No Spark, Replaced everything, At a loss

Discussion in '2-Stroke Engines' started by bluetokamak, May 21, 2015.

  1. bluetokamak

    bluetokamak New Member

    Hi guys. I have browsed some of the forums here regarding similar issues and have yet to find a solution.

    This engine was put together several weeks ago. All of a sudden I couldn't get it to start after I killed it during a break in a ride. I discovered that I am not getting spark.

    I have replaced the spark plug, the magneto, and the cdi. For the new magneto I sanded down the contact areas and removed the white wire. I soldered the magneto leads to the CDI. When testing with an ohm meter, I get a short between engine head and black wire.

    To test for spark, I am walking the bike with the plug body on the engine head bolt (paint is worn away), with clutch engaged. The engine turns over. I also have the kill switch disconnected.

    Any tips on where to go from here? I feel as if I've replaced everything except the magnet...what's going on here?

    Last edited: May 21, 2015

  2. crassius

    crassius Well-Known Member

    you may have a spark that you are not seeing - the only way to be certain there is no spark is to hold plug in hand, with hand against engine

    don't forget to check that plug cap is making good contact with plug too
    Timbone likes this.
  3. jaguar

    jaguar Well-Known Member

  4. bluetokamak

    bluetokamak New Member

    Thanks for the replies, guys. I wound up just replacing the CDI, and that solved the problem. Somehow two CDIs had given up on me in as many weeks, I guess they are pretty low quality. I bought a spare just in case this other one craps out on me. Any reason that two in a row would go bad that I'm overlooking?

  5. crassius

    crassius Well-Known Member

    nope, had it happen here with 2 right out of box dead in 3 or 4 seconds
  6. jaguar

    jaguar Well-Known Member

    stop wasting money on those el crapo CDIs and buy a good aftermarket one that will both improve performance and reliability
  7. battery

    battery Member

    I agree^ best upgrade I made to my engine was the cdi. A huge difference in power and I've had it through the elements for a year and a half so far. Only problem I encountered was ice build-up. Had to tape it up good.
  8. KCvale

    KCvale Motorized Bicycle Vendor

    You are overlooking your engine maybe having a poor magnet.
    The spinning piece hooked to the engine inside the magneto.

    This is my method of trouble shooting an ignition problem that doesn't involve pushing your bike around or shocking yourself for future reference and a way to see if maybe all your other 'bad' parts really are not bad.

    Disconnect everything.

    Ohm the black magneto in the 1-2K range wire to a head bolt, it should read a dead short.
    If not, check the ground tab on the magneto.
    The new skyhawk CDI's have no white wire, ground is the lower connector but it has a wire from it to ground.

    Old style mags with a white wire have a tab out of the mag that solders directly to the mag base and they can come loose, just hold it down and re-solder.

    Ohm the magneto in the 1-2K scale from the black and blue wire, 320-380 ohms is ideal, an open or dead short means a bad magneto.

    Ohm the CDI in the 10K-20K scale.
    Red+ meter probe to CDI black wire.
    Black- meter probe to the spark plug cap.
    You should get about 6.9K ohms +-~500 ohms.

    If not it could be a bad wire or cap.
    Unscrew the plug wire at the cdi, use pliers or even cut it off and dig the junk out if need be and do the same test above again to the cable screw on the CDI.
    If that works get a new wire and plug cap, if not you have a bad CDI.

    If all of that is good there is only one thing left, the magnet.

    That was indeed the problem with this repair on a new build with a 2014 front page engine kit.

    When you pull the 4 bolts out of the magneto mount it should slam itself against the magnet, I mean to the point where it is hard to even get your first bolt in.
    Also note that getting uniform distance between the magneto and magnet is crucial, use a feeler gauge if need be.

    A weak magnet that lets you move the mag around pretty easily is not strong enough to create a spark and swapping out mags and coils won't compensate for a poor magnet as that is where it all starts.