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Nikaseal worn around exhaust port. YZ250 and YZ85

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  • Nikaseal worn around exhaust port. YZ250 and YZ85

    I just wanted to pick the brains of the 2 banger gurus on here.
    I have the top ends apart on my YZ250X (166hrs) and my sons YZ85 (178hrs). Both show the same signs of wear.
    Iím wondering if I should be getting more out of my cylinders than I am.
    Iím very anal about clean air filters and run Castrol TTS Racing at 40:1.

    What is causing the Nikasil to prematurely wear like this!

    Yz250x bore.


    YZ85 bore


    YZ85 head.
    Present:2016 YZ250X
    1990 YZ490
    2014 YZ 125
    Past:2016 KTM 300EXC
    2010 YZ 250
    2007 YZ 125
    2011 YZ 450F SE
    2009 YZ 450F SE
    2001 YZ 426F
    1998 RMX 250
    1990 DT 200
    1987 YZ 80
    1984 DS 80
    1980 PW 50
    http://www.youtube.com/user/v8utes/videos

  • #2
    I have never been a fan of TTS. A mate children's bikes had repeated failures when their father switched to TTS due to sponsorship obligations (free oil). Went back to Motorex all good. I personally run ELF
    NO WUCKIN FURRIES.

    Comment


    • #3
      Originally posted by oldboy View Post
      I have never been a fan of TTS. A mate children's bikes had repeated failures when their father switched to TTS due to sponsorship obligations (free oil). Went back to Motorex all good. I personally run ELF


      I like how the castrol burns so clean (as you can see from how clean the head on the 85 is).
      I have done tests on motorex for 40hrs and castrol for 40hrs. The castrol piston was so much cleaner.
      But maybe itís luberication properties are not good enough.
      Present:2016 YZ250X
      1990 YZ490
      2014 YZ 125
      Past:2016 KTM 300EXC
      2010 YZ 250
      2007 YZ 125
      2011 YZ 450F SE
      2009 YZ 450F SE
      2001 YZ 426F
      1998 RMX 250
      1990 DT 200
      1987 YZ 80
      1984 DS 80
      1980 PW 50
      http://www.youtube.com/user/v8utes/videos

      Comment


      • #4
        I run $5/litre 2T oil and my cylinders don't look like that!

        Are you sure it is the nikasil wearing? Does the mark polish off? ie is it definitely worn or is there melted aluminium coating the cylinder there? What is the mark at the top of the 85 bore?

        Aftermarket pistons too tight?

        What do the pistons look like?

        It all looks too clean to me....jetting too lean? Even then I would expect to see some carbon cooked on.

        I have no idea what the issue is but I think it is more than brand of oil.

        Comment


        • #5
          Classic lube-film failure, exacerbated by hot burn.

          *Change to Motul 800T,
          *Don't go any hotter than BR9EG in either bike,
          *Don't use EIX plugs,
          *Jet them a touch fatter on the MJ
          *Change the PJ/needle-straight balance (PJ richer/NS leaner)
          *Read the "Spooge ain't bad" thread.

          http://www.dirtbikeworld.net/forum/s...ghlight=Spooge

          Simple lubricant failure Gibbit, identical in both bikes...common demoninator? Oil. Not hard...

          BTW, what premix ratio were you running?
          "Mindfulness has no interest in knowing the answers, it exists solely in understanding the questions"

          Comment


          • #6
            I used to get the same wear on my YZ250s at around 200 hours, however not to that extent. Using Rock Oil K2, mostly trail riding at low revs.

            Comment


            • #7
              Originally posted by JJW View Post
              I run $5/litre 2T oil and my cylinders don't look like that!

              Are you sure it is the nikasil wearing? Does the mark polish off? ie is it definitely worn or is there melted aluminium coating the cylinder there? What is the mark at the top of the 85 bore? Definitely worn. The mark at the top of the bore is the ring mark

              Aftermarket pistons too tight? Only use Oem pistons matched to the bore size. A,b or C ect.

              What do the pistons look like? Clean but have been a little hot

              It all looks too clean to me....jetting too lean? Even then I would expect to see some carbon cooked on.

              I have no idea what the issue is but I think it is more than brand of oil.
              See above in Red
              Present:2016 YZ250X
              1990 YZ490
              2014 YZ 125
              Past:2016 KTM 300EXC
              2010 YZ 250
              2007 YZ 125
              2011 YZ 450F SE
              2009 YZ 450F SE
              2001 YZ 426F
              1998 RMX 250
              1990 DT 200
              1987 YZ 80
              1984 DS 80
              1980 PW 50
              http://www.youtube.com/user/v8utes/videos

              Comment


              • #8
                @JJW. What oil do you run? pm if you prefer. Cheers

                Comment


                • #9
                  Originally posted by Nutty View Post
                  Lube film failure, exacerbated by hot burn.

