How to tell what rings you have........

Discussion in 'Airheads' started by chasbmw, Oct 24, 2014.

  1. chasbmw

    chasbmw Long timer

    Joined:
    Feb 19, 2006
    Oddometer:
    3,653
    Location:
    Bath Uk
    Is there any way to tell apart rings suitable for Nikilisil cylinders from rings suitable for linered cylinders?
    #1
  2. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

    Joined:
    Nov 16, 2006
    Oddometer:
    6,676
    Location:
    Bowling Green, Ky
    NOT true, different rings!!!!
    #2
  3. Big Bamboo

    Big Bamboo Aircooled & Sunbaked Supporter

    Joined:
    Sep 29, 2010
    Oddometer:
    16,497
    Location:
    Big Island of Hawaii
    Nykasil: [​IMG] ......................and NON-Nykasil: [​IMG]
    #3
  4. bmwrench

    bmwrench Long timer

    Joined:
    Nov 10, 2006
    Oddometer:
    7,830
    As Big Bamboo's picture shows, they are different. The top ring for an iron-bore cylinder is chrome-plated steel. Chrome will rapidly destroy Nikasil, which distributes itself on the piston, destroying it, too. The second ring is identical, and I suspect the oil ring could be used interchangeably.
    #4
  5. chasbmw

    chasbmw Long timer

    Joined:
    Feb 19, 2006
    Oddometer:
    3,653
    Location:
    Bath Uk
    Many thanks for the help guys, it looks as if I have the correct rings for my cylinders. (Top ring chromed for non nikilsil)
    #5
  6. fxray

    fxray Long timer

    Joined:
    Feb 22, 2014
    Oddometer:
    1,469
    Location:
    Illinois, USA
    I got some Goetze Rings from Motobins for my '74 R90/6, so non-Nikasil cylinders. The box is marked for STD R90/6, R90 S. Part number is BMW Motorrad 08-700800-00, and Motobins part number is 50410, which I believe is correct.

    Looking at the pictures posted above in this thread (by Big Bamboo), the rings pictured for the Nikasil cylinders have the coil spring backer on the oil control ring. The set for the non-Nikasil cylinders doesn't have the coil spring.

    Is this for sure always true? My oil control rings have the coil spring, making me wonder WTF?

    Ray
    #6
  7. bmwrench

    bmwrench Long timer

    Joined:
    Nov 10, 2006
    Oddometer:
    7,830
    Normally only ring sets for Nikasil have a spring backed oil ring. I've been tempted to try one of those oil rings in an iron-bore motor for years. If it fits for piston properly, I'd certainly try it.
    #7
  8. fxray

    fxray Long timer

    Joined:
    Feb 22, 2014
    Oddometer:
    1,469
    Location:
    Illinois, USA
    O.K., I guess I will. I was a bit confused because the picture for standard replacement rings from Max and from Bob's shows no spring backer. I bought from Motobins because they were a lot cheaper. Thanks for the reply!

    Do you know why that coil backer is generally only used with Nikasil? Does it make for too much ring pressure for iron cylinders?

    Another thing about these Goetze rings is that the second ring is napier cut. I see where you have said you like that with Hastings rings.

    #8
  9. Disston

    Disston ShadeTreeExpert

    Joined:
    Aug 31, 2009
    Oddometer:
    16,294
    Location:
    Silver Spring, Md
    The oil rings with a spring are just the latest design so the new stuff was applied to Nikasil first and it will be seen on the iron cylinders eventually.
    #9
  10. fxray

    fxray Long timer

    Joined:
    Feb 22, 2014
    Oddometer:
    1,469
    Location:
    Illinois, USA
    Thanks, disston. So my 41 year old airhead will be on the cutting edge of technology if it ever sees the road again? :D
    #10
  11. Beemerguru

    Beemerguru Beemerguru...G/S guy

    Joined:
    Nov 7, 2006
    Oddometer:
    1,867
    Location:
    Redwood City, CA
    Part number!!! All beemers from '81 on were Nikasil.

    Use a magnet on the inside of the cylinder..if it sticks,,you have iron bore, doesn't, then Nikasil. Each has a different part number...install the wrong ones, and either it will not seal or damage the cylinder surface. No oversize for Nikasils so if iron bore, measure to see if it was bored 1 over in the past.
    #11
  12. fxray

    fxray Long timer

    Joined:
    Feb 22, 2014
    Oddometer:
    1,469
    Location:
    Illinois, USA
    Well, O.K., that would tell if you have Nikasil cylinders (I know I don't have), but the question was how to identify if a ring set is right for iron or Nikasil bores. You are probably right -- just go by the part number and trust the supplier to send the right thing. Except -- for those with Nikasil, it sounds like a really bad mistake to try to run chrome plated rings if the dealer sent them by mistake.
    #12
  13. Beemerboff

    Beemerboff Long timer

    Joined:
    May 23, 2005
    Oddometer:
    3,401
    Location:
    Adelaide, South Australia
    Just wondering how Nikasil type rings go in a cast iron barrel , and how they go in a Galnickel barrel , which was the treatment on quite a few bikes?

    FWIW I ordered a set of both cast and electroplate rings and was set two identical sets of non chrome plated rings.

    Will they work and last as long as the plated ones and does my bore prep have to be different on the CI barrels. ?
    Actually I havent seen much on bore prep on cast iron barrels so probably a silly question, not like the days when the instructions came with the rings.
    #13
  14. bmwrench

    bmwrench Long timer

    Joined:
    Nov 10, 2006
    Oddometer:
    7,830
    Chromed steel top rings were developed to tolerate the high temperatures and pressures they encounter. I've used cast iron top rings in quite a few iron bore motors without any problems, and they obviously work well on Nikasil. If you want just a chrome ring, I can probably help.
    #14