'00 KDX engine in '01 KX 250 chassis?

[bmonnig]

Guys,

    I own my '00 KDX 200.  It's still above my skill level, but I love to tinker with stuff.  Also, it's no secret that as I advance I'll find the KDX's suspension/frame technology to be a barrier.  Not an issue now, but just looking ahead.  I've got a line on an '01 KX 250 that can be had for a good price.  It was raced for a season, but it still in good shape.

     So...the question becomes...what would I have if I put the KDX engine in the KX frame?  I'd have great suspension, good chassis, good usable power, etc.  Wouldn't it be the ultimate trail bike?  A KDX with current tech frame and suspension?  I know I'd be sacrificing tank size (can buy KX enduro tank), and I'd be gaining MX grade suspensions for playing on the track/rough stuff.

     To reiterate, neither bike has an issue.  They're both in good shape, so I'd have an '01 KX 250 engine and an '00 KDX 200 rolling chassis to sell after the conversion.  I would think I could have the hybrid for little more than what I paid for the KDX, after parts are sold.

     I'm not in a big hurry.  I know it's the "rider not the bike".  I know I don't need an MX-er for my skill level and desires.  I know I don't *need* this conversion.  But it'd be a fun project, keep me occupied, and should result in a great bike bike...shouldn't it? 

     Or...am I stripping the KX frame of power, and stripping the KDX engine of it's "meant for trail" frame?  Most of you guys are more experienced that me.  Let me have some feedback, here.

Thanks!

Brandon

 

[limitless]

Jeff fredette does this! It looks really nice, but it is really expensive. fredette said "If you have to ask you probably can't afford it"

www.dirtrider.net/justkdx - more info here!

 

[bmonnig]

     I'd be doing the mods myself as I'm a cheap *******.  :)  Engine mount tabs, pipe fitment, chain/sprocket aligning, swingarm/engine fitment, etc.  I'd be curious to take some measurements on the 250 engine and see just how close everything comes to bolting in.

     What I'm really looking for, though, is "what would the end result be?"  If it's a total waste of time I won't bother, but if it would produce a great chassis (KX) with the KDX power I like (KDX engine)...I think it would be fun.

     Of course, part of me says I should just buy the KX, put a FWW on it, buy an enduro tank, and sell the KDX.  I'm just looking for the most bang for my buck.  I think I can have the KX 250 or KX/KDX combo for about the same money I've already spent on the KDX (after selling of extra parts and/or bike).  

     How would an '01 KX 250 behave as a woods bike?  Did the "strangled KX" begin with the '02 model, or is an '01 a "weak" bike too?  Do we have anyone that can do an '01 KX 250 to '00 KDX 200 comparison?  Looking for mostly woods/trail riding, but the bike might be going to CA with me.  In that case, we'll have desert/dune riding as well.  MotoX tracks are awful fun too, although no formal racing will occur.  

     I'm just kind of fishing for thoughts/comments on the idea.  I hesitate to post this to the "what bike should I get forum" because I think I might get a lot of results from Moto-X'er saying "GET THE KX!".  I think the trail/recreational riders here would have a better feel for my use.   

Brandon 

 

[Ernie Estes]

I believe you would be better off putting some flyweel wt. on the KX, along with a torque pipe and any other mods that would tame the beast.(lower compression or maybe a new reed valve system) This would be much less expensive, easier to do, and be more competitive.

 

[limitless]

I don't know personally wich would be better but the kdx engine in a KX looks awseome and just sounds lie a good idea to me. The cost wouldn't be to bad if you already have the bikes and do the work yourself. Call fredette and talk to him about it... I'm sure he would be willing to give you some good pointers on performing the mods. He could prolly give a guesstement on how much your looking at spending. Let us know what you think of it if you decide to do it!

 

[Studboy]

Either way would be awesome but it would be cheaper and just as good (if not better) to get a FWW and have Eric port the bike to be like a KDX but with more OOMPH, that and with some suspension mods (necessary anyways) I think you would have an awesome bike. But, the KDX engine in the KX frame WOULD be original! :)

 

[JCW]

They are totally different bikes. It depends on your skill level and the terrain you ride. Unless you are jumping or riding the woods in 3-4 gear, the KDX would be a better choice in my opinion. I rode KXs for years and I love them. However, they are made to go fast, period. Unless you are good enough the keep the throttle open you will fight a KX in the woods. I would keep both bikes and switch back and forth and decide what you like about each bike. The obvious reason to switch is suspension. I wonder if you could switch the triple clamps and get the KX forks on a KDX. That would seem to be a lot easier than making an engine mod & frame change. I assume the rear shock could be switched out also depending on the length difference (if any). If you ride a KX in the woods, go up (add) one tooth on the countersprocket and it will smooth the bike out and give you about 10 mph more top end for about $20. Just a few thoughts. Good Luck!
JCW

 

[MR. V]

I put a '85 200 motor in a '99 kx 125 chassis. On one hand it was worth the effort. it wieghs 208lbs and handles like a dream. It was buuilt for my wife and itt suits her better than anything on the market. There are many things I needed to figure out that are not ideal for that combo. custome intake and air boot, different carb and the jetting pains that go with that. Making the exhaust fit, cuting the rear of the motor to fit at swingarm, different axle dimension, re-shaping gas tank for engine clearance, new placement of ignition boxes, kick starter modification. on mine I had to change location of exhaust port to clear frame. Your combo may not be so tough since they are closer matched in years. water cooliing may not be an issue or maybe it will. I did another bike that was a KTM 550 2 stroke motor in a 2000 YZ 250 chassis. The amount of work was rediculous. more wrenching than riding. The first time will be a bitch and you will see places you could have done better. But is unlikely you will do the exact same project again. There are two major problem area's that are alway's underestimated. Intake and exhaust. Ofcourse engine alignment is critical. If you were putting it into a 125 chassis, that could possibly bring some satisfaction with the aggrevation. It is much nicer to be able to buy parts that wear out then to have to make them or repair them. If you like the 250 chassis I would think that converting the motor is way better.

 

[Kawierider]

Mr V...
Id jsut like to say......your my hero!!!!
oh....If you ever want to sell the bike give me an email. Im there
[email protected]

 

[Speedy]

Hey Mr. V!! Do u have any Pics of that 85 motor in that 1999 kx 125 frame??