GS850 Fix-up

Discussion in 'Old's Cool' started by Triam, Jul 4, 2013.

  1. Triam

    Triam Machinist

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    Ok, so I've bought a 81 GS850G and I'm fixing it up. When I bought it it squeaked especially at very low RPMs, even more so when the bike was only turning over. It had a knock so I took off the cover and checked the valves. Every single valve was out. [​IMG] maximum clearance for this bike on both exhaust and intake is .003, and I had one at .011 :eek1 Tomorrow I'll go and pick up new shims.
    Point #1 The person I bought it from said that he'd ride it for a while and then it'd bog down and die and then he'd let it cool off and it'd ride great again.
    Point #2 When I took off the valve cover most of the camshaft was bone dry. I coated the cams with oil manually, then the bike turned over much faster than before, and that squeak was much quieter. You can see from the picture of the cover that there was just debris that looked like worn shim and cam shavings, and you can see how dry it was.
    [​IMG]
    [​IMG]
    This is the top of the engine after my manual oiling job.
    [​IMG]
    Last fotos: cam shafts
    [​IMG][​IMG]
    [​IMG]
    So should I just assume that it's an oil pump problem, or clogged lines, or something else?
    #1
  2. Triam

    Triam Machinist

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    So, I forgot to mention that two of the 4 spark plugs were covered with oil when I pulled them, and I think they had less than 300 miles on them. Here's another picture:
    [​IMG]
    You can see the compression readings I got in the photo of the paper above, does this mean that I need to do a complete top end rebuild or is it the valve guides, or is this something that can wait until the end of riding season when having a bike that works isn't as important?
    #2
  3. Andyinhilo

    Andyinhilo Long timer

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    You definitely have an oiling problem. The early 4-stroke Suzukis were low-pressure, high volume systems, as all of the bearings, except the cams were balls or rollers. I would suspect a bad pump, or maybe a badly clogged filter. There is a flow switch on the crankcase behind the cylinder, and if that got stuck, it would starve the top end of oil, IIRC.
    #3
  4. Triam

    Triam Machinist

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    Thanks for the response.

    Accordingly I took off the oil pan to check the screen and it had a few bits of something black, but nothing that would block the flow. I cleaned them off with an air nozzle. The filter was a brand new K&N and the oil was also new. The flow switch has been seriously messed with so that it no longer works. I just ordered one today that's OEM. Take a look at the one that was on it.

    [​IMG]

    [​IMG]

    It didn't work because there was no oil flow past where the switch had been relocated Also, the switch was broken. :lol3

    I pulled the clutch so I could get to the oil pump and visually inspected the pump like it says in the Haynes manual. I found two nicks and I'm not really sure if they're the culprit or not.

    [​IMG]

    [​IMG]

    They look small to me, but I'm very new to bikes, so if those of you who know could shed some light on this I'd appreciate it.
    #4
  5. Triam

    Triam Machinist

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    K, so moving along.

    The manual says that there are supposed to be 2 dowel pins locating the pump, but they're not there on mine. I'm wondering if mine is a different pump that they went to later. It has a boss on one half of the pump and a relief to fit the boss on the other half. Did this year had that boss instead of dowels? Here's a picture of the two halves.

    [​IMG]

    I measured the oil pump and the clearances between rotors were fine. There's a measurement in the manual called "rotor endfloat" and I wasn't really sure how to measure it. I tried to imitate the picture and measured from the mating surface to the rotors. This measured out as .0055 and the "rotor endfloat" can be as much as .006, so maybe that's the culprit and I need a new oil pump. Here's the picture of how the manual shows it. I hope this isn't violating copyright.

    [​IMG]

    If anyone knows something that I'm missing please post! :ear
    #5
  6. willis 2000

    willis 2000 neo-quixote

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    hold the oilpump in yer hand
    rattle the shaft up and down
    if ya don't have the feel
    get a ruler so ya can hear the clack
    not likely yer only problem judgin' off them cam lobes
    musta been that valve ya spoke of and still bought it
    research after the fact
    that motor will either cost a lot
    or rattle and hum
    put it back together
    get it goin'
    resell

    credit u2
    #6
  7. willis 2000

    willis 2000 neo-quixote

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    fine pics
    #7
  8. willis 2000

    willis 2000 neo-quixote

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    tell me tell me
    wont't ya tell me
    and then tell me again
    wait this year out
    that old stuff, ya don't want it
    there's one in a museum or a coffee table book
    four of everything
    in the sixties, bill cosby revved us up
    everything's gonna be dual

    credit styx
    #8
  9. Triam

    Triam Machinist

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    What valve are you talking about? The oil pressure sender?
    Honestly, I'd rather do a complete rebuild than fix it and sell it. You saw my other thread. I bought it less to ride it, and more to have something to do. I've never done a rebuild, so it'd be fun. It'd run like a champ afterwards as well. Once this lube issue is fixed I'll step back and decide what the next thing is that I do. :evil
    #9
  10. joexr

    joexr Banned

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    Before you get any farther I'd find some local expertise. You may be barking up the wrong tree about an oiling problem . The cam lobes look good.
    #10
  11. willis 2000

    willis 2000 neo-quixote

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    this guy mentioned the flow switch.
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  12. joexr

    joexr Banned

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    Oil pressure switch.That's for the oil pressure light. Does NOT control flow.
    #12
  13. Triam

    Triam Machinist

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    The guy I bought it from said it developed the squeak recently, so that's why he decided to sell it. He didn't have time to go through it so he decided to sell it. I think that this is a new development so that's why the cams look so good. Local expertise would be nice. I don't know anyone local though.
    #13
  14. Triam

    Triam Machinist

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    Yep. Nevertheless, I ordered one because once I get everything put together it'll tell me if the problem is between the pump and the switch or between the switch and the cams.

    One more thing. I blew air through the oil passages (I don't know what they're really called) and I was able to verify that there wasn't anything clogging the system, or if there was it was blown somewhere else.
    #14
  15. joexr

    joexr Banned

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    It tells you the pump is pumping and nothing more.
    #15
  16. Triam

    Triam Machinist

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    I mean that if it says that it's pumping then the switch is getting oil which means I'm more likely to find my problem somewhere between the switch and the cams.
    #16
  17. joexr

    joexr Banned

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    .
    #17
  18. Triam

    Triam Machinist

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    When I took it apart it had been running just an hour before, and the cams were bone dry. Doesn't that sound like a lubrication problem to you?
    #18
  19. Triam

    Triam Machinist

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    The other thing I may have failed to mention is that with the cover off we turned the engine over, and still there was no oil on the cams.
    #19
  20. joexr

    joexr Banned

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    It'll take several seconds running at idle to get circulation. The cams look good. Whay do the tops of the buckets look like?
    #20