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Engine Oil Seals

Discussion in 'The Garage' started by 5twins, Jun 21, 2018.

  1. 5twins

    5twins XS650 Guru Top Contributor

    There's been some oil seal talk recently, particularly about the cam shaft seals, and I realized I really didn't know too much about oil seals in general. So I decided to educate myself, which proved quite easy. One simple Google search turned up all the relevant info. Oil seals have a code number, usually stamped right on them, that gives the seal type and size. The 1st entry in the code is the seal type and consists of 1 to 3 letters. The numbers following are the size, in our case in MM (I.D. x O.D. x thickness). Determining the 650 seal types and sizes proved pretty easy because they are listed in the earlier factory parts manuals, so I made up a chart .....


    Now let's talk a little about seal types. It was pretty easy to find well illustrated info on that. There are as many as 5 different types used on the 650 engine. Some types changed when seals were updated so you may not find all 5 on your particular machine. Most of the seals are the "SD" type, with a sprinkling of "SO" and "SDD" types thrown in. Here's cross sectional drawings of the various types .....


    And here's a little tidbit of info about the "SD" type I found interesting, highlighted below .....


    Looks like I'll be packing some grease into them before install from now on. Maybe it will help them seal better, and I certainly don't see it hurting anything.
    Last edited: Jul 6, 2018
    peanut, 59Tebo, GLJ and 8 others like this.
  2. 5twins

    5twins XS650 Guru Top Contributor

    Seal sources have also been mentioned recently. MikesXS was mentioned as a good place for quality seals. Granted, they do have good ones, the same ARS brand as the originals, but their prices aren't very good at all, many times twice what you can get them from Yamaha for. Here's a comparison chart. Yamaha prices are the discounted ones from Partzilla. The only seal we're beholding to Mike's for is the starter motor shaft seal because it is N.L.A. from Yamaha. Thankfully, that seal doesn't go bad often .....


    I thought I'd also talk about the cam seals a little. 2m posted a listing from the XS1-XS1B parts manual showing the 2 types. The early seal was 5mm thick, the replacement in mid '71 was 6mm thick. This "upgraded" seal was then used until the end of production. But now it seems Yamaha has reverted back to using the old 5mm thick seal again, and under that same old original part number.


    2M also postulated that the "S" type was probably a single lip, and the "SD" type a double lip seal. That's somewhat correct. The "SD" type does have an extra lip but it's a dust or wiper lip, not another actual seal lip.
    59Tebo, GLJ, Marlin72xs and 6 others like this.
  3. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Excellent write up, 5twins!
    Another candidate for the Tech section.

    There's a couple other features of note. The outer retention ring, or barb, and the swirl pattern in the lip of the clutch pushrod seal. If I may, some links:

    Alternate seal options by member inxs:


    Discussion about the seal retention ring, or barb:


    gggGary's Great seal thread:

    peanut, GLJ, DigitalXS and 2 others like this.
  4. 5twins

    5twins XS650 Guru Top Contributor

    Yes, I noticed the swirl pattern on some of the seals. The crank seal has it as well. These "swirled" seals appear to have a direction arrow on them. I assume that indicates the direction of shaft rotation they are to be used on .....



    But the direction arrows point opposite to one another. Does the tranny shaft that the pushrod goes through rotate opposite to the crank? I know the crank rotates counterclockwise so it's seal direction arrow would seem to be a match for it.
  5. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Great closeups of those seals.


    Edit: What I don't like about the "swirl" on the clutch pushrod seal, is that the pushrod not only spins, but goes in/out, and in a severe "grunge" environment. Any grit that gets past the outer lip will be "drilled" inward, into the tranny oil system, and the pushrod bushing...
    Last edited: Jun 21, 2018
    Marlin72xs and robinc like this.
  6. 5twins

    5twins XS650 Guru Top Contributor

    Yes, one of the few things MikesXS is good for (pictures), lol.
    robinc likes this.
  7. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    I'd thought about augmenting the pushrod seal with some type of "dome seal".


