Engine bogging and backfiring..

Discussion in '2-Stroke Engines' started by agrmodz, Jul 28, 2016.

  1. agrmodz

    agrmodz Member

    it only started to happen today, the motor is going extremely slow.. (10km) and is bogging. then it back fires, i pulled the clutch in after the backfire and the engine cut out and it just keeps doing the same thing...
    Earlier on i thought i heard some tinging noises but i'm not sure.. Any help is appreciated!!
     

  2. crassius

    crassius Well-Known Member

    look around head gasket for oil residue - head may be loose
     
  3. jaguar

    jaguar Well-Known Member

    what mods does the engine have?
     
  4. gary55

    gary55 Active Member

    My guess is a broken ring or serious cylinder damage. Pop the head and have a look.
     
  5. jaguar

    jaguar Well-Known Member

    that would cause power loss, not backfiring
     
  6. jatgm1

    jatgm1 Member

    you check the woodruff key?
     
  7. agrmodz

    agrmodz Member

    Would running it with an air leak in the carby cause it to do this? Too much air to fuel?
     
  8. agrmodz

    agrmodz Member

    none, i did try a racing carby but the jets were wrong and i'm waiting from my jet kit to arrive.. so everything is stock.. i do have a 32t sprocket but thats nothing on the motor..
     
  9. gary55

    gary55 Active Member

    I've seen broken rings cause backfire through the carb.
     
  10. agrmodz

    agrmodz Member

    The pistons and rings look perfect.
     
  11. crassius

    crassius Well-Known Member

    last year there were CDI units that backfired a while before dying - unlikely though

    I'd still be checking for head gasket leaking.
     
  12. agrmodz

    agrmodz Member

    theres no leakage. :( I did take the carb apart because it was running rough and taking FOREVER to get up to speed.... it does eventually get up to speed but takes AGES, it is real hard ot get it to idle as well. it was like that since i got it, every now and again i had to give it a rev to keep it going... I'm thinking its sucking air from the carby bowl because its leaking from there and some of the gasket is popping out...
     
  13. gary55

    gary55 Active Member

    Glad to hear the piston rings and cylinder is good. The backfire is the odd symptom. Jag may have something with the woodruff key. I've just never seen the one on the magnet side go bad. There is really no load there, still worth looking at. air leaks around the carb generally cause high revs that can't be controlled with idle adjustment. was it a backfire through exhaust or a spit through the carb. Is there any fuel in your clutch or magneto covers?
     
  14. agrmodz

    agrmodz Member

    I'll check now
     
  15. agrmodz

    agrmodz Member

    Everything looks perfect, the motor is new so i wouldn't expect anything tobad, is it possible that it is the carby?
     
  16. gary55

    gary55 Active Member

    It is more than likely the shut off needle in the float bowl not sealing. If it is not stopping the fuel from flowing in the fuel runs out of the carb even if the gasket is good. It also fills up your crank case with raw fuel and makes the bike run like crap. Clean the bowl, float needle, and needle housing with carb cleaner. Make sure the float doesn't have a leak. then bend the float tines a little and check if needle is seating all the way. It will take a little while to get all the raw fuel out of the crank case. If you can get the rear wheel off the ground and pedel it with the plug out you will get a lot of it out without fouling the plug. You will probably see fuel coming out of the exhaust. Just curious, the day this all started did you happen to leave the gas on over night?
     
  17. gary55

    gary55 Active Member

    With what you said about the carb leaking I would bet the float needle is the trouble maker. I've seen a lot of brand new carbs leak like pigs. When the raw fuel gets in the crank case it runs like sh*t. If you can't get it to stop leaking through cleaning and float adjustment get a new one and keep the old one for parts.
     
  18. agrmodz

    agrmodz Member

    Should i put my racing carb on? its got the wrong jet but i've bought a jet set from china.. it will run alot slower with it on but i'll have to make use of it until the jets arrive, it that a good idea?
     
  19. agrmodz

    agrmodz Member

    Also when i took the carb apart i did notice the bit that the float pushes up to close the line gets jammed if u give it a nudge...
     
  20. gary55

    gary55 Active Member

    I think that's your best bet right now. Is the racing carb the delorto clone with auto choke release or the cns carb with the separate choke cable. I might be able to give you a starting point for jetting if I know the elevation and average temp. where you live.
     
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