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Thread: 2 quick questions about piston rings

  1. #1
    zsnider
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    2 quick questions about piston rings

    1. What is the best way to check for cylinder roundness?

    2. What tool do I need to remove and replace piston rings?

    thanks Y'all
    ~Z

  2. #2
    Cam Killer marchyman's Avatar
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    Quote Originally Posted by zsnider View Post
    1. What is the best way to check for cylinder roundness?
    A dial bore gauge will let you check for taper and, by measuring at different spots, roundness. http://www.amazon.com/2-ENGINE-CYLIN.../dp/B000I8QVES for example. (I haven't a clue as to the quality of that set. It was just one of the first I found googling "dial bore gauge.)


    Quote Originally Posted by zsnider View Post
    2. What tool do I need to remove and replace piston rings?
    Fingers are popular. Or you can find something like this at your nearest auto supply store. For putting the cylinder over the piston fingers, again, are popular and recommended by some. I prefer what are sometimes called aircraft style piston ring compressors.

    // marc

  3. #3
    Cannonball Rider #52 darrylri's Avatar
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    I have used a hose clamp to compress the rings for piston installation. However, I have a nice ring clamp now that is much easier and quicker.
    --Darryl Richman, forum liaison
    http://darryl.crafty-fox.com

  4. #4
    zsnider
    Guest
    Fantastic! I was born with ten of the tools I need for this job. As for the Dial Bore Gauge I will probably call up some other motorhead friends to find one to borrow.

    Are there any visual indicators that would lead me to suspect an out of round cylinder? This '66 r50 has under 40K and everything looks good on the inside. I lost compression ( very suddenly) after replacing two old leaky head gaskets. I suspect that new rings will solve the problem.

    Again.
    Thanks Y'all

    ~Z

  5. #5
    DEDGCOMB141129
    Guest
    Check your valve guides!

  6. #6
    Enigma
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    Take the valve covers off. Bring piston to top dead center, so both valves are closed. Attached compressed air where the spark plug attaches. Increase air presure to about 50 / 60 lbs. & listen to where it leaks. If it's the valves you will hear it from there. If it's the rings, you will hear it from the bottom of the cylinder. This will at least point you in the correct direction. It is rare that a cylinder will go out of round suddenly. Sounds like the valves to me.....

  7. #7
    zsnider
    Guest
    I wish I could have gotten to this sooner but life sometimes gets in the way of measuring cylinder bore. any way, here are the specs.

    My left cylinder looks good and round and not worn. my right cylinder shown no unusual signs of wear but it is out of round in the top of the cylinder. The spec allows for .01mm of out of round and the longitudinal measurement shows .02mm different than the latitudinal measurement.

    All of my piston ring gaps measure right at .5mm and the spec. calls for .25mm-.4mm. ( they are just out of spec. )

    will a new set of rings be enough or do I need to re-bore my cylinders?

    RE my valve seats. I feel good about them being tight. I have checked for recession and wear. Also, one of the symptoms when I lost compression was a lot of blue oily smoke exiting my crankcase pressure relief outlet. Indicating to me that I have a piston ring blow-by problem.

    I'd love to hear your thoughts.

    ~Z

  8. #8
    Administrator 20774's Avatar
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    Z -

    Sounds like you're a little beyond even marginal. Since all the rings are beyond spec and you've got some ovality, my guess is you'd be better off going first over. Of course, that'll mean new pistons as well.

    Bore-Tech (http://bore-tech.com/) would be something to consider. They do good work and can put the carbide process in the bore to virtually eliminate wear.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  9. #9
    zsnider
    Guest
    I was just looking at bore tech...I will probably go that route. I guess the next thing to consider is do I upgrade to a high compression piston while I am at it?

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