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1981 GS650GL Bad compression results

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    #16
    Pulling the carbs is baby stuff compared to doing the valve stem seals. The gs850 is a great bike- a one owner with spare parts sounds like a deal
    1981 gs650L

    "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

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      #17
      In order to address the low hanging fruit I decided to take the GS650GL for a few more rides the past 2 weeks, riding it almost daily. This taught me a few things:
      1) It runs like ass when warmed up and idling
      2) It does not burn as much oil as when it was sitting for longer periods (no typical blue smoke in the morning during warm up on the center stand)
      3) It is a very nice bike to ride

      In order to address 1) I employed the low hanging fruit first method and bought myself a nice carburettor sync kit and looked up 2 resources on doing carburettor synchronization on Suzuki GS's. I used http://www.bwringer.com/gs/carbsync.html and http://www.thegsresources.com/_forum...re-on-CV-Carbs , with the latter for some more info on the pilot fuel / air adjustment. Well, it ran absolutely fine on 2 rotations out for each carburettor, so I left it at that. Next I synced the carburettors using the Morgan Carb Sync Pro, nice piece of hardware! After fiddling for a few hours with those annoyingly hard to get lock nuts I got them all nicely lined up in the "equalizer smiley face" kind of setting (outer two carburettors having a slightly higher vacuum reading, but not much!). Checked if it still ran fine with the pilot air/fuel setting and it seemed OK. Small testride later and I was pretty much blown away by the difference at idle. Very nice and smooth idle, regardless of it being warmed up or not. Another surprise was it needing actual choke to keep going at start, just like my previous GS450E. Once warmed up it does not need it at all, but the choke used to be useless after starting, making it race in rpms almost instantly after starting (even with a little choke). Starting the bike is also a lot easier than it used to be, but that could also be due to the more regular driving. I should add that the original carburettor setting looked like a hacksaw, #1 pulling twice as much as #2, #3 being as high as #1 and #4 being low again, around the same level as #2. Or a reverse sawtooth wave if you will.

      For 2) I am not sure what is going on. It pretty much always sits on the centerstand nowadays and is driven more frequently. Oil levels are still at F so... not sure what is going on there. No more blue smoke though, but it still stinks Perhaps it is running still a little rich.

      And 3) should speak for itself. I like how easily it corners and how linear the powerband is. It is a very comfortable bike in the current nice weather on the highway. I only miss a windscreen, which would be nice at the 70-80 mph bits when there is a bit of wind.

      Not related to the above: The GS850G had quite a few minor defects and it being highway distances from home without having an option to move it by other means. Had to leave it there unfortunately... A pity, the owner was a very nice guy and cared for his bikes, but just could not anymore and had been holding onto it for a few years with it just sitting in the shed. It ran rough idle (petrol gunk had already been removed from the tank) and the right front fork had sprung a pretty big leak with fork fluids all over the right front disk brake. I suppose that happened during his test ride as the forks had some nasty rusty bits on them. Currently looking into the Yamaha XJ series (650 - 750 - 900) as the series has a great following here in NL, but keeping an eye on the second hand marketplaces for any GS650 and up.

      Edit: And the BMW K series adventure? Well it is a driving fortress. Nice for when you drive long highway distances, but the fun factor is just gone with them. They're ultra practical and not more, not less. The ones I checked out had ridicules ammounts of rust (being driven daily and sitting outside all their lives, well over 150K km's for each!). I think I prefer bikes that sit in a shed when not used, just like my own. It keeps them nice. Having driven around on a GS850G, GS650GL, XJ900 Diversion and XJ650 Seca the BMW K-series are just... practical. Perhaps I do have a little more ego than I thought, as I did not really like the idea of me driving around on such a cathedral. Perhaps the R-series is better suited to my taste.
      Last edited by Tijmen; 06-22-2017, 06:30 AM.

      Comment


        #18
        Nice to see that you have had some progress here, but one item in your report leaves me with questions.
        Originally posted by Tijmen View Post
        1) It runs like ass when warmed up and idling.
        When my ass runs, it's not very pleasant. No details necessary other than that it's a medical condition that needs to be fixed.

        When an ass (a donkey) runs, it's also not very pleasant, but that's because it's very bumpy and uncomfortable.

        What is your version of "ass"?

        .
        sigpic
        mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
        hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
        #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
        #2 son: 1980 GS1000G
        Family Portrait
        Siblings and Spouses
        Mom's first ride
        Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
        (Click on my username in the upper-left corner for e-mail info.)

        Comment


          #19
          Originally posted by Tijmen View Post
          I am a bit skeptical about rebuilding the carbs, it all looks a little crusty and I fear I might strip the heads.
          Use a proper JIS screwdriver, (NOT a Phillips), should be ok.

          Originally posted by Tijmen View Post
          I think it is not uncommon to replace the boots as well? The rubbers between the carbs and the cylinders that is.
          If they are hard or damaged, you should replace them.
          At least replace the o-rings between boots and cylinder head, they are cheap.
          CMSNL sells them, as does CycleOrings.
          CycleOrings also sells all needed o-rings in a nice set.

