Home Forums 2-Cycle Racing Power valves removed?

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    • #47498
      Joeb1983
      Participant

      Recently picked up a kart powered by a YZ125. I went to replace the power valve cover gasket and noticed the entire orifice filled with hight temp RTV…

      Am I correct in assuming they are removed?

      From what Google tells me, kart guys do not care about low RPM power seeing how they are usually high in RPM’s most of the time. So they plug them.

      I’m not racing it competitively, never owned one before, and just bought the thing for.some fun.

      Should I be concerned, look into installing them again?..

    • #47520
      Walt Gifford
      Participant

      I’ve seen them plugged with carved aluminum blocks. RTV sounds like red neck engineering. You can run for fun without a power valve. If it’s not fast at least it’ll be loud.

      Gif

      FAA certified jet engine and aircraft technician,
      Nicholson Speedway class champion 2001,
      Yamaha KT100 Service Center,
      41 years karting experience

    • #47539
      Joeb1983
      Participant

      Well, I am stationed in Oklahoma and the individual I purchased the kart from may or may not fit that description to the “T”… Haha!

      I see plug kits all day long for the CR125, but nothing for the YZ125 (Probably why all the RTV) any out there that you (or anyone else) know of?..

      I’d feel more comfortable with an actual R&D’d kit installed or seeing about the process of re-installing the power valve setup.

      I know its a 2-stroke kart and not a dirt bike, but I was wondering why it had little to no low-mid power and the “light switch” effect was so drastic. (again, first shifter kart and learning)

       

       

       

    • #47559
      Walt Gifford
      Participant

      I would sell that engine and get you a Briggs LO206.

      Gif

      FAA certified jet engine and aircraft technician,
      Nicholson Speedway class champion 2001,
      Yamaha KT100 Service Center,
      41 years karting experience

    • #47626
      Joeb1983
      Participant

      I think I’ll hold onto the yz, but appreciate the suggestion. Thing is a blast banging through the gears! Plus I just threw a Hinson clutch kit in.

      Just pulled all the RTV out and found the power valves were JB welded in place… Slowly chiseled them out. Ill clean it up even more with the dremel.

      The push rod is still there and connected, so I ordered a excellent used power valve assembly/set with all the hardware.

      Hopefully I’ll get it by this weekend and throw it in while rebuilding the carb. (Keihin 72R/39mm)

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