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Thread: Valve issue help (video)

  1. #16
    Registered User ebeeby's Avatar
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    Quote Originally Posted by Guenther View Post
    Sometimes it is too obvious to NOT turn over the motor again!

    Attachment 77380

    /Guenther
    Yikes!
    1973 R75/5

  2. #17
    Registered User STEVENRANKIN's Avatar
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    Time

    It does not take a lot of time or effort if one knows what one is doing and has the proper tools to pull off the valve rockers, or even the head to see what is wrong. Could be something simple, might not be.

    Takes a lot more time to repair a broken con rod or crank, pistons and such are expensive things to knock holes in if loose bits are in the combustion chamber or a stuck open valve.

    I would rather spend an hour and the cost of a new head gasket than running an engine and perhaps causing more damage. St.

  3. #18
    Nick Kennedy
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    Guenther
    That's a great photo
    A little JB weld and I bet he'd be ready to ride the next day!

  4. #19

    A dislodged valve seat maybe?

    Just a thought and a clear reason why you really don't want to run it or turn it over for a compression check or even bother with a leak down both of which could come back fairly normal. The valve seat migration would explain the additional clearance, the rocker arm slapping the top of the valve as it travels to open the valve all the while the bike idles pretty good and doesn't have any serious oil leakage. You run that motor or turn it over for a compression test and you very well could knock the valve seat out enough to cause the piston to hit the valve on the compression stroke. You would be lucky to get away with a dented piston dome and a bent valve but may go as far as bending a rod, or some other more serious damage.

    If your on the fence with this just do the math.

  5. #20
    Registered User toooldtocare's Avatar
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    My bet is also a stuck valve. Iíve had this on an English car (AH Sprite) where the shop that did my head work did not open up the new guides enough. There was no damage, but there could have been. My compression gauge has a regular Schrader/pressure release valve that I can connect a pump to. I used it to do a simple leak down test by threading the gauge into the spark plug hole and used a bike pump to apply pressure. If the valve is open you will not be able to build up any pressure. From the video it appears the other valve is closed.

    Or, just remove the head to access the damage. I agree with the others, donít spin the engine over further until you find out the cause of the loose rocker.

  6. #21
    Rally Rat 1074's Avatar
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    Playing the guessing game

    I can't believe the variety of guessing games being played here. The fact that there is a clanking noise tells me that you are going to have to take it apart sooner or later!
    So an inquisitive diagnostic mind would say that with the valve cover off and the rocker arms removed, you might probably find a stuck valve.
    But then again, even if that is what is wrong, you're going to end up pulling the whole top end anyway. So taking it all apart makes total sense. Be sure and remove the lifters as well. So then you have the whole picture and can figure it out from there.
    Boxerbruce

  7. #22
    Rally Rat 1074's Avatar
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    Video

    Forgot to mention that from the video it looks like a stuck valve, or a broken lifter but I wouldn't want to guess about anything.
    Boxerbruce

  8. #23
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    Exactly why I wouldn't rush in and pull the head. Nobody here has a idea what is the issue.
    Connect compressed air in the spark plug hole and see if it comes out the intake. Pull the intake and you should be able to see if the valve is open.

    My point of contention is the guys that just want to start tearing it a part when there is no confirmation what the is problem.
    From the only real Fargo, ND!

  9. #24

    Exactly right because the problem is obvious

    I stand by my previous suggestion that you compare the valve train operation to each other by slowly rotating the motor by hand (battery disconnected, front cover off) and determine if you issue is a stuck valve or a problem with the push rod, rocker arm or lifter. Before you go start "tearing it apart" check and adjust your valves and give it a few more spins by hand, there's a lot of space in between the adjuster and the top of the valve stem so it might just be a practice run on valve adjustment. Regardless of where the problem is you will at least have to pull the left side cylinder head to ensure you find the route cause of the problem and fix it correctly.

    There is no mention of the bike running rough or on one cylinder during the "clack clack" noise so I would have to assume the valve is at least closing down on its seat. That is why with the information provided I think it might be a dislodged valve seat. If it did run rough or on one cylinder it could be a broken push rod, lifter, rocker arm, pulled cylinder stud, bent or broken valve stem or maybe something is stuck in between the seat and valve holding it open. So if you do tear it apart take a close look at the throttle plate of the carburetor to see if both screws are present.

  10. #25
    Registered User toooldtocare's Avatar
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    I had no idea that my suggestion to troubleshoot an issue would cause such a heated discussion. I am surprised. I spent my entire life repairing things, first aircraft (27 years, 16 military and 11 years civilian) and another 18 years durable medical equipment. I cannot imagine what a pilot, or a person relying on his respiratory equipment to breath, would think if I told him that I didn't know what the problem was, but I will rip it apart to try to find out what went wrong. I was taught to think, use the correct troubleshooting tools, and my education to analyze a problem before I tear it apart. It takes only a few minutes to pump some air into the cylinder to see if the valve is stuck. No damage would be done, and it could tell us a lot. So could ripping off the head, dropping the pan to look at the cam, remove the cylinders and pull the lifters to check them. However, that would require an rebuild, new parts, and a lot of work.

  11. #26
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    I go with "do not turn the engine over" period. Until you take that side apart. My uneducated guess, could be a collapsed lifter, busted.

    When I got my trashed R90 many years back, rode it one time. Quite noisy I thought? Both exhaust lifters were cracked, running in place, ruined the lifter bores and the cam surface. No biggie. Pulled the head and started ordering parts. But that's just one scenario. Good luck. Two cents.

  12. #27
    Registered User STEVENRANKIN's Avatar
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    Snap

    Let me clarify my comments.

    First, if there was no SNAP then clanky clank, I would not be so adamant about not running a compression test or running the engine. Loss of power on one side is one thing. A loud snap and clank is not. I can understand turning things by hand to compare sides and such as to see how one side functions versus the other. IF doing the turning by hand, resistance is felt, it can be stopped before something worse happens.

    If a leak down test or pressure test is done and the pressure holds or the test shows nothing, would I start the engine and run it? NO, not until I found out what went snap and clank.

    A snap and a clank means something will have to come apart at some time or another regardless if it is a stuck valve, broken pushrod, valve, valve seat what ever. Something will have to come apart and be fixed.

    I NEVER take things apart until I have to take them apart and sometimes, I have to take them apart to see what is wrong with them. I am not equipped with X ray vision. Nor do I have an X ray device handy. St.

  13. #28
    Nick Kennedy
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    Taking the Head and Cylinder off is pretty easy and quick; that's what I'd do. Then you could get to the lifters too.
    You could do all the work above slowly in about 30 minutes.
    I would not start it or even turn it over by hand but that's just me.

  14. #29
    Registered User Guenther's Avatar
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    All the experts have done their somersaults so far! Let's hear what chris.poole has to say.

    /Guenther
    2017 F700GS

  15. #30
    Registered User STEVENRANKIN's Avatar
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    Note

    I don't do summersaults.

    I try to help someone who asked for help/advice/opinion.

    I never claim to be an expert either, just someone with common sense and experience. St.

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