          Have you tried to spray starter fluid or brake cleaner on the connection between
          boots and cylinder head ?
          If that changes rpm, they are leaking.
          Last edited by Rijko; 06-22-2017, 10:31 AM.
          Rijk

          Top 10 Newbie Mistakes thread

          CV Carb rebuild tutorial
          VM Carb rebuild tutorial
          Bikecliff's website
          The Stator Papers

          "The thing about freedom - it's never free"

          Comment


            #20
            Originally posted by Tijmen View Post
            Mods / Admins: Is there a way to rename this thread? The subject should be about oil burning, not so much compression loss I realize now. Sorry for the inconvenience
            if you edit your post, click 'go advanced'.
            That gives you the option to rename the title.
            Rijk

            Top 10 Newbie Mistakes thread

            CV Carb rebuild tutorial
            VM Carb rebuild tutorial
            Bikecliff's website
            The Stator Papers

            "The thing about freedom - it's never free"

            Comment


              #21
              Originally posted by Rijko View Post
              if you edit your post, click 'go advanced'.
              That gives you the option to rename the title.
              Thanks, renamed it to rough idle because that is what the issue is.

              As for the bike: it is now a little choke reliant, like my old GS450E, maybe even more so. The idle it has when warmed up is still off to me, seems like some cilinders aren't pulling their weight.

              Checked the ignition circuitry today, since I didn't really go through that last time. Primary coil windings are +-5 ohms (little less), secondary windings both floated around 25 k ohms. Pickup sensor(s) had a nice 325 ohms going for them. Battery under load dipped to 11.8V, so it was time to put it on the charger again. Perhaps the charging circuit is bad? Could that cause problems when the bike is warmed up?

              The plugs in all likelihood still get gunked up, but as before it doesn't burn that much oil anymore, since it is chilling on its centerstand now. I'd really like to solve the issue once and for all, but it would be great if someone with more experience could assist with the fuel delivery system. My past experiences with that... in combination with a 2 stroke... were not too good, never got it perfect.

              As for the new bike, I am sorry to inform GSresources that it is a Yamaha XJ900F from 1987. The GS850G was in a little rough shape, lots of small leaks and also running not quite right. Since I can't even make the GS650GL proper in my spare time I wasn't really too happy to try that with my daily driver.

              @Steve: the first definition is quite fitting, replace ass with GS650GL and you got my meaning . Thank god it behaves normally on the highway and sorts, only with the recreational driving is the rough idle is an issue.

              Comment


                #22
                Progress is always nice...

                "Battery under load dipped to 11.8V, so it was time to put it on the charger again. Perhaps the charging circuit is bad? Could that cause"

                Fix your charging system..the ignitor might misfire if voltage feeding it gets low while running.

                As for yamaha..folks here have lots of different bikes, so no problem! No sense buying a beat up suzuki when better stuff can be had.
                1981 gs650L

                "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

                Comment


                  #23
                  I've had a few XJ900's in my time and they are terrific bikes. Very underrated compared to the other big bikes of the day and the motors are bulletproof.

                  They were also a one year only release in the US so quite a few people here will be envious of you.
                  Current:
                  Z1300A5 Locomotive (swapped my Intruder for it), GS450 Cafe Project (might never finish it....), XT500 Commuter (I know - it's a Yamaha )

                  Past:
                  VL1500 Intruder (swapped for Z1300), ZX9R Streetfighter (lets face it - too fast....), 1984 GSX750EF, 1984 GSX1100EF (AKA GS1150)
                  And a bunch of other crap Yamahas....

                  Comment


                    #24
                    In case anyone in the future happens to find this thread: most of the problems have gone away. Perhaps an easy fix in hindsight, but after changing the oil and oil filter the motorcycle has been running a lot cleaner (read: no burning oil, no rough idle issues). Just because you don't drive a lot doesn't mean the oil stays good, or so I have heard. Other than cleaning it, new air filter, synching the carburettors, fresh oil and the valve adjustment nothing big has happened to it. So do your regular maintenance!

                    I don't drive it as much as I should, my XJ serves me well with the 3 piece storage on the back and fairing to keep me from getting blasted on the highway. But every now and then we spin it up and go for a ride together and it, the GS650GL, has never let us down.

                    Comment


                      #25
                      The GS650GL is still going strong! After installing a new battery all of the electrical issues have gone away, perhaps it is masking the poor charging circuit... but I digress, it is doing well. As long as it keeps being reliable up to ~300KM of travel it is doing its job.

                      In the mean time a lot of things have changed in the garage. My trusty old XJ900F has become my father's first motorcycle and I have given myself a nice XJ550 Seca from 1981 and a Ducati Monster 900ie from 2001. The desmodromic valves on the Duc are very interesting and it drives like a treat. Both bikes are a lot of fun, in their own way. But, the GS's have always had a special place in my heart since I had the GS450E.

                      A few weeks ago I have decided to give in and get the bike I have always wanted: a GS850GN from 1979. It's a puzzle, literally. Bought it with an engine in a frame and two wheels attached along with a lot of parts in a few crates. Visually the bike is in a pretty darn good state for its age, with a lowish mileage of only 35000KM on the odometer. The most likely reason it has been parted is probably the destruction of its stator with nice black and crunchy wires coming from it. And yes, there is considerable resistance measurable between the three soot turned wires. I've done myself a favour and got me a new used wire loom (cable tree?). In due time I'll open another topic for it, for now I am busy removing the last pieces from the bike and breaking everything into small pieces so that I can inspect all the important bits to make it run again.

                      Points ignition, kickstart, 270+KGs of iron and aluminium hunks... I'm excited

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