First build done but have a question!

Discussion in 'Introduce Yourself' started by Biz Rigs, Oct 31, 2010.

  1. Biz Rigs

    Biz Rigs New Member

    Joined:
    Sep 20, 2010
    Messages:
    6
    Likes Received:
    0
    I finished my first build last Saturday. I have a 66cc Skyhawk on a Cranbrook bike. Started right up and runs great! I read a lot of posts before starting so I was able to quickly fix problems as they came up.

    I have one problem now. The bike runs great but when I slow down to a stop sign or intersection and pull in the clutch, my engine stops. It will not idle at all, even after warming up and running for 10 minutes on the road. Any suggestions for troubleshooting this issue?

    Thanks!
     
  2. Nougat

    Nougat New Member

    Joined:
    Nov 4, 2009
    Messages:
    1,332
    Likes Received:
    0
    Make sure you're opening the choke - lever on the right side of the carb, should be in the down position. Either that, or the clutch cable is not adjusted properly; it should pedal without turning the engine over with the clutch handle pulled. Lastly, could be the idle is set too low. Rev it up standing still and screw the idle screw in a touch. I'm messing with my idle all the time.

    In any case, it doesn't sound like a big deal. Welcome!
     
  3. Biz Rigs

    Biz Rigs New Member

    Joined:
    Sep 20, 2010
    Messages:
    6
    Likes Received:
    0
    Nougat - I have the high performance CNS carb and there are 2 screws on it. I'm guessing that the one closer to the fuel line is for the idle? There's also one close to the air filter. This kit has the choke shifter that attaches to the bars near the throttle. I'll bet it's an idle problem beacuse my clutch cable and choke seem to be fine.

    Thanks!
     
  4. Nougat

    Nougat New Member

    Joined:
    Nov 4, 2009
    Messages:
    1,332
    Likes Received:
    0
    Okay, the CNS:

    The screw by the air cleaner is the idle air screw. When the engine is idling, it's only pulling fuel through tue pilot jet, and that screw adjusts how much air goes through the pilot circuit. This *only* affects fuel mix at idle, not high in the throttle range.

    The other screw is the idle speed screw. In for higher idle, out for lower idle.

    I've heard that these screws on the carbs that come with the 2010 Grubee kits are Loctited in place. Careful not to strip them, they're kind of soft.

    The other adjustments are just like in the NT: move the needle clip around, rejet the main jet (I'm not sure what the stock size is). I've also heard that putting the throttle needle from the NT carb in the CNS might help with throttle response, because it has a different taper.

    But your problem is with idling. You don't mention what fuel mix you're using. 24:1 for break-in, and 32:1 after that, unless you're going to use synthetic, in which case you'll need to follow the guidelines from the oil manufacturer. Many of the instructions say 16:1, which is just plain wrong, and could cause the condition you describe.
     
  5. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

    Joined:
    Jan 8, 2008
    Messages:
    11,529
    Likes Received:
    4
    Great info!
     
  6. Biz Rigs

    Biz Rigs New Member

    Joined:
    Sep 20, 2010
    Messages:
    6
    Likes Received:
    0
    I agree, great info! I'll check it out tonight.
    It's hard to find info on this carb. I'm at 24:1 fuel mix.

    Thanks again! Here's a pic.
     

    Attached Files:

  7. Nougat

    Nougat New Member

    Joined:
    Nov 4, 2009
    Messages:
    1,332
    Likes Received:
    0
    One of my concerns about the CNS carb is that the Yamaha engines it was used on had oil injection. I know the pilot jet is *extremely* small. I wonder if two-cycle premix fuel would clog the pilot jet more easily. Perhaps not, as I recall reading about people with their PW80s disconnecting the oil injection pump and just using premix without difficulty. Still, that was also on the OEM Mikuni carb with a proper Yamaha engine, not a knockoff carb with an HT motor.

    One last point: the "vacuum" hoses on the carb. I've not seen the CNS carb in person, but I'm looking at the pictures at Spookytooth. I can tell you that the port on the bottom of the float bowl is an overflow. Attach a tube to that, and route that tube away from the motor. Any fuel overflow will drip to the ground. *Don't* hook it up to another port!

    It looks like there are three :confused: ports on the top of the carb; two on the left side pointing up, and one on the right side, pointing at an angle. The right side angled one probably goes to the carb intake. On the Yamahas, I think that was to provide vacuum for a diaphragm-powered fuel petcock. For our machines, it needs to be capped off.

    The other two ports - one of them is a bowl vent. Attach a tube to that and route that tube so it's pointing down, too. This will prevent crap from getting in the carb while still allowing venting. The other port - I have no idea what that's for. It might be the air intake for the idle circuit. On the OEM carbs, that was a separate little hole behind the air cleaner; maybe they changed it for this one.

    I would *love* to see some good pics of this carb, from multiple angles, and disassembled even.
     
  8. Biz Rigs

    Biz Rigs New Member

    Joined:
    Sep 20, 2010
    Messages:
    6
    Likes Received:
    0
    Here's some pics of the carb. There's 2 tubes. One is for overflow and the other appears to be some kind of vaccuum line but I'm not sure.
     

    Attached Files:

  9. Biz Rigs

    Biz Rigs New Member

    Joined:
    Sep 20, 2010
    Messages:
    6
    Likes Received:
    0
    Nougat -
    My idle screw needed to be adjusted. A few turns and it idles nicely. Thanks for your help!


    usflg
     
  10. Nougat

    Nougat New Member

    Joined:
    Nov 4, 2009
    Messages:
    1,332
    Likes Received:
    0
    Okay from what I can see, you have one tube off the bottom of the float bowl, and another tube off the top, on the side by the idle and idle air screws. The float bowl one is overflow, and the top one is bowl vent. Both should be open, and having some tubing on each one - open at the end, and pointing down - is good.
     
  11. Biz Rigs

    Biz Rigs New Member

    Joined:
    Sep 20, 2010
    Messages:
    6
    Likes Received:
    0
    So you are saying I should disconnect the tube at the air filter and leave it hang down? The tube that attaches above the idle screw wraps around the carb and attaches to the filter. It was shipped that way so I did not mess with it. Like I said, there were no directions or diagrams for the carb.

    Thanks!
     
  12. Hammond Egger

    Hammond Egger New Member

    Joined:
    Oct 23, 2010
    Messages:
    270
    Likes Received:
    0
    I'm using Echo PowerblendX at 16:1 to break in a new 2010 66cc Skyhawk. Starts on the first pull, idles fine, runs fine.
     
  13. Nougat

    Nougat New Member

    Joined:
    Nov 4, 2009
    Messages:
    1,332
    Likes Received:
    0
    Ah, wraps around the carb and attaches to the filter - good! That means any air that's getting sucked in is being filtered. That's exactly how it should be.

    I just looked at the pics again - I see where it wraps around, but I couldn't tell from looking the first time that it's hooked up to a port on the intake side of the carb there.
     

Share This Page