66cc HT CNS Carburetor Issues

Discussion in '2-Stroke Engines' started by Down_n_Dixie, Sep 23, 2010.

  1. Down_n_Dixie

    Down_n_Dixie New Member

    I'm running a skyhawk 66cc motor with the upgraded performance carburetor. When I pulled the carb out of the box It had an assortment of tubes running across it (pics included). One of the tubes is literaly about an eighth of an inch long, burnt and pinched by whoever boxed it to seal the vent off. When I first Ran the bike it was running Very lean and and bogging down when I opened the choke, and no amount of tuning the idle and air mix screws fixed the problem. I found the culprit, if you look at the pic you can see black tape on the perimeter of the air filter where I covered several holes which seem to have no purpose. Now it runs with the choke open and pulls great but, IT runs EXTREMELY rich, at one point There were flames coming out of the exhaust so I killed it and got off for fear of an explosion lol, but the engine was not overheated so I attribute that to the rich mixture. So after that brief of my situation my QUESTION is, Do these tubes seem correct? And how to correct it if not. Also, is the rich condition the result of not enough airflow due to these tubes? i;ve had no luck leaning it out with the screws and i have the clip set the the second from the top of the needle. ONe last tidbit of info, The engine also does not idle unless I open the throttle slightly. Am currently using 16:1 for the break-in Sorry for the wall of text guys, If any of you make it to the end Any advice would be greatly appreciated. THANKS

    Pic Info: The plug shows the dark and oily rich condition indicator.
    and the carb pic shows the funky tubing on this thing. Sorry
    for the quality I have no macro setting .
     

    Attached Files:


  2. goodtime65

    goodtime65 Member

    They say that the small tube that runs from the top to the bowl on the carb has to be connected, but if you take a real look into it you will see that the fiting on the bowl actualy is an over flow from inside, so that if you carb floods it will not fill your engine. The top of the carb is a vacum so to me this will pull fuel from the bowl causing a rich mixture. Iv'e only been able to get mine running good without the hose
     
  3. HeadSmess

    HeadSmess Well-Known Member

    that tube really does look like it should be two tubes...

    top is the vent/breather for the bowl. you want this hose to stop crud getting in there... but to let air in still.

    the bottom tube is just a drain for the overflow and when you drain the bowl...

    also makes it very easy to check fuel height in the bowl, that hose does :)
     
  4. goodtime65

    goodtime65 Member

    the top hose that you have going to the bottom is a suction. If you look the little brass fitting goes right into the throat, when the air passes by it will create a low pressure causing a vacum. The fuel in the line will be sucked up causing a very rich mixture
     
  5. Down_n_Dixie

    Down_n_Dixie New Member

    Ok, So I should disconnect the long tube, I will try this once I put the carb back on the engine. I ended up taking the carb apart and I found that the float does not fully seal off the gas intake when it is floated as high as it can go. It seems the float was installed upside down.... So I corrected this and it now functions properly, hopefully this will help as well. Also the port that is covered and sealed by the burnt tube seems to be the vent for the air/gas mixture screw, so by being sealed it pretty much makes the screw useless am I right? And why would they seal it off then?? I took that off as well. Now im off to test run my bike, hopefully these adjustments will lean out the mix. Thanks for your help so far and I will post my results when I get back. Oh and maybe that explains why I had no results adjusting the screw in the beginning.
     
    Last edited: Sep 24, 2010
  6. goodtime65

    goodtime65 Member

    The sealed off tube is a vent for the bowl, these 2 should be open. If you remove your air cleaner and look at the front of the carb you will see the idle air inlet on the right. If you look in you will see the needle
     

    Attached Files:

  7. Down_n_Dixie

    Down_n_Dixie New Member

    Goodtime, When I unseal the vent for the bowl my Bike shows all the signs of running too lean, bogging on open throttle and dying when i open the choke. If any of you are currently using one of these carbs effectively could you please post how you have yours set up? (tubes, needle level, mix screw settings, etc.) Also I seem to have noticed a variance in these things, some have a larger airfilter cone and some have smaller ones with holes punched on the bottom perimeter, whats up?
     
  8. skrufryder

    skrufryder Member

    well my carb dosnt have any tubes on it...i was advised by the company I bought it from to remove them....needle is on the lowest setting.....My bike runs much better on a sunny 70's day as apossed to 50 and raining.... The weather here is all over the place in just one day you have to adjust almost every time you ride....
     
