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Mailman’s XS2 a full on restoration

Discussion in 'The Garage' started by Mailman, Mar 1, 2018.

  1. Mailman

    Mailman Hardly a Guru Top Contributor

    The valve cover is unique to the ‘72 and ‘73 models. A cable goes from a lever on the right handlebar , just below the brake lever, to the compression release that’s built into the valve cover. When you pull the decompression lever it also activates the starter. The decompression mechanism works by pressing down on the end of the left side exhaust valve.
    1972 was the first year for the electric starter and the motor was not very powerful.
    Later models had a more powerful starter, therefore eliminating the need for a compression release.
     
    Hightower-Ash98, gggGary and Jim like this.
  2. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Re. The cam seals.
    If the goal is to get the cam seals to seat deeper on the cam, simply tap them in deeper after install. I would reckon this should be a preplanned process. Fit the seal only on the camshaft, see and measure the exposed residual camshaft surface. Also see if too much seating depth of the seal will cause the seal's OD will contact the bearing cages.

    When hot, the head will swell more than the cam, up to several thou, allowing the cam to shuttle side-to-side a bit more, possibly allowing a seal lip to lose contact. In anticipation, I'd want near zero side-side clearances during cold assembly.
     
    YamadudeXS650C, Jim and Mailman like this.
  3. Oddjob

    Oddjob adsgads

    Thx for the quick reply... rephrasing my question and adding some context... would the compression assembly work with later year heads? I've got a 73 that looks to have had the head replaced with a later year head assembly, and is currently missing the compression release valve cover... If I were to somehow come across one, would it work with the later head?
     
    Jim likes this.
  4. Mailman

    Mailman Hardly a Guru Top Contributor

    I’m sorry, I am unable to answer, I don’t know if it would fit. There are folks here with a deeper knowledge of what parts will fit other years.
     
    Oddjob and Jim like this.
  5. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    It should, but you'll need the rocker to have the protruding nub that contacts the release cam...
     
    gggGary, Oddjob and Jim like this.
  6. Rasputin

    Rasputin XS650 Addict

    Hello all. I have only just noticed, Mailman’s sympathetic restoration,has changed to, Mailman’s XS2 a full on restoration. Enjoyed the story so far, looking forward to the final page.
    Great story, glad you are settled in to your new garage.
     
  7. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    All four rocker arms had the extended fin for years after the compression release disappeared.
     
    Jim, Oddjob, Mailman and 1 other person like this.
  8. robinc

    robinc Member of the 'yellow meter gang' Top Contributor

    Haven't had the time, heart or energy to get back to this yet Jim. Any spare time was spent riding and then cleaning oil. :(

    It does have to be addressed as it has gotten worse, now with the second set of OEM seals which makes me wonder if in fact the caps and bearings aren't fully seated. :shrug: Possible that both sets of seals were from a bad batch I guess.

    I got some of the 24-40-7 seals that you suggested, have more OEM seals, and have been pondering how to proceed. You had verified through pics that my bearings were fully seated (http://www.xs650.com/threads/on-the-road-again-at-40-the-bike-that-is.49360/page-61#post-556410) but I was wondering if I should back off the rocker box fasteners when I install new ones (boy, which ones?) to make sure the caps will fully seat and give it a go without gaskets.

    Apologies for the hijack Bob.
     
    Jim and gggGary like this.
  9. Mailman

    Mailman Hardly a Guru Top Contributor

    Thanks Rasputin! I just changed the title of my thread last night. Haha! The sympathetic restoration was my original intent. But that kinda got away from me, so I changed the title to reflect that! :laugh2:
     
    Jim and robinc like this.
  10. Mailman

    Mailman Hardly a Guru Top Contributor

    No apologies necessary, I was seeking just this kind of input. I do not understand how such a simple little seal causes so much problems. I really am trying to get a handle on it.

    And 2M, that is a good suggestion. As of now I already have the new seals cemented in place and the rocker cover all sealed up. But I like your idea.
     
    TwoManyXS1Bs, Jim and robinc like this.
  11. GLJ

    GLJ Never go faster than your guardian angle can fly. Top Contributor

    Mailman
    Just a note on the compression release. After you get your bike running you might try an experiment. That is unhook the cable to the decompression assemble. You may find the bike starts better when using the electric start. I know I did. It may have just been my bike but it started a lot better on 2 cylinders than 1 when using the starter. I ran it that way for many miles and years.
     
    Jim and robinc like this.
  12. GLJ

    GLJ Never go faster than your guardian angle can fly. Top Contributor

    I just checked on partzilla and the 72, 75 and 78 650s show the same part number for the starter motors. I remember being told back in the day Yamaha considered it a failed experiment starting them on 1 cylinder.
     
    Jim likes this.
  13. Mailman

    Mailman Hardly a Guru Top Contributor

    I could see a well sorted bike with a good battery and compression firing off quick. I’m kinda in love with the quirky little finger lever being the starter button. Do you still use yours?
     
    Jim and robinc like this.
  14. Mailman

    Mailman Hardly a Guru Top Contributor

    Well that’s interesting. I always thought they made the motor more powerful in later years.
    There are several things about my model that Yamaha thought better of later on. The front disc set up especially.
     
    Jim and robinc like this.
  15. GLJ

    GLJ Never go faster than your guardian angle can fly. Top Contributor

    I still used the lever. Just the cable was removed.
    On a funny note now but not then the lever did cause me a small problem. I went down on the road one day. When I finally stopped sliding my left arm was caught up in the back wheel and the bike was on top of me. Adrenalin kicked in and I was able to somewhat stand the bike up. Could not get my arm out of the back wheel. Bike was in gear with only right arm could not role wheel backwards against motor. Young teenager cam running up to help. I told him to pull the clutch in. When he grabbed the handlebars he got a hold of the starter lever but not the clutch, those starter motors are more powerful than you think. I let out a blood curling scream, he turned white. He then got the clutch pulled in and I was able to role wheel backwards and extract my arm for bike. 3 steps latter I was flat on my back in the grass next to road waiting for ambo.
     
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  16. 5twins

    5twins XS650 Guru Top Contributor

    19,446
    10,820
    813
    I think they did make the starter motor more powerful after the 1st few years. The same part number for early and late ones probably simply reflects the current replacement part, now specified for all models. Most of the on-line parts places are like this. They list the current Yamaha parts. If you want to see what used to be used, download the actual parts manuals from the XSCafe. I do a lot of cross-referencing between them and the current part number listings to try and figure out if some parts have been changed.
     
  17. GLJ

    GLJ Never go faster than your guardian angle can fly. Top Contributor

    5t you may very well be right. And it would make sense that they retroed them back. I do know from first hand experience that it started better on 2 cylinders than 1.
     
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  18. 5twins

    5twins XS650 Guru Top Contributor

    19,446
    10,820
    813
    I imagine it would, lol. I think Yamaha also realized that the starter would crank both cylinders no problem without the need for the decompressor.
     
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  19. Jim

    Jim Beyond the edge, is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Check the end cap on the starter. Power rating should be cast into it. .5KW (about 2/3 HP.) at 12V on my SG starter

    1.jpg
     
  20. GLJ

    GLJ Never go faster than your guardian angle can fly. Top Contributor

    Not trying to take over your thread Mailman. Thought yours might still be packed away.
    It was a little dirty.
    11.PNG
    A little cleaner now. .5 KW
    12.PNG
     
    Jim likes this.

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