    The pushrod moves in/out no more than about 2mm. The dome center would be a tight grip on the pushrod, and simply flex with pushrod movement. Now I gotta find one...
    robinc likes this.
  8. xjwmx

    xjwmx It's just the unknown. Top Contributor

    The pushrod isn't driven though and if there's proper freeplay there's probably not enough incidental friction to make it rotate at all. Probably a good reason to favor the two piece rod over the one piece (more bearings less friction).
  9. DogBunny

    DogBunny Motorcychologist Top Contributor

    Some Yamaha XS650 seal trivia:
    The service bulletin where they changed the output shaft oil seal type, allowing replacement without splitting the cases. The push rod seal is also this type, which is why we can also replace it without splitting the cases. There are other seals like this on our engines...

    OOOPS! Page 191 of my Clymer manual, they mislabeled the seal drawing...

    But the Haynes manual got it right, page 146.
    gggGary and TwoManyXS1Bs like this.
  10. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    There is positive oil pressure behind the pushrod seal also. Anyone that's started an XS without the LH cover on knows.
    I did put a link to this thread in the seal, washer, bolt, thread.
    TwoManyXS1Bs, robinc and xjwmx like this.
  11. Superjet

    Superjet XS650 Guru Top Contributor

    Cool write up! Thanks.
  12. Ozboy

    Ozboy XS650 Addict

    Great write up 5t.
    I had a small weep on the right cam seal and tried fixing it many times by cleaning the sharft and replacing the seal. In the end I spedi sleeved the shaft.
    It was not easy trying to break the rear installation ring but pre cutting it to the groove made it easier.
    Used a small amount of loctite to retain it plus got a good SKF dual lip seal not the Mikes rubbish i was using.
    Put 300kms on it now it it has finally stopped!
    gggGary likes this.
  13. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    Would love to see details on a a speedi sleeve install.
  14. 5twins

    5twins XS650 Guru Top Contributor

    I don't think the 7mm thick "improved" cam seal from Mike's is necessarily a bad seal, it's just wrong for this application. It's too thick. It can't be seated deep enough into the points/advance housing for the seal lip to get good purchase on the end of the cam shaft. There are quite a few reports of it not working at all or failing shortly after install. Yamaha originally used a 5mm thick seal here, then switched to a 6mm thick one, and now has gone back to using the 5mm thick one again. So, it appears thinner is better in this application. The seal lip is able to sit deeper onto the end of the camshaft and do it's job better.
  15. Ozboy

    Ozboy XS650 Addict

    Yeah I went with the 40x25x5mm seal on this as the Mikes ones were 6mm and I did need the extra 1mm.
    I didnt do any photos of the install but they are really simple to install as they come with the installation outer sleeve to hammer the inner speedi sleeve on.
    They key was to pre cut the rear raised lip for installing the speedi sleeve with a Dremel to the grooved line on the main sealing surface. i did it in 3 places. Then when installed carefully tear iit away with pointy plies without damaging the sealing surface to leave a nice new Stailess Steal resleeved shaft. You can leave the rear raise installation sleeve
    Cost was $21AUD.
    Check out SKF site with small video.
    TwoManyXS1Bs likes this.
  16. Skip

    Skip XS 650 Screwturner

    Great information Guys...Thank you
    robinc likes this.
  17. tzimmerm

    tzimmerm XS650 Junkie XS650.com Supporter Top Contributor

    Iowa City
    I’m feeling better about my new 5 mm cam seals now. Can’t wait to get them and my new pamco on and be points/oil free. Good to know about the grease, too! What kind of grease should I use here?
    Last edited: Jul 10, 2018
  18. Ozboy

    Ozboy XS650 Addict

    Nothing more satisfying than buttoning down oil leaks for good on these old girls.
    Grease for the seal was just normal bearing grease around the lip.
  19. Paul Sutton

    Paul Sutton Sprained Ankle Top Contributor

    In the UK 3rd Party pushrod seals come in a variety of thicknesses - 6mm, 7mm and 8mm.
  20. Oops, didn't mean to quote the whole thing. Great info. My recent rebuild has some seeping on both cam seals. Both are from Mikes. I carefully installed the cam so there was equal space on each side, and the seals are right at the edge on both sides. I'm hoping that 1mm less should do the trick. I'm also wondering if Mikes O-rings are too thick. That would add to pushing the seal out also.
    Again, great info, as usual.
    Gator xs2 likes this.

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