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Gotta weird one

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  • Gotta weird one

    so, after nearly 10 years of not riding, I finally got the old bike going again. Put about 7-800 miles on it over the past month, and two weeks ago it started something odd. Cruising along, 3rd or 4th gear, 40ish mph, and it starts acting like it’s running out of gas, only it isn’t. I can hold the throttle open to keep rpm’s up, and I can maintain speed, but that’s about it. After a few minutes it straightens out. May take an hour-ish to start happening, once it starts, it’ll repeat every 5-10 minutes. Changed fuel filter, took out fuel tap, and checked inside the tank, all good. One time I was in a group and the guy behind me said it sounded even from both exhaust pipes, and he smelled gas. So, I changed coils. No difference. If it was a fuel pump, one side of the exhaust would be fine, so it’s not that. I’m pretty sure it’s electrical, but not sure what would be that intermittent. Sitting still in interstate traffic at 95 degrees it’s fine, I’m always moving somewhat when it starts.


  • #2
    Hey Pete!

    I'm no expert, but I'd guess Culprit #Uno is the carbs.

    Do the standard Seafoam for a couple tanks, then Techron for a couple tanks.

    Other than that, pull and rebuild.

    Disassemble, soak in Pine-Sol+Berryman's B12, replace soft parts.

    Hope it's an easy fix ...

    While I am master of my sword, I shall never think any man greater than myself.
    ~Eumenes of Cardia

    I'd rather wake up in the middle of nowhere than in any city on earth. ~Steve McQueen

    I work over by worlds of fun. ~JimmyMac

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    • #3
      Those were the culprits originally. Rebuilt them, including ultrasonic cleaning, following a sea foam bath, new jets, new floats. I’m not ruling them out, since I obviously don’t know what’s wrong, but I really don’t think that’s it. It seems even across all cylinders, so for each carb to have the same intermittent issue seems unlikely


      • #4
        Does the bike have an alarm/immobilizer?

        Mine caused the bike to cut off at speed. Usually after 20 miles or so... Had to replace the tilt sensor to fix it...
        “Live a good life. If there are gods and they are just, then they will not care how devout you have been, but will welcome you based on the virtues you have lived by. If there are gods, but unjust, then you should not want to worship them. If there are no gods, then you will be gone, but will have lived a noble life that will live on in the memories of your loved ones.”...Marcus Aurelius, Meditations


        • #5
          Nope, but I am thinking electrical. A buddy gave me a voltmeter with alligator clips to attach to the battery, so I’m going to see if there’s a voltage drop at battery when/if it goes into condition again. I’ve heard some horror stories about tracing things like this....


          • #6
            I’ve got something similar on my ZX14. After an hour or so of highway riding the bike starts to cut in and out erratically. I’m thinking electrical / fuel delivery / engine management. The lighting, signal lights, hazard lights, clock etc aren’t affected. On my bike I’m thinking ECU, fuel pump or power commander.

            "I tried being reasonable, I didn't like it!"


            • #7
              Mine isn’t ‘jerky’, like momentary ‘dropouts’, rather it’s a few minutes of lowered power with the feeling it’s running out of gas. It’s not fuel supply, as the exhaust smells of fuel, so it’s getting gas but not burning it. Now though, I read the clutch plate scoring issue, and have to address that tomorrow first, then hopefully I can ride it with the voltmeter hooked up to see if that tells me anything.
              Once it starts acting up, it seems to go in regular intervals of running badly, then fine, badly then fine. Maybe 3-5 minutes of each.
              Last edited by petezzr; 10-05-2019, 11:03 PM.


              • #8
                Just curious.. have you done a plug chop?
                Young riders pick a destination and go. Old riders pick a direction and go.
                A motorcycle can't sing on the streets of a city.


                • #9
                  A plug chop? No idea what that is, so I doubt it
                  Rough order of events:
                  bike sat in garage neglected 10 year +\-. Long story.
                  rebuilt carbs, as listed above. After first install, bike started a few times, ran ok, then wouldn’t start again. Pulled carbs, floats full of gas, so replaced them. Failed to read instructions (man card intact), so had to pull the carbs again and actually adjust the float height. After about 4-5 tanks of gas, this problem happened the first time. Pulled tank and removed fuel tap, and check tank for debris. Clean as a whistle, so replaced fuel filter and went again. Same issue at the place on my commute home (very weird, same spot, but after an extended stop on the highway waiting for traffic, so a longer elapsed time). That weekend I went on a ride with a bunch of guys. Step one was 45 mins to the initial meeting spot, step two was up through Dahlonega to Suches across from TWO, again no issue. Step three was a stop further north somewhere. During the next phase, headed over to Helen, it started. Keeping the RPMs up, I could keep it running, but no real acceleration. After 5 minutes that felt like an hour, it smoothed out and I had full response...for 10-15 minutes, then it repeated. Then again once more as we got to Helen. After lunch we all went our separate ways. I took the straight shot to I-985 and south towards home and it happened twice more. The last time I was cruising about 10 over, and when it happened I was able to just about maintain that speed at WOT. Changed the coils, and commuted the next day, and the same thing happened on the way home, only sooner than before.
                  probably tmi, but I write all this in case it triggers a clue for someone...
                  thanks again!


                  • #10
                    Good luck getting it sorted. I hate chasing intermittent problems.

                    "I tried being reasonable, I didn't like it!"