Home Forums 2-Cycle Racing CR125 Build Questions

This topic contains 4 replies, has 3 voices, and was last updated by  John Lafakis 5 years, 6 months ago.

  • Author
  • #25114

    John Lafakis

    I’m rebuilding a 99 CR125 and had a question regarding the HPP power valve actuator rod.  I noticed that some engines may have this removed.  Do I need to remove this rod for karting? Also, if I remove the rod do I need to plug the hole?  Pics would be appreciated as I’m having trouble finding any online and I’ve read of plugs made for this purpose.

    Also, what’s the best cylinder hone to use on these, and what should the final measurements be on the cylinder?  The piston overheated and left ring material on the cylinder and I’m trying to salvage it with a hone before I succumb to buying a new cylinder.  Rest of the cylinder is fine with no scoring or cracks as far as I can tell.

    Thank you for any help!

  • #25142

    johnny brooks

    Start here:

    Here’s a follow up to above:

    Ask your ‘hone’ question in the ‘shifter kart’ thread…’nikasil’ cylinders require careful attention.

  • #25160

    John Lafakis

    Thanks, I’ve seen those before and they are very helpful, but it only briefly covers the removal of the actuator rod.  I’m assuming this is left out for kart racing since all the built engines I have seen are removed.  since the cylinder is in need of repair as it sits I’ll just hit it with a standard hone and hope for the best.  If it ends up going out of spec I’ll just buy a new cylinder or have it sleeved.

  • #25367

    Greg Wright

    Don’t have the cylinder sleeved. There are a number companies such as Millenium Technologies that do a bang up job of refinishing the bore.

    Greg Wright
    Rapid Racing Inc.
    Vintage B-Stock Pilot
    "When in doubt Gas it, It won't help but it ends the suspense."

  • #25370

    John Lafakis

    I ordered the proper hone for the cylinder, I’ll see if it can be touched up.  If. The hone doesn’t work then I’ll call millenium like you recommended.

    Thank you for the help

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