No power with Skyhawk

Discussion in '2-Stroke Engines' started by Adams77, May 10, 2010.

  1. Adams77

    Adams77 New Member

    I bought two kits, one is the 66cc and the other is a 49cc both are skyhawk kits.

    The 66 runs good and has a nice pull to it, the 49 wont pull at all. In order to keep it running you either keep the clutch in or you must pedal.

    The engine will rev up with no load on it.

    I have swapped the carburetors around and changed the plugs and I get the same situation. What do I do next?

  2. Al.Fisherman

    Al.Fisherman Active Member

    Swap out both the magneto and CDI, check compression, and timing. Although not a problem at the moment, do a hardware upgrade on both.
  3. Adams77

    Adams77 New Member

    any procedures for checking timing?
  4. Al.Fisherman

    Al.Fisherman Active Member

    Timing is determined by the position of the magnet on the crankshaft inside the coil. A key is what keeps the magnet in position on the crankshaft. The way these are built, the only way of checking is to pull the magnet as you can't see the key with the magnet installed, although you can see the grove in the magnet where it slides over the key and into place (under the nut). The position of the key while on the crankshaft and at TDC will be approximately the 1:00 position. The coil usually needs to be removed first, for easier access to the magnet.
  5. Apachekid

    Apachekid Member

    Runnin rough 66cc grubee

    Hi Al!.....Hope you're not to busy today... I got a question for you....If I remove magnet will I be able to tell if key is in place on crankshaft? Also, whats the odds the magnet is not in right position? Im running real rough right now, like out of time, Ive checked all the air leaks, head bolts tight, good plug and wire. Motor smokes more than normal...cant get any power, vibrates sittin on the centerstand.If it was my 340 Mopar, Id twist the distributor and that would be the end of it. Kinda of running out of ideas:sweatdrop:Help!..........Cheers, Apache
  6. Al.Fisherman

    Al.Fisherman Active Member

    These engines are either in time or not. When you pull the magnet, inspect that there is in fact a key (half moon) installed. Do this slowly and the magnet will grab the key and get stuck on the magnet. If the key is in fact in place check to see if it might of got sheared. If it did and the magnet rotated on the crankshaft ever so slightly you will be out of time. I'll take some pictures in a few minutes.

    Picture 1. Correct position of key way at TDC
    Picture 2. Correct magnet placement.
    Picture 3. Incorrect magnet placement

    Attached Files:

    Last edited: May 14, 2010
  7. Apachekid

    Apachekid Member

    Thanks Al, I appreciate it very much. Now I can see where I am! Excellent pictures....
  8. Hajuu

    Hajuu Member

    "The engine will rev up with no load on it. "

    If you mean its revving with the clutch in, it's probably the idle speed screw. If its revving with the clutch out and no accellerator, it's probably that the needle or cable is sticking in the carb.

    Not sure what itd have to do with the cdi/magneto :/
  9. KCvale

    KCvale Motorized Bicycle Vendor

    Ya, thanks Al.
    My 66 runs good up to about 22 and then starts running kind of crappy, missing, vibrating, and acting like it's not getting the proper fuel/air all the same time.

    I am going to start with all the basic today like plug, leaks, air filter. gas line, etc, but it's nice to have your pics about timing handy here.
    I guess there is no timing mark on the motor so you could use a timing light?
    That would sure be handy.
  10. Apachekid

    Apachekid Member

  11. Al.Fisherman

    Al.Fisherman Active Member

    It's impossible to slide both the magnet and key on at the same time. The key needs to be in place first then the magnet slid on. Here is a trick........super glue key into place on crankshaft, let dry and install magnet. This way the magnet won't grab the key and pull it out of place while installing. Curved portion of key sets into the crankshaft grove.
    Last edited: May 19, 2010
  12. Apachekid

    Apachekid Member

    Thanks again, Al. Im gonna vote for ya
  13. Al.Fisherman

    Al.Fisherman Active Member

    Keep paying attention, this ole dog can teach some tricks... :)
  14. 577-Jersey

    577-Jersey New Member

    I know its an old thread,,
    But this does not sound like a timing issue,,more like a fuel cap not venting properly,,if it rev's smooth without a load but no power under load,,its a fuel problem,,I wouldnt rule out coil or air leak either :)
  15. V 35

    V 35 Member

    I'm wondering if the problem is mechanical , and not the engine . Best test I can think of is ... Remove plug [ no compression ]
    Pedal bike around with clutch in, release clutch, and check for drag. If hard to pedal = chain too tight If it pedals OK with clutch
    in, but pedals hard when released, clutch bearing might be bad, or flower nut way too tight. Since you have 2 bikes, a spare carb isn't a bad idea. I like the old SPEED brand carbs, cheap and simple. The mag / coil swap is easy enough, but possibly not the problem.

    My first build had no torque until the motor broke in, after a couple tanks of gas, torque increased dramatically, and the clutch became much easier to use.
  16. 577-Jersey

    577-Jersey New Member

    Great info here guys,,
    Im really enjoying myself!!
  17. Big Red

    Big Red Active Member

  18. KCvale

    KCvale Motorized Bicycle Vendor