Valve seats. Opinions wanted.

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • Machine
    • Feb 2026

    #1

    Valve seats. Opinions wanted.

    So on a close inspection of my valve seats, there is no way they will lap in and take out all the pitting in the sealing surface, especially on the exhaust seat. I priced it out, and it will cost $300 for a regrind for the valves and seats to match at a local shop. A reasonable price IMO.

    My other option is borrowing a seat cutting tool. I have a relative who is an engine builder and has a metric set that is pretty complete. I realize that the job that I would do with these will not be as good as a fully equipped machine shop, but I have nothing but patience and time.

    Is it really worth the money? ($300 can buy a good deal of shiny things) Has anyone done this job before? Let me know what you think. Thanks in advance to all.

  • Nessism
    Forum LongTimer
    GSResource Superstar
    Past Site Supporter
    Super Site Supporter
    • Mar 2006
    • 35790
    • Torrance, CA

    #2
    APE charges $189 for an 8V valve job. No guide work, just resurface the seats and valves.

    If you can get your hand on some hand cutters I'd go that way. Pay someone to do your valves. I use Neway cutters and they do a fine job.
    Ed

    To measure is to know.

    Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

    Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

    Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

    KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

    Comment

    • Big T
      Forum LongTimer
      Past Site Supporter
      Super Site Supporter
      • Mar 2005
      • 12392
      • West Slope, OR

      #3
      If you plan to do this yourself, don't overcut!

      The actual mating surface is typically about 2 mm
      1978 GS 1000 (since new)
      1979 GS 1000 (The Fridge, superbike replica project)
      1978 GS 1000 (parts)
      1981 GS 850 (anyone want a project?)
      1981 GPZ 550 (backroad screamer)
      1970 450 Mk IIID (THUMP!)
      2007 DRz 400S
      1999 ATK 490ES
      1994 DR 350SES

      Comment

      • Nessism
        Forum LongTimer
        GSResource Superstar
        Past Site Supporter
        Super Site Supporter
        • Mar 2006
        • 35790
        • Torrance, CA

        #4
        Originally posted by Big T
        If you plan to do this yourself, don't overcut!

        The actual mating surface is typically about 2 mm
        Spec is 1mm. Clean up the 45, then use a 15 and 75 to narrow the seat down to spec.
        Ed

        To measure is to know.

        Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

        Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

        Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

        KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

        Comment

        • Machine

          #5
          Ive got the teardown manual. They detail the angles and permissible sealing surface area. 0.047 inches max if memory serves...

          Thanks again for the input. Ill post a picture of the finished product for everyone to inspect

          Comment

          Working...