Maintenance & Technical > KX250 / KX125

2003 kx125 for wife, porting, suspension mods

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megad:
I'm setting my old 2003 KX125 for my wife

1st problem, the bottom end power does not exist, so I need to fix this first, any suggestions for who to send it off to, to get ported?   I tried a couple pipes, and I have a 9oz flywheel weight on it, with stator in bottom end position still just cant cope with big hills without lots of clutch action that my wife will have a hard time with  it needs a LOT more bottom, and the hit needs to be removed.

2nd revalve, I'm pulling the compression stacks tonight to reshim, anyone have a shim stack they would like to share with me, for trail riding?

3rd lowering, I was going to get lowering links, what exactly does one do with the forks, cut the spring and put in a longer anti bottom rubber stopper? where to get those? 

4th the power hit, it's WOW, no turning if your in the power, it hits way too hard for a novice, any adjustment I can do to the power valve to tame that?  Or will engine porting be enough?

The Flyin Hawaiian:
There is a similar post about making a 125 into a woods bike. Pretty much the same suggestions:
Gnarly pipe
V-Force or Boyesens
Re gear
A spark arrester will smooth the hit
You may be able to preload the power valve governer spring with shims to slow the opening of the p/v. It will be less violent. I did this on one of my KX250s and it smoothed the power considerably. This is a mod for the KX 250 but I dont see why it wouldnt work on the 125.
My girlfriend rides a 03 and 04 KX 250 2t and we had both of them revalved and lowered. They basically put in a spacer that restricts full extension of the fork/shock. 1" spacer = 2" in seat height.

megad:
I've done most of that already, I'm just gonna unhook the power vavle

for fork valving I"m going to try this shim stack, flip the end cap over, and run

15x14, .15x16, .15x18, .10x20, .10x14, .10x22, .10x24, .10x14, 2-.10x24.  and 100mm 5wt oil


bike already has a quiet muffler/spark arrestor, vforce3, 9oz weight, timing advanced


can anything at all be done with porting to fix the lack of bottom end on this motor? it's pretty much all high rpm power

The Flyin Hawaiian:
I would think that some low end power could be had with proper port work, but I dont think it could be turned into a tractor. Have you given any thought about a big bore kit? I mentioned in the other post about the Athena 144 kit. It could be a bit pricey though. Or consider selling the 125 and picking up a KDX 200. It will be heavier but the abundant low end power and smooth delivery could make up for the weight. Lowering it would help mask the weight also.

megad:
athena came out with a 144 kit?

Last time I looked the athena kit was only 125cc and the dyno was the exact same on bottom end, only change was at high rpm


I have a ktm 200 xc and oooohhhh man is it ever nice, I run a gear higher everywhere it pulls the front end up whenever I want, it really is THE woods bike for small framed guys like me


I'm setting up the 125 for my wife now

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