Service-New to Me-'81 R100/t

Discussion in 'Airheads' started by brittrunyon, Apr 6, 2013.

  1. Plaka

    Plaka Brevis illi vita est

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    Turn it 180 degrees to the other TDC and look.

    Check radial slop in the sprockets.

    Did you already buy a chain and stuff?
    #81
  2. brittrunyon

    brittrunyon R 100 GS F 650 GS

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    Rotated 180
    ........OT mark back in window
    .......crank mark centered & pointing down
    .......cam dimple down but not centered

    & yes I have the parts but got the wrong sprocket.

    <a href="http://s1089.photobucket.com/user/brittrunyon/media/1981%20R100%20t/_DSC8985_zpsc2c4ec91.jpg.html" target="_blank"><img src="http://i1089.photobucket.com/albums/i358/brittrunyon/1981%20R100%20t/_DSC8985_zpsc2c4ec91.jpg" border="0" alt=" photo _DSC8985_zpsc2c4ec91.jpg"/></a>
    #82
  3. Airhead Wrangler

    Airhead Wrangler Adios Mexico

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    What's that going to tell us?
    #83
  4. brittrunyon

    brittrunyon R 100 GS F 650 GS

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    :scratch
    #84
  5. Plaka

    Plaka Brevis illi vita est

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    markings might reveal what the last wrench did.
    #85
  6. Plaka

    Plaka Brevis illi vita est

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    bingo, there's the yellow paint. Someone was working 180 degrees around.

    I'd evaluate wear closely. if that chain is tight, Correct the one tooth issue and just button it up. Return the wrong sprocket, put the new chain in storage, you'll need it someday if you keep the thing long enough. You can go in again very quickly if you aren't happy. Whole lot quicker the second time. All you risk is a new gasket. No point replacing parts with lots of life left not to mention the extra work. It will make a nice rattle for you when it wants replaced. I'd use hylomar or similar on the gasket. Ultra blue silicone is pretty nice stuff too. Very thin coat.
    #86
  7. Airhead Wrangler

    Airhead Wrangler Adios Mexico

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    Where? :huh

    Working 180 degrees out doesn't matter as long as you're on the right tooth. If you time it 180 degrees around from the timing mark, it doesn't matter.
    #87
  8. Plaka

    Plaka Brevis illi vita est

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    Not so long as you match everything up. Don't see matching yellow paint. Also, using the existing marks is smart. Why not? Why did someone work 180 out?

    Make sure neither pully has an offset key in it.
    #88
  9. brittrunyon

    brittrunyon R 100 GS F 650 GS

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    The yellow paint & dark "burn" mark can be seem here, but one tooth left.
    Also, there is an obvious yellow mark on the crank right of the dimple. This confused me.

    [​IMG]

    When I go to line the marks up
    ........I'll rotate 180 and get the two marks closer together
    ........which sprocket do I turn? The cam clockwise or the crank counter clockwise?

    I've heard sealer on the gasket & I've heard no sealer?
    I have Yamabond 4

    The key on the cam looks good but can't see the crank key.
    #89
  10. Airhead Wrangler

    Airhead Wrangler Adios Mexico

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    Turn the crank clockwise with a bolt in the nose of it. When you pull the crank sprocket make sure there isn't an offset key like plaka was saying, but I'm guessing this is just a case of fucking up and being off one tooth. An offset key will put it off a few degrees which won't be so obvious when looking at the timing marks. A whole tooth out is too much to be an offset key. It is weird that someone wanted to make their own timing marks though.
    #90
  11. brittrunyon

    brittrunyon R 100 GS F 650 GS

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    Damn. Had my cam & crank switched in my head, thanks for straightening me out.
    #91
  12. Plaka

    Plaka Brevis illi vita est

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    Crank always at TDC, and you want that accurate. Match up the cam to that. It's a wasted spark system so it doesn't matter which side leads the show.

    Go light on the sealer, why I reccomended easy to remove stuff. I have no experience with the Yamabond. I'd go for a little extra besides just the paper, but not set yourself up for a hassle the next time you go in, either getting the cover off or cleaning the old gasket sealant.
    #92
  13. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    Oh. I see. ;)

    [​IMG]

    --Bill
    #93
  14. supershaft

    supershaft because I can

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    This is the second airhead here within a year or so that has had the cam one tooth off. You would think someone would notice the bike not starting well and running like crap? If I remember right, they won't even run with the cam off one tooth the other way?

    At any rate, the chain and sprocket are not worn enough for that to be the cause of the trouble. That crank sprocket is worn if I am seeing it correctly. I suspect the chain and guides were just replaced. It would be just fine to time the cam correctly and button it back up. I would be tempted to replace the chain and sprocket IF that sprocket is worn. There is no need to go looking for offset keys.

    I would install that gasket clean and dry.
    #94
  15. brittrunyon

    brittrunyon R 100 GS F 650 GS

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    When I purchased it last month I noticed that it had "funny" way of starting, not that it was difficult to start, just different from my "92 GS.
    On cold starts, even with the choke on, I had to open the throttle to prevent it from dieing. I thought it might be the carbs, but that's next. Has a stumble at 1200 rpms as well.
    On the road it's just powerless.
    And then of course "we" couldn't time it.

    I, with my eagle eye:D, see some wear on the crank sprocket. I know it's hard to diagnose looking at photos.
    If "they" indeed just replaced the chain & guides, wouldn't it be best to just do her right & refurbish for another 100k?
    The bearings feel fine.

    Or could I get another 50k the way it is now. Hmmmmmmmmmmmmmmmmm?
    Is it worn enough?
    [​IMG]
    #95
  16. supershaft

    supershaft because I can

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    100k miles out of an airhead timing chain? Good luck! Your going to need it but then again a lot of airhead owners don't mind their airhead clinking and clacking and running like crap while it shakes and shutters and pukes oil all over itself. It seems as if some airhead owners are kind of proud of just how bad their airheads can look and sound and still just barely run.

    A entirely new setup will need replacing in 60 or 80k if you want it to sound and run like a top. New chains on worn sprockets should be good for 30 or 40K?

    I would get your chain and sprocket from a dealer. There are junk chains out there!
    #96
  17. Plaka

    Plaka Brevis illi vita est

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    What does the pluck-the-chain test reveal?

    I already bet myself an ice cream bar on what you're going to do. At 5k a year 50000 miles is ten years. You won't consider this.
    #97
  18. Plaka

    Plaka Brevis illi vita est

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    Root of a negative number. Creative. Makes things more complex but nothing a good imagination can't handle. Didn't you mean to post over in the "Bird Strikes" thread in Perfect Line...
    #98
  19. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    Whoosh.
    #99
  20. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    Yep, that sprocket is done wore out.

    Just last month? A lot has happened...

    --Bill