KX100 internals question:

[jackdrinker]

I have a couple q's about the KX100...
Is the jug a bored 85 or a sleeved down 125?
Which rod does it have?
Is it possible to run a 125 rod and jug combo?

My friends dad wants to get into dirt and he's pretty short... This bike fits him well...

 

[NM_KDX200]

I'm 5' 5" and considered a KX100, but found an 01/03 KX125 in great shape and well-modified. It fits me very well and now my KDX200 feels like a tank. He should defintely try an 01-03 KX125 before making a decision on the 100.

 

[slickpuss]

I believe it is a 80/85 with a bigger cylinder. I dont think you can really compare it to a 125. Its more like a 80 that has a tad bit more bottom end and smoother.

 

[gwcrim]

The 100 and 85 jugs are interchangeable, just need the correct piston, head, and KIPS valve.

 

[motometal]

think of it as a short stroke 125. The bores are almost the same.

 

[bikepilot]

the 125 parts will not fit, the KX100 is the same as the KX85, only with a larger bore. The cylinder casting is the same. The pre-power valve models could be bored to 107 reliably. The newer ones have thinner exhaust bridges and can't be bored much over 100cc. You can stroke either to 48mm which yeilds some power improvement (and makes a 100cc into ~105cc iirc). Even stock the bikes are quite fast though and when you take into account their light weight (150lbs) they are really fast.

My sister races an older KX with a 107cc big bore kit. My wife rides a newer KX with the 48mm stroker kit. they both run quite well but a direct comparison doesn't make sense as my sister's bike has woods-specific porting and my wife's has the standard MX porting. The end result is my sister's bike has more low end while my wife's has more mid and top. Both are quite fast though, my sister hole-shot the 200-C class several times on her bike:)