  9. HeadSmess

    HeadSmess Well-Known Member

    ahhhh atmospheric tempers.... these engines really do have their moments :p
     
  10. Down_n_Dixie

    Down_n_Dixie New Member

    quick update: So I unplugged the float overflow tube from the top and am letting it hang, also removed the tape so more airflow could come thru and took off the burnt tube as it seemed pointless. No noticeable pwer increase and the mix is still rich even with the clip all the to the leanest setting! Its quite discouraging to be putting around at 15-20 mph tops whle my buddy is zippin around doin 30 on his 50cc and stock carb:shout: I cant seem to figure this out.
    Well I've almost done with my second tank of gas so maybe if I up the mixture to 32:1 it might help out what do you guys think?
     
    Last edited: Sep 25, 2010
  11. skrufryder

    skrufryder Member

  12. montezumasviper

    montezumasviper New Member

    I hate that thing. I've had the exactly same issues as you. One experiment to try is shutting off the fuel while riding, does the engine perform very well soon before it runs out of gas in the bowl?

    Heres what I've found works,

    Unscrew the float, there is a bar that holds the float assembly up. If you have ever tipped the bike on its side this bar comes out of place and prevents the float from stopping fuel flow.

    Use the needle from the original nt carb. This should help a lot. And honestly, don't worry too much about the vents, covering and uncovering them doesn't seem to make a huge difference.

    My bike literally wouldn't run until I did these things and now its the plug is light brown, good luck :)
     
  13. Lazieboy

    Lazieboy Member

  14. Lazieboy

    Lazieboy Member

    Carb or plug ?

    Hey. My 66cc grubee runs good for a block or so then dies like it's out of gas but not. Pull the plug and its wet, so i clean it put it back in and goes for another block and dies again. I have been alternating 2 plugs same story.
    I reciently took carb apart to check jet,put it back togather. so i did it again 2day to double check all looks good. I really need help on this. its like it's getting too much gas or not burning it completely. Whats the dealio.
     
  15. motorpsycho

    motorpsycho Active Member

    you would have to make a round adapter to screw onto the carb. where the stock air filter screws on. then, the rubber peice on the back of that air filter you show, can be clamped around the adaptor.
    I bought a filter off e-bay and it came with a velocity stack / carb. adaptor for a little more money. I could have made an adaptor myself, but it was just easier to just spend a little more $$ and get one that was already made.
    this is similar to the filter i got and it works great. This is not the buyer that i got mine from. you shoudl measure your carb. screw holes to make sure it will fit before you buy it.
    http://cgi.ebay.com/UFO-Chrome-Air-...188?pt=LH_DefaultDomain_0&hash=item35a590f0ec

    you can do a search for "ufo air filter, pocket bike air filter, go ped air filter, scooter air filter" to see if there are other styles and prices.
     
    Last edited: Sep 26, 2010
  16. motorpsycho

    motorpsycho Active Member

    is this the stock carb, that came with your engine?
    if the plug is wet, then you are definitly running way too rich. the float coule be sticking in the down position, causing the carb to flood over. but you said that you took it apart and everything looks good.
    do you have anything hooked to the white wire from the magneto?
    the reason i ask is that if you hook a headlight (or something else) to the white wire, it will steal power gong to the cdi, resulting in a weak spark.
    also, check your wiring connections and make sure no bare wires are touching anything, and look for loose connections.
    you shoudl really get rid of those push together connectors and solder & heatshrink all of your wiring connections.
    your problem could be electrical and not so much the carb, running rich.
    it could be that the spark is weak, from low power going to and coming from the cdi.
     
  17. Lazieboy

    Lazieboy Member

    will check

    Yes stock,nothing hooked to white wire no lights or anythin,I will re check float and ele. connections. I am using 32:1 gas and have for a long time. Wish me luck.
     
  18. Down_n_Dixie

    Down_n_Dixie New Member

    Raining today so I will not be able to tinker with my engine:icon_cry: But I Like the idea about switching the needle out with the nt carb, Just need to find someone who will let me switch em lol. Also I will have to look into the weak spark problem motorpsycho mentioned. So, Since I cannot ride my bike today I decided too look inside the cylinder And when I pulled the head its a nice tan/brown color on the plug side(slant head) and black on the far side. Could this mean my engine is experiencing detonation? Oh, and I have tried the ol shut off the fuel trick and yes, it runs much better with more power and response until it dies.
     
    Last edited: Sep 26, 2010
  19. Lazieboy

    Lazieboy Member

    fixed

    Drained tank and carb, checked all components in carb,reasembeled,filled with new gas, now working. hu
     
  20. motorpsycho

    motorpsycho Active Member

    since you drained the tank AND the carb, the float in the carb. MIGHT have been slightly crooked, allowing the needle & seat to stay open, causing the carb. to flood over.
    you MAY have corrected the problem without even noticing that you did anything when you took the carb, apart.
     
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