                  *Change to Motul 800T,
                  *Don't go any hotter than BR9EG in either bike,
                  *Don't use EIX plugs,
                  *Jet them a touch fatter on the MJ
                  *Change the PJ/needle-straight balance (PJ richer/NS leaner)
                  *Read the "Spooge ain't bad" thread.

                  http://www.dirtbikeworld.net/forum/s...ghlight=Spooge

                  Simple lubricant failure Gibbit, identical in both bikes...common demoninator? Oil. Not hard...

                  BTW, what premix ratio were you running?
                  Cheers Nutty. Your always on the money. I'll give 800T a go. I already don't use EIX plugs. I usually just go with the recommended plug temp.
                  I run 40:1 in all my 2st (even the TC50 and TC65) but change to 32:1 for Finke and any fast enduro's.
                  Present:2016 YZ250X
                  1990 YZ490
                  2014 YZ 125
                  Past:2016 KTM 300EXC
                  2010 YZ 250
                  2007 YZ 125
                  2011 YZ 450F SE
                  2009 YZ 450F SE
                  2001 YZ 426F
                  1998 RMX 250
                  1990 DT 200
                  1987 YZ 80
                  1984 DS 80
                  1980 PW 50
                  http://www.youtube.com/user/v8utes/videos

                  Comment


                  • #10
                    Nikaseal worn around exhaust port. YZ250 and YZ85

                    Originally posted by Chewy View Post
                    I used to get the same wear on my YZ250s at around 200 hours, however not to that extent. Using Rock Oil K2, mostly trail riding at low revs.


                    The 250 piston had done 57hrs of finke prerunning, plus the race, a Transmoto 6hr and a few other pretty fast WOT enduros. I change from a 178mj to a 190mj for any fast WOT stuff.



                    The 85 piston had done about 90hrs of reasonably easy trailrides and MX. My son is no Pro but keeps it in the powerband pretty well.



                    Present:2016 YZ250X
                    1990 YZ490
                    2014 YZ 125
                    Past:2016 KTM 300EXC
                    2010 YZ 250
                    2007 YZ 125
                    2011 YZ 450F SE
                    2009 YZ 450F SE
                    2001 YZ 426F
                    1998 RMX 250
                    1990 DT 200
                    1987 YZ 80
                    1984 DS 80
                    1980 PW 50
                    http://www.youtube.com/user/v8utes/videos

                    Comment


                    • #11
                      Just out of interest Gibbit, have you measured the wear on the pistons?

                      90 hrs is a lot for the 85:speechles

                      Comment


                      • #12
                        Originally posted by 380EXCQLD View Post
                        Just out of interest Gibbit, have you measured the wear on the pistons?



                        90 hrs is a lot for the 85:speechles


                        I donít own a micrometer but checking the piston to bore gap the dodgy way with a feeler gauge, the 85 had a gap of .127mm and the 250 has .178mm.
                        Ring gap for 85cc is .4mm
                        and 1.2mm for the 250cc
                        Present:2016 YZ250X
                        1990 YZ490
                        2014 YZ 125
                        Past:2016 KTM 300EXC
                        2010 YZ 250
                        2007 YZ 125
                        2011 YZ 450F SE
                        2009 YZ 450F SE
                        2001 YZ 426F
                        1998 RMX 250
                        1990 DT 200
                        1987 YZ 80
                        1984 DS 80
                        1980 PW 50
                        http://www.youtube.com/user/v8utes/videos

                        Comment


                        • #13
                          Originally posted by Weird Rooster View Post
                          @JJW. What oil do you run? pm if you prefer. Cheers
                          It's no secret....I run Gulf Western Air Cooled at 40:1 and jetted a bit fat - NOT for economy!

                          Comment


                          • #14
                            I know itís an old thread, but did the cylinder need replating with that amount of wear, or did you just put in a new piston & rings?

                            My KTM300 has similar wear, but only a quarter the size of the one pictured.


                            Sent from my iPad using Tapatalk

                            Comment


                            • #15
                              Andy .....see my reply on your other post.

                              To fill in the dots.......any damage to the nikaseal or even scoring means
                              1/ the surface will 'flake' around the exhaust port where your cyl is damaged.
                              the flaking will immed score the cyl and piston which means your straight back where you started.
                              false economy to rebuild the top end with that cyl damage.

                              2/ a scored cyl also like you have will not allow the rings to fully seal on the compression stroke.
                              which is why you currently have low comp readings.

                              only true path is to rebore to remove the 'chip' / flaking.
                              That depth, re new bore diameter has to be assessed to ensure first that a piston sizing is
                              available to fit the 'new' finished cyl diameter once re nikaseal'ed.

                              welcome KTM 315 2T
                              GL

                              Comment

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