Any 2 stroke experts out there

General Discussion

  1. ike61

    ike61 Well-Known Member

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    I have this coleman mini bike with a two stroke sachs motor. It runs great, but raw fuel drips out of the exhaust and makes a real mess.the gas is mixed 24:1, which is what is recommended. What could cause this? Thanks

    BC3FEB1D-32C7-4FD8-973A-5E62FBE458BE.jpeg
     
  2. 512Stroker

    512Stroker We are all here because we are not all there.

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    If it is fuel dripping out I would say you have a carb issue.
    What does the spark plug look like?
    2 strokes always run on the rich side
     
  3. ike61

    ike61 Well-Known Member

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    It will idle all day so i dont think its running too rich. The plug looks normal. I can run the hell out of it, but it still does it. I have an identical bike and that one does it too just not as bad
     
  4. George Jets

    George Jets 1967 Dart 2 Door FABO Gold Member

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    Needle and seat in the carb is leaking fuel past the seat, not shutting off the gas when the fuel bowls are full.

    Probably a piece of dirt stuck on the seat, clean the fines out of the fuel bowl and clean or replace the needle and seat with new.

    Also make sure the fuel bowl floats are set correctly to shut off the fuel when it reaches the proper level in the bowl.
     
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    • Dicer

      Dicer Diceman FABO Gold Member

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      If you have fuel tank shut off valve use it, if not buy an inline valve. Sounds like raw fuel draining from the carburetor into the crankcase area where it sits until the engine is started. The fuel not being atomized will be force out during the exhaust stroke. If the muffler has an inner baffle take it out and shine it up on the wire wheel.....check float...check needle valve and seat.
       
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      • George Jets

        George Jets 1967 Dart 2 Door FABO Gold Member

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        Yes, that inline fuel shut off in itself will probably cure it. Turn off the fuel when not running the engine.

        Clean out the bowl and needle and seat too.
         
      • ike61

        ike61 Well-Known Member

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        Ok. If the fuel was leaking past the seat, wouldnt it flood out while idling? I do shut off the fuel after each use because it will leak. It has a bing carburetor and i dont think the float can be adjusted. I will check on these ideas
         
      • famous bob

        famous bob mopar misfit

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        2 STROKES DO NOT ALWAYS RUN RICH as stated above , they run how they are adjusted/jetted . .
        I`d check the reed valve too--------------------------
         
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        • 512Stroker

          512Stroker We are all here because we are not all there.

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          You sure it not just condensation you see dripping.
          Collect some in a clear jar and see what you got
           
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          • cudavert

            cudavert DARTAHOLIC

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            If it was raw fuel, it wouldn't be running great. It would be flooded and barely running. I'll bet it's oil. My '75 Yamaha DT400 does that, drips oil out of the pipe.

            You could go up to 32:1 and lessen it....or even 40:1 or more.
             
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            • 1994redram

              1994redram FABO Gold Member FABO Gold Member

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              My Yamaha Banshee used to condensate really bad at idle. Revving it up would blast a nasty black water and oil concoction all over. And that quad was fast.

              I HIGHLY doubt its a carb issue. If the carb was bad enough to fill the intake, crankcase, cylinder, AND exhaust. It just wouldn't run....

              That's a cool bike with a sweet engine. I have a moped with a Sach's engine. Also have a Puch powered 'ped.
               
            • ike61

              ike61 Well-Known Member

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              Thanks. Yeah the kids love them because you dont have to shift. They are two speed automatic
               
            • ike61

              ike61 Well-Known Member

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              No its fuel/oil. Comes out at the end of the tail pipe, where the pipe joint is, and makes a damn mess
               
            • Bodyperson

              Bodyperson Pedal to the metal

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              Im guessing blow by. Looks like the case is leaking too. Who cares. RUN IT
               
            • Kern Dog

              Kern Dog FABO Gold Member FABO Gold Member

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              Any 2 stroke experts?
              Maybe ask some of the member's Wives!
               
            • Bodyperson

              Bodyperson Pedal to the metal

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              Exhaust could be getting plugged and running rich. Might try lowering the needle in the carb. I've taken an acetylene torch to the exhaust and burned out the carbon. Make sure your neighbors aren't home . lol
               
            • AJ/FormS

              AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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              Looks like sooty condensate to me. I used to see that all the time when I was in the business of motorcycle repair; even brand new ones did it.
              When the engine runs right, the exhaust is full of water-vapor, as a byproduct of the energy conversion process. You can see it every morning in cool weather when you warm up your car.

              Your exhaust system is running too cool for too long. Suzuki solved that with dual wall pipes, and special clamps with impregnated wiremesh inserts, and underslung mufflers.

              For you, I recommend ;
              burning out the exhaust baffle
              a headerwrap on the frontmost vertical section,
              RTV sealer on the joints
              and set the idle-speed higher.

              The idea here is to keep the exhaust hot enough so the water vapor exits the system, instead of condensing and running back into the low parts. After the muffler fills up with water, it has no place to go but downhill, unless
              you blast it out by reving it up, or
              drill an exit hole, braze in a spigot, and rout the near boiling water away with a silicon hose.
               
              Last edited: Sep 29, 2020
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              • famous bob

                famous bob mopar misfit

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                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^agree
                But all 2 strokes will usually foul a silencer/muffler, and need to be cleaned . I just haqd to do it on my leaf blower , and had to do it on my old quadzillas.
                 
              • mbaird

                mbaird mbaird

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                Your getting drool... 24:1 seems way too much . But if that is recomended .... try a good synthetic oil like Motul and mix 40:1 .
                The reson your plugs look good at 24:1 is because the oil is displacing the fuel and actually leaning out the A/F . But the oil is not burning and running out the pipe .
                 
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                • AJ/FormS

                  AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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                  That's right;
                  some of the oil, maybe most, goes out the pipe with the hot exhaust. But some condenses in the system and eventually plugs the spark arrestor, if equipped, and or the baffle.
                  In the past we removed the tuned pipe poured diesel into them, stood them up, and set them on fire. Later, we retrieved them, cleaned the outside, hit 'em with Hi-temp paint, and re-installed them;
                  instant tune-up.
                   
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                  • yellow rose

                    yellow rose Overnight Sensation FABO Gold Member

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                    THIS^^^^^^^

                    And when you get rid of all that oil, it will be fuel rich and you’ll need to do some jetting so it won’t foul plugs.
                     
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                    • George Jets

                      George Jets 1967 Dart 2 Door FABO Gold Member

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                      Yes, I run 50:1 in all of my 2 cycle chainsaws, never ever came remotely close to scoring a piston or burning a hole in top of one.

                      They run so much better on non Ethanol fuel too. Start way easier and run way better and more power.

                      The Ethanol fuel draws moisture just sitting in the tank and when you have the gas cap off, and in your gas cans too. Hence the moisture condensing back out dripping out of your cold exhaust pipe.
                       
                    • krazykuda

                      krazykuda Well-Known Member FABO Gold Member How-To Section Editor

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                    • mbaird

                      mbaird mbaird

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                      2F8A1939-6F24-4305-9F17-DE6DD64A2825.jpeg
                      I run Motorex 2t Synthetic in that KTM ( notsure if you can see it on trailer) @ 50:1...
                      Forgot I had already mixed my oil on last tank and added more. Smoked like a banshee and drooled ! Didnt foul a plug though .
                       
                    • ike61

                      ike61 Well-Known Member

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                      Maybe they recommend 24:1 so kids didnt blow them up so easily??
                       
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