Engine Trouble Skyhawk 66cc suddenly running poorly

Discussion in '2-Stroke Engines' started by Nightdrv, Oct 25, 2012.

  1. Nightdrv

    Nightdrv New Member

    I've put 62 miles on this motor. Proper run-in procedures, upgraded fuel line, spark plug wire, plug boot, and plug were all installed while new. Motor has run like a top ever since Day 1. However, the bike had to be put in storage for a few weeks. After pulling it out and getting it going, it's been fine every day for 4 days straight. Until today. Ran this morning, a little rough.. but useable. Later this afternoon, nothing. Only starts if I pedal up to high speed and drop clutch, and play with the throttle. But not only that, it's sputtering horribly. It's as if it's starving for something, be it fuel or electricity I don't know. I pulled the plug and cleaned it to brand new state. Checked plug wire and boot, both perfect. Tightened all screw and bolts that could've needed tightening, and all were perfect. Pulled air filter off and checked for the throttle (whatever it's called) to move freely. It's perfect. Pulled cylinder head off, all is perfect inside. Pulled muffler off, gasket is not great, but more than good enough to run. Pulled cap off of muffler, no clogging that I can see. Opened drain screw on carb, fuel drips freely. Tried playing with choke and idle adjust screw, both make no difference while running. Motor cannot idle at all. It simply dies.

    Anyone help?

  2. crassius

    crassius Well-Known Member

    if you're getting a lot of exhaust smoke, it could be that your bottom end is full of fuel - keeping it running for a while should clear it out

    what it really sounds like though, is a leaking head gasket - completely clean the area between the head & cylinder, then look for oil residue showing up there (you may need to add a couple washers under each head nut to get it to seat again)
  3. Nightdrv

    Nightdrv New Member

    There has always been a lot of smoke while idling... everybody told me (here locally) that it was normal during break in. As for the head gasket, I admit there WAS a tiny bit of residue around one area. It came with a metal gasket that's super thin. I also got a spare head gasket, and two spare exhaust gaskets with the kit. I will install both on the next warm day and report back.
    Last edited: Oct 26, 2012
  4. crassius

    crassius Well-Known Member

    NOTE: the acorn nuts on the head bolts will sometimes bottom out before the head is tight - to fix this, you need to add some washers under them or just break the tops off the nuts so they go down all the way - you want to press a sharp ridge all the way around the gasket when the head seats onto it
  5. Nightdrv

    Nightdrv New Member


    Pulled the head gasket and exhaust gasket off, cleaned and replaced with new ones. Test rode for 2 minutes, and it did maybe 5% better. Came back and pulled the fuel line off to check for obstructions - nothing. Pulled carb off and checked all over - nothing. O-ring btw was still perfect. Also pulled bowl off bottom of carb, everything perfect, no residue anywhere and all parts move freely. Pulled fuel jet out and checked for blockage - nothing. Reassembled everything, checked tightness of all possible bolts/nuts/wires, and went for a ride. It works!! Not 100%, but very close! It still bogs down a bit at low rpm, but mid and high are perfect again! And it idles! I don't know what I did, but it runs!

    Note: Mine came with standard nuts, not acorns... so it hasn't been a concern.

    Now question #2: Why does my 6v headlight not light up almost at all? (wired correctly) If the ground isn't good enough, could the brightness be affected in that way?
    Last edited: Oct 27, 2012
  6. crassius

    crassius Well-Known Member

    OOPS! Sounds like you connected the white wire to a headlight. As you might see in some installation instructions, this wire can also be used to kill the engine by hooking it to the kill switch. Hooked to a light, it will almost always give a weak ignition.

    Everyone just cuts that wire off on these kits.
  7. Nightdrv

    Nightdrv New Member

    Latest update:

    Disconnected headlight out of curiosity.... and boom! It runs beautifully! Now I just want to know how some people have the ability to run lights, while others don't?
  8. Al.Fisherman

    Al.Fisherman Active Member

    In order to run a headlight the WATTS need to be low. conventional bulbs draw too many WATTS. LED's can work nice. I used a battery operated light.
  9. jeffuehrer

    jeffuehrer Member

    I don't even bother connecting a light to the engine based on all the problems I've heard not to mention I want to use a headlamp that emits 900 lumens. There are some nice headlamps out there that are easy to mount and are more powerful than anything that can be used connected to the motor. If you don't need to see with your light than connect it to the motor.
  10. Luthierpro

    Luthierpro Guest