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Ul compression release

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  • Ul compression release

    42 ul compression release valve, anyone ever hear of suchlike? My 42 is a bear to kick over,on rebuild I had 84 inch wheels installed, DUH. Motor is incredibly strong my 74 year old leg for some reason has gotten weaker.

  • #2

    Years ago someone was making a decompression valve that screwed into the big sparkplug (1947 down) hole and then a smaller plug with a longer reach was screwed into to it. Very clever and it worked for a friend of mine but I have searched and have not been able to locate any such thing on the internet. Possible a one off thing.



    • #3
      Thanks Jerry, you shook some neurons loose, I seem to recall seeing exactly what your talking about. Now to dig it back up. Thanks


      • #4
        Use some early heads with a primer cup hole in them, find some dirtbike compression releases to adapt.
        Robbie Knight Amca #2736


        • #5

          *Spark Plug insert 14mm to 18mm. ($9.00) -----> *BOLAXIN Company on Amazon. Would have to modify the adapter.

          **Compression Release Kit. ($150.00) ----->

          **Wimmer only makes this for 12mm & 14mm spark plugs~~They also provide the modern spark plugs.

          ***Extended Spark Plug. ($40.00)
          Last edited by JoJo357; 01-10-2024, 04:23 AM.


          • #6
            I believe Spyke still makes the compression release that adapt in spark plug hole location that Jerry is referring to. I haven't checked for awhile either.
            KPI makes various versions of length as does Vulcan. I've machined many Harley Davidson heads and used these before. I'm just guessing that would be fairly easy to locate a position and machine a set for your heads on a UL?
            Last edited by dukekleman; 01-10-2024, 04:23 AM.


            • #7
              Dear Rich, consider thicker spacer plates under the cylinders to reduce compression.


              • #8
                Thanks to all,now to decide which avenue to take??
                I like Steve's idea of extra thick base gasket, but then again a real relief valve would be easier (in my mind) Chico and toco(me 2 neurons) are goin at it.
                Thanks guys