Announcement

Collapse
No announcement yet.

Compression Test 140-120-35-120

Collapse
X
Collapse
 
  • Page of 1
  • Filter
  • Time
  • Show
Clear All
new posts
Previous template Next
    #1

    Compression Test 140-120-35-120

    I have been trying to get my 1980 GS750L running for awhile, I did the Carb cleaning thing and it would only run on choke. I just did a compression test and I got 140-120-35-120. I know the answer is probably rings or valve seats, but was hoping someone here might have an idea that doesn't include a rebuild. I checked the valve lash on the bad cylinder and it had at least 0.004 in. when the cam lobe was opposite the valve plate. Any ideas?

    Brian
    Tags: None
    #2
    Pour a little oil in the 35 psi cylinder and see if the number rises. If it does it's probably rings. Did the bike sit for awhile?
    1983 GS 1100E w/ 1230 kit, .340 lift Web Cams, Ape heavy duty valve springs, 83 1100 head with 1.5mm oversized SS intake valves, 1150 crank, Vance and Hines 1150 SuperHub, Star Racing high volume oil pump gears, 36mm carebs Dynojet stage 3 jet kit, Posplayr's SSPB, Progressive rear shocks and fork springs, Dyna 2000, Dynatek green coils and Vance & Hines 4-1 exhaust.
    1985 GS1150ES stock with 85 Red E bodywork.

    Comment

      #3
      The bike sat for some time before I bought it for $450, not sure how long though.

      Brian

      Comment

        #4
        Your rings might be froze up. You might be able to free them up with some penetrating oil.
        1983 GS 1100E w/ 1230 kit, .340 lift Web Cams, Ape heavy duty valve springs, 83 1100 head with 1.5mm oversized SS intake valves, 1150 crank, Vance and Hines 1150 SuperHub, Star Racing high volume oil pump gears, 36mm carebs Dynojet stage 3 jet kit, Posplayr's SSPB, Progressive rear shocks and fork springs, Dyna 2000, Dynatek green coils and Vance & Hines 4-1 exhaust.
        1985 GS1150ES stock with 85 Red E bodywork.

        Comment

          #5
          Most people wouldn't, but I'd pour some Marvel Mystery Oil in there, turn it over by hand a few dozen times, let it sit overnight and then- stomp the ever loving sh!t out of it the next day.
          Currently bikeless
          '81 GS 1100EX - "Peace, by superior fire power."
          '06 FZ1000 - "What we are dealing with here, is a COMPLETE lack of respect for the law."

          I ride, therefore I am.... constantly buying new tires.

          "Tell me what kind of an accident you are going to have, and I will tell you which helmet to wear." - Harry Hurt

          Comment

            #6
            Originally posted by Jethro
            Most people wouldn't, but I'd pour some Marvel Mystery Oil in there, turn it over by hand a few dozen times, let it sit overnight and then- stomp the ever loving sh!t out of it the next day.
            I like your style. What have you got to lose except a little metal[-o<

            Comment

              #7
              where buy MMO?

              where do you buy this Marvel Mystery Oil? Sounds like something I could use. Napa, Walmart?

              Comment

                #8
                Both probably carry it. I have picked it up at AutoZone.

                Rick

                Comment

                  #9
                  The MM oil is a good suggestion, sometimes.

                  My 1971 Honda SL175 has MM oil in it for the past 2 weeks, and is still froze up. Looks like a total tear down is in order.

                  Oh well, it will give my son something to do and hopefully keep him out of trouble for a few weeks.:-D

                  peace,
                  michel

                  Comment

                    #10
                    Originally posted by bjmorel
                    I have been trying to get my 1980 GS750L running for awhile, I did the Carb cleaning thing and it would only run on choke. I just did a compression test and I got 140-120-35-120. I know the answer is probably rings or valve seats, but was hoping someone here might have an idea that doesn't include a rebuild. I checked the valve lash on the bad cylinder and it had at least 0.004 in. when the cam lobe was opposite the valve plate. Any ideas?

                    Brian
                    Dont know if your bike has the vacuum hose for the petcock going to #3 carb. If it does and the diaphragm is ruptured in the petcock, cyl #3 may be washed down with fuel. Block off the fuel going to the carbs, drain the float bowl for #3, do the overnight MM oil soak and see if your compression comes back up....If not, do a leak down test.......BadBillyB

                    Comment

                      #11
                      On the 80 it connects to the #2 carb. Which carb is it if you go 1-4 left to right sitting on the bike?
                      1983 GS 1100E w/ 1230 kit, .340 lift Web Cams, Ape heavy duty valve springs, 83 1100 head with 1.5mm oversized SS intake valves, 1150 crank, Vance and Hines 1150 SuperHub, Star Racing high volume oil pump gears, 36mm carebs Dynojet stage 3 jet kit, Posplayr's SSPB, Progressive rear shocks and fork springs, Dyna 2000, Dynatek green coils and Vance & Hines 4-1 exhaust.
                      1985 GS1150ES stock with 85 Red E bodywork.

                      Comment

                        #12
                        Number 3. The Vacuum is on number 2, but it is plugged right now.

                        Comment

                        Previous template Next
                        Working...
                        X