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    Oversize piston rings

    So ive got to take the top end off the burgundy 1000C at some point to see why it has started to smoke rather heavily. So in anticipation of possibly some bore damage i was looking at the service manual. It says oversize rings are in two sizes. .5 and 1 over. Seeing ive not yet had to have a set of cylinders bored, my question is do they just bore them and i put oversize rings on the stock pistons or do i need oversize pistons too?
    MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
    1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

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    I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

    #2
    Pistons and rings. There's a good chance that the rings aren;t too bad - but the ring grooves wear. Excessive side clearance will make smoke.

    Many possible reasons for smoking as you know. Valve stem seals are the point to start looking.

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      #3
      As stated, look at the valve stems first. Re ringing works, but you have to take the cylinder head off, or at least the head, and have a good look at the cross hatching to see if they are worn smooth. Personally, If I was going through all that trouble, I'd buy a set of 1st over pistons with rings, refresh the cylinder head (new stem seals, valve guides, polish valves with rouge) and you will have essentially a new motor that you won't have to mess with a long time. You will have to replace the gaskets to check everything anyways, your major expensive will be buying the pistons bored and honed by a shop.

      Start at the valve stems first though. They can shoot out a lot of oil when bad. It could save you a lot of money.

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        #4
        If the bores are just glazed and a hone leaves the piston/bore clearance within spec you would re-use your pistons and just fit new rings of the same size.
        If the bores are worn and the clearance too wide to take a hone you would need a rebore and fit new pistons and rings of the next available oversize.
        Chances are though that the recent smoking is due to worn valve stem seals and possibly guides.
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          #5
          Stock pistons use stock rings, 0.5 over rings go on 0.5 over pistons. etc
          1983 GS1100E, 1983 CB1100F, 1991 GSX1100G, 1996 Kaw. ZL600 Eliminator, 1999 Bandit 1200S, 2005 Bandit 1200S, 2000 Kaw. ZRX 1100

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            #6
            My GS1000 had a smoke and oil burn problem. I fitted viton stem seals using the rope trick down plug hole. Seems to of done the trick, I've not had to top oil up in 1000 miles. It would have been on lowest mark before seals fitted.
            My bikes 79 GS1000 1085 checked and approved by stator the GSR mascot and 77 GS750 with 850 top end, GS850g, and my eldest sons 78 GS550, youngest sons GS125. Project bike 79 GS1000N

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              #7
              Yup, you need the matching OS pistons.

              Availability can be a problem; it has become very difficult to order these parts from Suzuki. Cruznimage has OS sets, though.
              Last edited by bwringer; 06-05-2023, 12:55 PM.
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                #8
                No matter what you end up doing, you do have to check the end gap on the rings.

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