KDX, you can ride at night. (they've got a good head light, so you can avoid the flashlight-taped-to-the-fender-commen-sence-lacking-stunt I tend to pull.) If you're brave enough snow/ice riding is not out of the qustion. you can get tire screws for that. But riding with the GF isn't going to happen. Looks like she'll need a bike.

Over all you may find you can do more on a bike then on a quad

 

[NM_KDX200]

You got that out of a torque ring?! Yours must be made out of unobtainium....

Mine's actually just a gasket from a CBR600 (I think...). All I can tell you is that it sure pulls good from down low.

Just got back in from riding the new KX. I like it!