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  1. #1
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    KX85 engine vs KX100 engine

    What is the main characteristic differences between the KX85 engine and the KX100 engine? Would the 100 have more low end? Does one rev out quicker or further than the other?
    I ask because I just purchased a 2007 KX100 engine to put in my son's 2005 KX85. I am hoping I will not be disappointed with this conversion, but I can always put the 85 top end on this 100 bottom end if I have to. I was just curious what the power characteristics will be like and any pros or cons to this set-up.
    BTW he is not racing, but he is riding some pretty steep and knarly trails.







  2. #2
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    I put a 100 top end on my son's 85 and it's doing well. It pulls my 175+ lbs. around and he rides it in hare scrambles. The 85 would rev higher and have more of a hit to the powerband. The bigger bore of the 100 mellows it out just a tad.



    m y   s i g n a t u r e:


    CRIM
    Green is Good.

  3. #3
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    Boy I hope he isn't too disaapointed, the KX85 already has a pretty weak hit compared to the CR's and YZ's. Does the 100 have anymore low end grunt or is it just like a mellowed out 85?




  4. #4
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    Nothing mellow about it. Just beefier and not quite as pipey.




  5. #5
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    Well that sounds good! Do you think it will make it better for tight woods riding with lots of steep uphill trails?
    BTW thanks so much for your input gwcrim!




  6. #6
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    That's basically what we ride. My boy is a big 9 yr old and he does great on it.




  7. #7
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    That little bike actually scares me more than my 500.




  8. #8
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    I know this sounds like 100 questions.
    Have you done any special mods or did you just bolt on a stock KX100 top end and a stock KX100 pipe or?

    I am getting the engine, electrics, cdi, ignition coil, carb and stock KX100 pipe all from a 2007 KX100. So I guess my set-up will be 100% stock KX100.




  9. #9
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    All I did was buy a 100cc jug, piston, and head. The KIPS valve needed shaved a little to clear the piston, but that was basically it.




  10. #10
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    Thanks again for all the info.




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