Carby Too lean too rich what to do??

Discussion in '2-Stroke Engines' started by, May 29, 2012.

  1. New Member

    Hey every one i just finished my first build and am having a hard time getting it dialed in. Ive read alot of others advice and ideas and things they've done. I have the CNS V3 carb and have several different size jets i've been playing with. I hooked the two vent hoses together and punched a really small hole in the one hose. I lowered the float for less gas and put a 66 jet in. I got in to the factory sealed air/fuel mixture screw and it was all the way closed so i opened it one full turn and am trying different settings. No matter what i do it either is too lean or too rich. I have almost no power at the low end and it gradually slowly will get up to speed. once there it runs great. Even when its hot and i turn it off for a minute to go in to 7 - 11 it still bogs on take off and i have to use the choke to get it up to cruising speed. I'm running out of ideas has any one had similar problems and figured it out??
    Last edited by a moderator: May 31, 2012

  2. mbatl

    mbatl Member

    That's an adjustable carb right? If so, I would take it to a small engines/weedeater repair shop and see if they can play with the carb.

    I wouldn't dare take the regular china ht carb to anyone, I can only imagine the laughter and entertainment that would happen from people used to working on adjustable quality carbs and then to see the basic ht carb...

    Also, make sure to make one adjustment then test each adjustment before trying another setup.
  3. motorpsycho

    motorpsycho Active Member

    lowering the float will not give you less gas.
    all that does is lower the volume of gas that's in the float bowl, and it will empty sooner.
    the only way a float will give you more gas is if it;s adjusted too high, which will allow the carb to flood over.
    why did you hook the 2 vent tubes together?
    they are meant to just hang and both stay open.
    if the vent tubes are restricted, it will cause a vacuum in the float bowl.
    Kind of like pouring water out of a bleach will slosh and gurgle.

    If you are having to use the choke to get it up to speed on that carb, then it's too lean.
    the choke on the cns carb works different than the choke on an nt carb.
    the choke on an nt, restricts air flow, while the choke on the cns adds more fuel.
    the cns carbs are very diffilcult to get tuned right.
    the nt is simpler, and more reliable, and they are tuneable.
    punch a hole in the bottle to let air in and the flow out of the bottle will be much smoother. i understand that you punched a hole in one of the hoses, but that may be more restrictive than if the hoses are hanging open.
  4. New Member

    Too rich Too lean?

    Thanks for your reply as too the vent hoses i just have been trying what other people have tried that i've read about. And that seemed to help a little bit. I understand that closing those two hoses off creates a vacuum in the bowl thus harder to deliver the fuel but it helped. I'm finding out that there are a lot of vacuum leaks associated with this cns carb. I thinkl i have iot pretty close now instead of going smaller on every thing i've been going larger and it seems to be working. I've got the gap at .032 air/fuel mixture screw out 2 turns and carb piston pin down one notch. By the way i had to make my own notch with a file cause there aren't any on this carb. Can you tell me how far apart the notches are mines about 3/16 from the top of pin. Thanks for your input and help. Zuide
  5. motorpsycho

    motorpsycho Active Member

    I have no idea exactly how far apart the notches are or should be.
    That's a good idea tho, making a notch in the needle with a file.
    i owned one cns carb and i could never get it to run right no matter what i did (yes, i re-jetted it).
    it never made my engine run good at all.
    I went back to the old simple nt carb and have not had any problems with it.
    I did re-jet my nt carb to make it run right.
    I actually had to richen the air-ful mix by going from a .70 jet to a .72.
  6. Mitch135

    Mitch135 New Member

  7. New Member

    thanks Mitch135 I think i'll take your advice and just get an nt carb. For all the time and effort with little results i've spent on this cns i'm ready to throw it across the street. Thanks for the advice. And the price of the nt isn't bad either. Thanks Zuide
  8. Mitch135

    Mitch135 New Member

    I know I already had a regular nt carb but I went to that ebay store for a magneto and CDI and had to buy the speed carb too just cause it was so cheap. And it was definitely worth it. And I'm glad I could help.