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78 XS11 Smokes Terribly

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  • #1

    78 XS11 Smokes Terribly

    Hello all-
    New to the site, so I'll make this quick:

    I have a 78 XS11-E. Bought it cheap, known smoking problem. So none of this is a surprise, I figured it just had bad rings.

    The bike starts PERFECTLY. Excellent compression (at least it seems to be).

    Bike runs PERFECTLY, and smoke-free, anywhere from idle to 3,000 RPM. Doesn't miss, cough, or hesitate.

    After 3,000 RPM, the bike uses oil nearly as fast as it uses gas. A typical 100 mile jaunt will see 1-1.5 quarts of oil gone! Long, embarrassing blue trail follows.

    Can it possibly be the something other than the rings that causes this? I always thought if the bike started, ran and performed well it probably had good rings.

    If I ride that bike 40 MPH or less, it simply doesn't smoke. But when the tach hits 3k, it's got the worst blue cloud I've ever seen behind a vehicle.

    Air cleaner has oily substance in it.
    Plugs show that nasty black soot that comes from burning oil.

    I'm hoping I don't have to tear the darned thing apart, but if I do, I want to make sure I'm fixing the correct problem.

    I'd sure hate to rering the pistons and still have it smoke afterwards!

    Thanks everyone, this place rocks!

    -Kirt
    Tags: None
  • #2
    The bike starts PERFECTLY. Excellent compression (at least it seems to be).
    What is "Excellent"? Have you verified it with a compression gauge? What are the readings?

    Check your crank case vent to make sure it's not plugged. It's possibly building up pressure in the crankcase due to normal blow-by and forcing oil past the rings.
    Brian
    1978E Midlife Crisis - A work in progress
    1984 Kawasaki 550 Ltd - Gone, but not forgotten

    A married man should forget his mistakes. There's no use in two people
    remembering the same thing!

    Comment

    • #3
      I haven't checked the compression with a gauge (at least not yet). I wish I had, now that I've gone and posted my problem!

      I blew some air through the hose that runs from the rear part of the engine to the air cleaner box, and it was clear.

      There WAS oil present, but not as much as I would have expected with such a horrendous oil burning problem.

      Thanks for the reply!

      -Kirt

      Comment

      • #4
        just checking

        Check to make sure there is no gas getting in to your oil and that its not overfull as this will cause smoking. If u have good compression it does not mean that the oil rings are good . That said there could be bad valve seals or dry brittle valve seals that are letting it blow oil by. Sorry i cant be more help but it is not a simple problem where as it dosent smoke below 3000 rpm ....WEIRD......MITCH
        Doug Mitchell
        82 XJ1100 sold
        2006 Suzuki C90 SE 1500 CC Cruiser sold
        2007 Stratoliner 1900 sold
        1999 Honda Valkyrie interstate
        47 years riding and still learning, does that make me a slow learner?

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        • #5
          Yeah I know... that's what's baffling. If it smoked all the time, then I'd just tear it apart and replace the rings/seals, and I'd know it would be done.

          Instead I have to sit here and second-guess myself... not fun!

          Thanks for your help! I'll be tearing into it when I get home again... I'll post the results in case this should befall someone else later on.

          -Kirt

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          • #6
            When you check the oil level through the sight glass on the right side, are you checking it while the bike is on the sidestand or on the centrestand?
            Ken Talbot

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            • #7
              If the smoke increases when you close the throttle, it's bad rings. If there's no difference open or closed throttle, it's bad valve seals.

              Comment

              • #8
                OK, that sounds more like it than rings. It seems like it doesn't smoke quite as bad when you close the throttle (for example, slowing down for a stop sign, etc). But it's a constant blue cloud when you drive down the highway.

                Thanks for the info!

                -Kirt

                Comment

                • #9
                  Originally posted by Ken Talbot
                  When you check the oil level through the sight glass on the right side, are you checking it while the bike is on the sidestand or on the centrestand?
                  Good question Ken. Reminds me about the time my dad bought a car without a dipstick that smoked. He drove the thing to the nearest oil change place and had them drain the oil. He got cursed by folks the entire way there because he was blowing so much oil out of the car.

                  There was about 12 quarts of oil in the thing. The PO had been adding oil for a long time because the car burned it but he had no idea how much oil was in the car!!

                  Kirt, if the bike is on the sidestand when you check the oil, you have way too much in it!
                  Don
                  99 Valkyrie Interstate named Drakker

                  81 XS1100 H Peppylebleu sold and gone to a good home

                  81 XS1100 Midnight Special Peppyledeux sold and gone to another great home

                  Comment

                  • #10
                    Ha!

                    Thanks, guys, I make sure to always have the bike level when I check the oil.

                    I grew up working on engines both large and small with my dad, but this one seemed to stump the both of us so I thought I'd get a little assistance from the group that would know best.

                    I really do appreciate all your input!

                    -Kirt

                    Comment

                    • #11
                      Hey Kirt,

                      Like Mitch said, you'll want to check QUICKLY BEFORE RUNNING IT AGAIN, to verify that there isn't any gas in the oil. Stick a metal stick into the oil filler spout, then pull it out and step a ways away from the bike, then take a match or lighter to the oil on the stick, IF it lights, then it's gotten contaminated with gas....a common problem with these bikes after they sit a while, the petcocks leak, the float valves don't keep the carbs sealed, and they flood, flowing into the intake, into the cylinder thru a partially open valve, past the rings and into the crankcase. With the oil thinned, it will more easily leak past the rings back into the combustion chamber, adding to smoke! However, this problem will be preferable to having to redo topend rings and valves!

                      OEM oversized pistons and rings are not available anymore, so you would have to do the BIG BORE if you need new rings!
                      T. C. Gresham
                      81SH "Godzilla" . . .1179cc super-rat.
                      79SF "The Teacher" . . .basket case!
                      History shows again and again,
                      How nature points out the folly of men!

                      Comment

                      • #12
                        Oh man, I didn't know that I guess... I'd almost be better off finding a decent used motor if that was the case... might end up being cheaper

                        Thanks!

                        -Kirt

                        Comment

                        • #13
                          Holy Smokes!

                          Had a machine in the shop this morning with gas in the oil. At idle and slightly above, no probs. But rev it a little higher... and it smoked more than I do!
                          "Damn it Jim, I'm a doctor, not a mechanic!' ('Bones' McCoy)

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                          • #14
                            Yeah, sounds like that's what I'll have to check for. If I wasn't leaving for Dallas in 7 hours, I'd do it right now!

                            Thanks for that- as I said earlier I'll keep everyone posted as to what I find!

                            -Kirt

                            Comment

                            • #15
                              Hmmm, I was thinking it was the opposite, Randy. Of course I am no mechanic!!!

                              Originally posted by randy
                              If the smoke increases when you close the throttle, it's bad rings. If there's no difference open or closed throttle, it's bad valve seals.
                              Skids (Sid Hansen)

                              Down to one 1978 E. Stock air box with K&N filter, 81H pipes and carbs, 8500 feet elevation.

                              Comment

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