Possible CDI issue

Discussion in '2-Stroke Engines' started by jrschultz, May 30, 2014.

  1. jrschultz

    jrschultz New Member

    Hello everyone. I completed my first motored bike, and I am now working out the bugs. I made two rookie mistakes. I went on the bike's first ride, and I got it to start. WooHoo I thought! I took a brief ride down the road, and the throttle broke. Doh! I found out I installed the throttle wrong on the carb side. I had the slide in backwards. In addition to this I didn't have a clean path for the cable. I ended up braking the plastic throttle grip on the handlebars. I'm glad that broke instead of the cable. I've since got a new throttle grip, and I have the throttle operating correctly. It's nice and smooth now. Here's my current issue. While I waited for parts to show up I more cleanly ran my electrical wires. When I hooked everything up again I hooked black to blue on the CDI, thus crossing the wires. I didn't know I did this until after trying to go on a few more rides. I hear the motor turning over, but it obviously didn't fire. I corrected the wiring issue, and now there is no spark. I pulled the plug out, unhooked the kill switch, and spun the rear tire while looking for spark...nothing. Here's my question: Did I blow the CDI by hooking it up backwards? Should I go ahead and replace plug, wire, and CDI?
     

  2. crassius

    crassius Well-Known Member

    first, hold the plug in your hand while turning engine and your hand against the engine to see if you can feel spark - if so, it may be just the plug that's bad

    if no spark, then test the magneto coil for 320 - 360 ohms between blue & black wires, if good, get a CDI, if bad get a coil
     
  3. jrschultz

    jrschultz New Member

    Simple enough. Thank you.
     
  4. jrschultz

    jrschultz New Member

    I bought a new CDI, Spark Plug, and NGK boot. I still don't get a spark. I brought my magneto to work today where there is a multi-meter I used to test across the blue and white wires. I get a little over 500 ohms across the ends of the wires and touching directly to the solder. The resistance is obviously higher than what it is supposed to be. Do these things usually read higher or lower resistance when they go bad?
     
  5. crassius

    crassius Well-Known Member

    testing across the white wire does little as it should never be used - you need to test between blue and ground or black if it is hooked up
     
  6. jrschultz

    jrschultz New Member

    I'm glad you said this. I tested from ground to blue and didn't get a reading. Looking at the coil closely I saw that the thin ground wire was broke from the solder glob. I re-soldered, and now it reads 500 ohms give or take. Thank you for your help and patience. Hopefully now I will get proper spark.
     
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