80 GS750L keeps dropping Cylinder #2..... No clue why

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  • NatiKiD
    #1

    80 GS750L keeps dropping Cylinder #2..... No clue why

    I have a 1980 GS750L that was sitting for some time. Well in the last 6 months I have brought it back to life. This issue started a few weeks ago. I just was out riding the back roads of Ohio... and the bike starting loosing power.. Would barely accelerate and would stall every time I would stop. Got home and the valve cover was just puking oil out the front. So I let the bike sit for about a week. Cleaned off all the oil. Started the bike... Only running on 3 cylinders (1,3, & 4). I have spark... So thought it was fuel related (carbs where professionally cleaned and rebuilt over the winter), took the carbs off and inspected #2 carb for issues. Took the jets out, sprayed carb cleaner threw the ports, and put it back on the bike. Still not running right. So I decided to adjust the valves (never been adjusted). All the valves where out of adjustment. Took the bike out on the road, and it ran great! All 4 cylinders firing and noticed a big difference in power. 2 days later, go to ride the bike... Its running great, 20 mins into the ride, I could feel a lost in power, and difference in the exhaust tone. Pulled over and #2 pipe is warm, and the other 3 are super hot. Went to ride home, prob. 3 mins before I got to my house, cylinder 2 came back, and it ran great. Went for a ride today... Same thing. Had all 4 when I left, 3 when I got home....

    Any ideas?

    On a side note, fuel has dumped out of the hose that is connected between carb 1 and 2 when running. Happened twice. Once when I just put the carbs back on the bike and the second time was when I was sitting at a stop light right before I got home.

    Here is my set up:
    Rebuilt carbs w/ Dynojet Stage 3 jet kit
    Straight pipes (no mufflers)
    Pod Air Filters
    Sportster tank w/ Harley petcock
    Tags: None
    • Guest
      #2
      Float level in carbs or a faulty petcock. Pull vacuumline off and check and see
      If it has fuel i. It. If it does that is your problem

        Comment

        • yoshisakan
          #3
          Check the resistance of your right side coil. Make sure its around 300 ohm. Also, unscrew the boot connected to the wire, and look for corrosion, if there is some, trim it back with wire cutters, reattach and you should be good.

            Comment

            • tom203
              Forum Guru
              Past Site Supporter
              • Aug 2010
              • 8925
              • Norway,Maine
              #4
              Check your oil level, maybe your harley petcock isn't right or your "professionally cleaned and rebuilt " carbs have bad needle seats and your crankcase is overfilled with fuel.
              1981 gs650L

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

                Comment

                • Guest
                  #5
                  Pull the vacuum line on the petcock and see if it has gas in it.

                    Comment

                    • NatiKiD
                      #6
                      Originally posted by yoshisakan
                      Check the resistance of your right side coil. Make sure its around 300 ohm. Also, unscrew the boot connected to the wire, and look for corrosion, if there is some, trim it back with wire cutters, reattach and you should be good.
                      Corrosion on coil side of the wire or plug side of the wire?

                      Thanks everyone for your input

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