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  • Cartridge oil filter bypass???

    One spec on the XS bikes still eludes me and hope someone here knows........

    I'm down to just a few K&N cartridge filters in my XS parts stash and have a spin on adapter standing by. I know it exists somewhere but I've never been able to find the spec for the filter bypass pressure on the OEM setup.

    Existing standard spin on oil filters with 20x1.25 threads have a range of filter bypass specs 4-27 psi

    Want to make sure I'm in the ball park. Too low would not filter well and too high would starve top end of delivery pressure. (Guessing 8-10 psi is proper)

    ---Bax
    80 SG

  • #2
    Took me a while to find it in the Service Manual, the Relief valve opening pressure is a whopping 70 PSI ! Cruising oil pressure is 42 psi.
    Now, for that spin on adapter, I made those. IIRC the thread specs are 20 mm x 1.5 pitch, not 1.25. You should have the mounting threaded pipe section that you can use a pitch gauge on to double check.
    The oil filter that fits it is the BIKE Fram PH-6017A, here's their info link: https://www.fram.com/parts-search/PH6017A/ and it also states 20 x 1.5mm thread/pitch! Surprisingly that filter's bypass is 9-15 psi?
    I am surprised that it's that LOW for a bike engine, especially when this filter has been used on other large CC sized bike engines?
    T. C. Gresham
    81SH "Godzilla" . . .1179cc super-rat.
    79SF "The Teacher" . . .basket case!
    History shows again and again,
    How nature points out the folly of men!

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    • #3
      Thanks TC. I saw my pitch mistake after posting.......... That was a popular filter for 5W-30 spec'd engines, prob why the relief was so low......

      Bax
      80 SG

      Comment


      • #4
        I just checked on that Fram website, the filter for the Vmax is the 6018, and it's bypass pressure is only 12 !? Just checked the Vmax forum, they state usual oil pressures are around 40 at 4k rpm also. So that makes me feel better about the Fram filter, that if the Vmax can use a filter with 12 PSI bypass pressure, that it probably isn't seeing that kind of pressure when the filter is clean and the oil is flowing thru it easily. IT probably only sees the increased PSI when the filter is dirty and much more restrictive to flow and that is when it would bypass it to keep the engine lubed albeit with dirtier oil, but oil none the less. I don't think the actual running oil pressure of 40 is going to cause the bypass valves to open under normal operation. And "we" usually change the filter every 3 or so thousand miles, probably no where near the sludge point of oil consistency and clogging of the filter. The oil gets contaminated due to the loose clearance specs, the ring blow by affect, etc., so I believe the spin on filter is still safe to use. This quick contamination of the oil is why "we" don't usually recommend using PURE SYNTH because it's so $$ and it gets so dirty so fast you don't get to utilize the long life, slow breakdown of Synth oil that you can benefit with modern very close toleranced engines that keep the oil much cleaner for thousands of miles!?
        T. C. Gresham
        81SH "Godzilla" . . .1179cc super-rat.
        79SF "The Teacher" . . .basket case!
        History shows again and again,
        How nature points out the folly of men!

        Comment


        • #5
          If you ever get around to making more of those adapters TC, I could use a couple.
          Greg

          Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

          ― Albert Einstein

          80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

          The list changes.

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