Home Forums Shifter Karts CR125 Bottom end rebuild

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    • #83156
      Jerad Lang

      <p style=”text-align: left;”>New to Shifter Karts.  I recently broke off a small piece of my piston, the ring was welded to one side of the piston.  The head had some gouges in it.  I took it apart, lightly honed the jug. Put in a new to end.  Lightly broke it in on the stand.</p>
      half a lap in, it dies.  Pull off the head.  Has a large goldish fragment in it. One side of piston is welded to the ring. A deep gouge in the side of the piston (I’m guessing from the fragment that ended up in the head).  I took off the jug. See a large goldish piece of metal wedged in the crank assembly.

      I have never done a bottom end rebuild. Any words of wisdom as to if I should attempt this, and if so, what tools I should buy specific to this task? I’m on a definate budget and would like to do this myself, although I also want a running engine when all said and done

      thank you

    • #83209
      William Martin

      This all depends on how experienced you are in general with small engines. If you are used to working on high performance stuff, the only thing I would suggest is that you take the crank/rod assembly to a shop that can do the rebuild, or just buy that assembly new from a Honda bike shop. It’s kind of tricky stuff, aligning the two crank halves and pressing together…buy some experience, you won’t regret it. The rest you should be able to handle. You will need to do a thorough cleaning/flushing of the crankcase to get the various other bits of metal out that may be hiding in there some place. If you don’t have the Honda cr125 manual, get one and read it before you dive into this! Probably you will want to replace crank main bearings while it is apart, much cheaper than after one lets go…


    • #83273
      Brad Clem

      If you have decent experience working on stuff, you should be able to do this.  Rocky Mountain ATV has a 3 part YouTube video that I used the first time I did it.  You will need a few specialty tools.

      Tip: Do not let the transmission fall out or lose order of its parts.

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