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GS 1000 '78, oil consumption

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    GS 1000 '78, oil consumption

    Dear all, I could use some help diagnosing the oil consumption on my GS1000 '78 — and discuss the possible remedies & their respective consequences.

    well: the engine uses oil. Between 2 to 4 liters per 1000km (0.5 to 1 gallon every 650 miles) depending on driving style. Highway driving (+130kph / +80 mph) uses a lot of oil!

    - the bike drives well, has good power, consumes about 7L/100km (33.5 mpg)
    - Last winter I changed the valve seals, they should be good.
    - valve clearance was checked last winter, before changing valves seals and clearances were good. Didn't recheck after changing valve seals.
    - valves + pistons had carbon buildup (hard, crystal like, black residue)
    - Compression, warm, throttle full open is close to 10.5 bar (145 psi). I don't trust the testers values too much, but the values are consistent. (might as well be 9 bar). Adding some oil to the cylinder and the values go up slightly to about 11 - 11.5 bar (160 psi).
    - I mostly drive in low rpms (3000-5000rpm), occasionally go to 7000rpm, never hit redline at 8500. It's an old lady. That said, I tried some italian tune-up lately; hard accelerating and engine braking in low gears, reaching close to red-line occasionally.
    - Tried full synthetic engine oil recently, which def did good on the gears. Engine subjectively ran smoother but oil consumption stayed the same.
    - Engine spills some oil from base gasket (between crankcase and cylinder block) at the front of the engine, right side. It's noticeable, the oil finds its was around the fans when driving, but it can't possibly explain all of the oil consumption. When taking the head off, the gaskets were a joke. Possibly the base gasket is f*cked as well.
    - Sometimes, friends mention some smoke coming from the exhaust. Not consistent though.
    - Poked a little camera through the plugs opening and the cylinders look good enough.
    - Don't know whether there's oversized pistons in there.

    I took over the bike about 4 years ago.
    The only thing that comes to my mind now is that the piston rings are shot. That's a hell lot of work to repair them.

    Could it still be something else?
    Anything to do or test before taking the whole engine apart?
    Could the rings just be stuck? How to get them loose?
    Are rings still commonly available for all of the piston sizes?

    Looking forward to your feedback!
    Last edited by Guest; 06-20-2017, 07:46 AM.

    #2
    Have you checked the breather hose? If it's blocked it could cause high crankcase pressure and oil consumption.
    -1980 GS1100 LT
    -1975 Honda cb750K
    -1972 Honda cl175
    - Currently presiding over a 1970 T500

    Comment


      #3
      Good one, thanks!
      will check and report back!

      Comment


        #4
        How much mileage on it? I would expect it to be smoking like crazy using that much oil... I had one that would use 200ml or so after 600 odd hard miles on the freeway but that had 80k+ on the original engine with nothing other than maintenance.
        1980 GS1000G - Sold
        1978 GS1000E - Finished!
        1980 GS550E - Fixed & given to a friend
        1983 GS750ES Special - Sold
        2009 KLR 650 - Sold - gone to TX!
        1982 GS1100G - Rebuilt and finished. - Sold
        2009 TE610 - Dual Sporting around dreaming of Dakar.....

        www.parasiticsanalytics.com

        TWINPOT BRAKE UPGRADE LINKY: http://www.thegsresources.com/_forum...e-on-78-Skunk/

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          #5
          That's a lot of oil consumption. If it was burning that much it would smoke like a public health hazard.

          If there is no (or little) smoke then and compression is as stated then I would think the bores, rings etc are okay.
          The continuing renovation of a GS850L

          Comment


            #6
            I checked the breather hose, it's open.
            Blowing in the hose builds up pressure and that pressure stays. Can't blow too much air in it, feels like it's connected to the cam shafts-cavities only. Can hardly imagine blowing air all the way to the crankshaft like that.
            Is the lower engine (crankshaft) connected to the breather and how?

            Originally posted by Tom R View Post
            Have you checked the breather hose? If it's blocked it could cause high crankcase pressure and oil consumption.

            Comment


              #7
              Tacho says 55000 miles. Could really be anything though.


              Originally posted by salty_monk View Post
              How much mileage on it? I would expect it to be smoking like crazy using that much oil... I had one that would use 200ml or so after 600 odd hard miles on the freeway but that had 80k+ on the original engine with nothing other than maintenance.

              Comment


                #8
                Originally posted by crookedspoon View Post
                I checked the breather hose, it's open.
                Blowing in the hose builds up pressure and that pressure stays. Can't blow too much air in it, feels like it's connected to the cam shafts-cavities only. Can hardly imagine blowing air all the way to the crankshaft like that.
                Is the lower engine (crankshaft) connected to the breather and how?
                Here's a cutaway view from the shop service manual. The cam chain tunnel is the air passage from the crank case, on up between the cylinders and into the top of the head. The breather sits right on top of the chain idler area of the cover.


                This is an 850 engine but similar in design.
                Roger

                Current rides
                1983 GS 850G
                2003 FJR 1300A
                Gone but not forgotten 1985 Rebel 250, 1991 XT225, 2004 KLR650, 1981 GS850G, 1982 GS1100GL, 2002 DL1000, 2005 KLR650, 2003 KLX400

                Comment


                  #9
                  Between 2 to 4 liters per 1000km
                  Without smoke? It's a gross engine oil leak.
                  Fibreboard on the floor, bike on centerstand and fire the engine up.
                  De-stinking Penelope http://thegsresources.com/_forum/sho...d.php?t=179245

                  http://www.thegsresources.com/_forum...35#post1625535

                  Comment


                    #10
                    So basically, if I'd remove the oilcap, I'd have to be able to blow straight through the engine. if not, something is clogged.


                    Originally posted by Burque73 View Post
                    Here's a cutaway view from the shop service manual. The cam chain tunnel is the air passage from the crank case, on up between the cylinders and into the top of the head. The breather sits right on top of the chain idler area of the cover.


                    This is an 850 engine but similar in design.

                    Comment


                      #12
                      The top end needs to be rebuilt. Most likely a bore job, new rings, valve job, and new seals and gaskets all around.
                      Ed

                      To measure is to know.

                      Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

                      Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

                      Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

                      KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

                      Comment


                        #13
                        Not sure a bore job but a top end rebuild for sure.

                        1980 GS1000GT (Daily rider with a 1983 1100G engine)
                        1998 Honda ST1100 (Daily long distance rider)
                        1982 GS850GLZ (Daily rider when the weather is crap)

                        Darn, with so many daily riders it's hard to decide which one to jump on next.

                        JTGS850GL aka Julius

                        GS Resource Greetings

                        Comment


                          #14
                          I don't see 67.6 to 135.2 oz of oil use per 620 miles driven in those cylinders. That's 1 oz of oil every 9.2 miles driven AT BEST.

                          Plugs do not show the shine from oil usage either.
                          De-stinking Penelope http://thegsresources.com/_forum/sho...d.php?t=179245

                          http://www.thegsresources.com/_forum...35#post1625535

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