KDXRIDER.NET

I'm on the edge about wether or not I want to do the swap to a mx frame. I just took my kdx out on it's first ride (bone stock) Saturday and I love it. But with with winter pretty much here or close. I want something to tinker with. What year kx frames are the best for the H series motors? Reason I ask is becase I came across a 01 kx250 for 700 bucks. Or are the 125 frames a little better? Or should I see if I can find a 06+ frame? I'm in no rush to swap the motor since the kdx runs and rides good right now but i just want to know what's the best frame just in case I come across one for cheap.

Thanks
-Zac

Skip the 250’s and stick with steel frames.

So what year steel frames work best?

2004-2005 are pretty straight forward.

2003 was an oddball year, I would stay away from it.

2002 and older are pretty simple as well.

Does it matter if it's either a 125 or 250?

Stick with the 125’s. The engine cradle on the 250 is too big.

I'd swap a better set of forks onto the KDX and call it good.

I came across a 94 kx 125 for 250 bucks. Should I hop on that or get a 99-02?

For parts availability I always go with the newest I can get - but that is just me.

FYI, I'm pretty sure the 125s are sprung and valved softer than the 250s. Something to consider based on your weight, riding style, etc. I used to have a CR250 and I found the stock valving very harsh off-road.

Something else to consider is that the '03 and up KX's, IMO, the handling is sub-par to the '96 to '02 models. They changed the offset of the triple clamps from 22mm to 25mm on '03 and up and, in '03 only, they removed the high speed compression from the shock. The '99-'02 shock will fit the '03 chassis so that's a fairly cheap and easy fix. The triple clamps are another story.

The 25mm offset causes some weird handling quirks with the front end trying to knife and push, back and forth, with no predictability or reason. Do some research on the net about this on the '03 and '04 bikes. The '05-'07 bikes were better but even they work better with 22mm or even 21.5mm offset. Anyway, in '02 the KX's switched from 46mm to 48mm KYB forks. So, only the '02 stock clamps have the better 22mm offset and will fit the '03-'04 KX's if you swap stems (I'm not sure if they'll fit the '05-'07 bikes) and they are about impossible to find. That only leaves the aftermarket for triple clamps that fix the problem and they tend to cost around $450+.

Lastly, the KX125 chassis is lighter than the 250 version. There is not 25lbs difference between the 125/250 emgines yet that is how much difference there is between the two bikes. Go with the 125 version FTW!

EDITED to add in info I forgot about the stem length

2003 stems are 6 mm longer than the 2002 on back to whenever. The head tube is 6 mm longer.

Wow... thats some good info... pretty interesting, nice research

Jason wrote:2003 stems are 6 mm longer than the 2002 on back to whenever. The head tube is 6 mm longer.

I forgot about that but swapping the stems will fix that issue.

I have another question. I came across two kx125s for 400 bucks. One is a 98 and the other is a 99. Would they be worth it to swap the kdx motor into?

Both would be good candidates for a hybrid.

SS109 wrote:Both would be good candidates for a hybrid.

awesome. thanks for the response....unforunatley they sold before i could get them. but i did come across another 99 for 300 bucks 3 hours away. so hopefully ill be able to snag it up. id like a newer kx but ill take whatever i can get at the moment.

99 - 2002 are the same except forks on 99 are 48mms as opposed to 46mms on others. I had great luck with my 02 125 chassis

Agree on the 99-02, I used an 01 125 frame with an 99 250 front end. As mentioned, the 03 was an oddball year, the 04-05 are good candidates with lots of aftermarket stuff still available. I agree with SS109, the handling on the later bikes with the larger offset made the front end hunt pretty bad (the older ones do it as well, just not as badly) and they didn't track like the KDX does. A steering stabilizer helps. Whichever way you go you will have to drill out your KDX motor swingarm pivot location which means to go back to a KDX frame you'd need a custom bolt spacer (but why would you want to go back?)

frankenschwinn wrote:99 - 2002 are the same except forks on 99 are 48mms as opposed to 46mms on others. I had great luck with my 02 125 chassis

2002 had 48 mm fork tubes. There were several small changes between 1999 - 2002 models.