66cc skyhawk with cns carb bogging out

Discussion in '2-Stroke Engines' started by drebinpk, Oct 5, 2010.

  1. drebinpk

    drebinpk New Member

    so ive had by motorized bike for a couple weeks now and it just doesnt seam to run the way it should. when im riding i hesitates before exelerating and once i get too about 25mph it just sounds like its either bogging down or missing or something it just plain doesnt run smooth but if i go on a down hill it will smooth out all the way too 30mph keep in mind im only about 140lbs so i would think it should go 30 on flats right? and it should still run right not bogging down even at that?
     

  2. drebinpk

    drebinpk New Member

    oh i forgot to mention when i have the clutch in and give it close to full throttle it will wind up but then about 2 sec later it will die down for a sec or two with out me letting off the throttle its like its starving for gas every little bit or something
     
  3. motorpsycho

    motorpsycho Active Member

    sounds like your air-fuel mixture is too lean.
    you may have to richen it up by going with a bigger main jet.

    you can try to move the clip on the jet needle (move it downt o richen, up to lean) but this is usually only affective from idle to about 3/4 throttle. at w.o.t. the jet needle doesn't help the mixture, this is where a main jet change usually fixes the problem.
    when you get a bog at w.o.t. it usually indicates that it's running too lean.
     
    Last edited: Oct 5, 2010
  4. drebinpk

    drebinpk New Member

    oh ya one last thing when i get back from a longer ride my muffler smokes for a min or 2
     
  5. motorpsycho

    motorpsycho Active Member

    it sounds like it's too lean. if it is too lean it will run hotter than it should.
    is the muffler smoking on the outer case, or is the smoke coming from inside the muffler?
    if it's coming from the outer case, chances are that it's running too lean. sounds like the muffler is getting way too hot...is it chrome or painted?
     
  6. drebinpk

    drebinpk New Member

    its comming from the outside of muffler and its painted flat black
     
  7. motorpsycho

    motorpsycho Active Member

    since the muffler is painted flat black (i am assuming that it's still fairly new?) the smoke could be the paint burning off because it's running too hot....too lean.
    they do not use the best high temp paint. on these mufflers (or did you paint it yourself?)
    even high temp paint will burn off somewhat eventually.
    i still think it's running too lean because of the bog you are getting.
    this is just a guess, i could be wrong.
     
  8. drebinpk

    drebinpk New Member

    how would i go about richening the system?
     
  9. drebinpk

    drebinpk New Member

    well someone told me to get it warmed up and run it full out and just put the choke slightly on and if it ran better my bike in lean if it got worse than its either right or rich and and it got worse even just with one little click on the choke so what does that mean too you?
     
  10. drebinpk

    drebinpk New Member

    oh i turned the air skrew all the way in just now and its running allot better but still boggs out at like the top 1/6 too 1/8 throttle just not as bad and not constantly
     
  11. drebinpk

    drebinpk New Member

    and no smoke came from the muffler even after a 5mile ride
     
  12. motorpsycho

    motorpsycho Active Member

    if this is a cns carb and not an n-t carb, you can play with the air-fuel screw.
    you can change the main jet, but you will have to find jets that fit, and you will need to know what size jet is in the carb. now so you can order bigger jets to experiment with.
    I am not an expert on this, this is just my opinion.
     
  13. WhizBangAndy

    WhizBangAndy Member

    Arent the black exhaust pipes the catalytic version? The lil cat inside would be getting really hot so how does the spark plug look? If its white or light tan then its too lean and you need to unscrew the top of the carb (where the throttle cable goes in) and go one notch down with the c clip on the needle. If that doesen't help then its a fuel feed problem (probably caused by the crappy valve on the tank)
     
  14. motorpsycho

    motorpsycho Active Member

    all happy times kit supplied mufflers (chrome and black) have cats in them. you can easily remove them for better flow.
    if the spark plug is tan, your mixture is pretty much dead on, if it's white or silvery, it's too lean. black it's too rich.(i'm talking air-fuel mixture, not fuel-oil mixture)
    moving the clip on the needle will not do anything for the mixture at wide open throttle.(which is when he is experiencing the bog i think) at wide open throttle, the needle is out of the picture and fuel is being sucked into the engine from the unobstructed jet hole. from idle to about 3/4 throttle, the needle is still in play and is helping meter the fuel that is being sucked through the main jet.
     
  15. drebinpk

    drebinpk New Member

    yes its a cns carb and a cat muffler. if i have time i will check the plug later today and let you guys know what i looks like
     
  16. HeadSmess

    HeadSmess Well-Known Member

    Last edited: Oct 9, 2010
  17. HeadSmess

    HeadSmess Well-Known Member

    its also interesting to note... my new mikuni vm 18, while not tuned in yet, is almost spot on.

    its also changed my plug colour drastically.

    stock carb i had leaned out to a 0.6 main jet....and my plug remained dark. not black, just dark.

    this one? the plug has now gone light tan. same plug. original plug of 4500km and counting... after 50 km its now spotless...

    all i can think of is that this carb atomizes the fuel a lot better than the stock ? droplets of fuel landing on plugs tend to make em black...
     
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