what do i do my engine my engine died while driving?

Discussion in 'Electrical' started by determined, Apr 27, 2014.

  1. determined

    determined Member

    My engine had less than twenty miles on it when it died as i was cruising around the block at about half throttle .i checked all the connections and they look good but it wont start now .im convinced its not getting spark but dont know what do do first to fix it. Also it got rained on slightly but still ran good after that .i did notice gas on the spark plug seeping through the porcelin .but thats never been a problem before .can someone advise me where to start? Im new to this hobby.

  2. ua2pants

    ua2pants Member

    I actually just had this problem today as well. The steps I took to figure out what the culprit was are as follows.

    Check to see if a different plug will start the engine.
    Try a different plug cable and boot.
    Test your CDI with a multi-meter (Red probe to blue wire, Black probe to Black) and you should get roughly 350 +/- 50 Ohms of resistance).
    Test your stator coil with multi-meter (Red to Blue, Black to black) and you should get roughly 7-8 Ohms.
    If all of that has been done and checks out, It's possible that your magneto may be weak, or that it has "jumped" and rotated on the shaft.
    That would cause the timing to be way off and would spark at the bottom of TDC (top dead center, or when the piston is at its highest point).

    Check all of these things and then get back to me.

    If all of that is good, check for leaks (head gasket, base gasket, case gasket, etc.)

    What color is your plug?

    Clog in the carb? (i know you said there is gas coming from around the plug but it may not be enough to fire)
  3. ua2pants

    ua2pants Member

    Forgot to mention, make sure that if you're using your white wire from the coil, that it isn't using to much power as it can cause extreme theft of spark.
    If you aren't using the white wire, make sure it isn't touching any metal part of the bike, as it will cause a short like pushing the kill switch.

    If you have your kill switch hooked up, push the button a few times as these switches are known to sometimes stick.

    Try disconnecting your kill switch entirely, if the bike starts, to shut it off, just stall the motor from a dead stop. (just release the clutch).
  4. determined

    determined Member

    great info ! I sure do appreciate all the direction ill get busy as soon as possible and get back to ya
  5. determined

    determined Member

    well I tested like you said and got nothing on the magneto wires and nothing on the cdi. hopefully I am using my new mm right I set it on ohms and have then plugged into the proper ports but the only way I got any kind of reading is when I touched both red and black probes to a single wire what do I do next?
  6. ua2pants

    ua2pants Member

    Okay, you want to make sure the settings on your mm are set to ohms without a "K" next to it, as that would be set to thousands of ohms. Once it's set correctly, you can hook the red up to blue, and black to black. If you aren't getting a reading then the coil is shot and needs replaced unfortunately.

    Make sure that the black wire coming from the engine (where it is screwed in to the coil) didn't come loose. See if you can tighten it and check again. If you still aren't getting a reading, it's burnt out.

    P.s.-you don't have to pedal the bike or anything, just touch the leads to the wires.

    The good news is that you can get a replacement pretty cheap!!

    I'm in the same boat as you, I need to replace my coil although it's not even 2 months old.

    What I've come to realize is the spark plug gap has a lot to do with these cheap coils burning up. The larger the gap, the harder the coils has to work to make a strong enough spark to jump it.

    For future reference, I ruin my gap at .015 and it ran great, but I think my coil was defective (cheaply made, poor QC)

    Best of luck though!!!
  7. determined

    determined Member

    Thank you for the help .can you tell me a good source for cdi's and magneto's? And one more quick question. Do you mean i should set my gap at .015 or that .015 ruined yours im a little confused on the proper gap but what you said about the gap being to big made a lot of sense because i set it pretty big prior to the dead everything .i also was ridding it pretty fast justbprior to it dying on me
  8. ua2pants

    ua2pants Member

    It's not a problem. We all start as a beginner.

    As for a good place for everything, if you want the generic stuff, eBay is a great source. I wouldn't get a cdi just yet, as I'm sure it's still good. However, the stock cdi that comes with the kit don't last very long either, so it wouldn't hurt to have a spare. You can get the jaguar cdi, but I can't testify for it, as I've never used one, but the statistics do work out.

    Now, as for the spark.

    There's a lot to determine on what the gap should be. A lot is trial and error. Sorry for any confusion as well. If the spark gap is to small, then there is the possibility of an over charge going back to your cdi, which can fry it. I'd say anywhere between .015 and .030 max should be the perfect distance. Also, the numbers on disk plugs mean a lot too. Like the NGK b6hs plug is ideal. The smaller the number, the cooler the spark, which means your engine will run cooler, in turn, longer engine life.

    So to recap, eBay for generic coils, the magneto is the magnet on the shaft, those rarely go bad on such a new engine.

    Your CDI should be fine, but it's a good idea to keep a spare to save yourself time if/when that one goes out.

    Plug gap, I'd say a safe bet would be .025.

    Hope all of this helped!! If you Galen to locate a aftermarket coil, please post where you found it, as I have yet to locate one!

    Have a great night!!
    determined likes this.
  9. ua2pants

    ua2pants Member

    I hate autocorrect haha and I'm tired. I didn't mean "disk plugs".
    Meant to say spark plugs.

    And not Galen, I meant locate haha.
  10. butre

    butre Well-Known Member

    I use approximately a .035 plug gap. Longer gap makes for a better spark if the ignition can handle it but longer spark gaps kill the ignition system faster and if it's too long the ignition won't be able to spark the gap.

    I use a Champion L82C plug with good results.
    determined likes this.
  11. determined

    determined Member

    Wow what great info .thank you for clarifying all that for me . Im glad i did buy the ngk b6hs .im going to check out ebay for parts as soon as i can . But im also thinking that if my cdi is good wouldnt i get some kind of resistence with my mm.?
  12. determined

    determined Member

    Oh ok no problem .and i wish you a good night as well
  13. determined

    determined Member

    When you say a bigger gap will kill the ignition do you mean the cdi or the coil?
  14. ua2pants

    ua2pants Member

    Sorry for taking so long, but to answer your first question. As far as I know, there shouldn't be any resistance with the CDI unit. I have to check mine to confirm however.

    Once I check mine, i'll get back to you and let you know.

    In the mean time, the only other test I can think of, is to hook up your MM to the coil (not cdi) wires, blue/Red and black/Black. Set your MM to read AC voltage and push your bike.
    You should get between 30-50 AC volts.
    If you do not get the above voltage with the MM set to read AC, then your coil is shot.

    If it does read that however, then the coil is fine. If the coil is good, check the resistance of the spark plug wire. You want extremely low resistance (ohms) on it.

    Is it still the stock plug wire? If so, check inside the cap to make sure its making a solid connection to the plug itself. The stock plug caps are junk.

    Again, i'll check my cdi and get back to you!
  15. determined

    determined Member

    Thanx for the info .i get zero resistence with my cdi but a get a little with the spark plug wire .i get barely any resistence with the blue and white wire comming from coil but nothing on the coil when i test with the ground and blue or white .i only get a reading on ohms on the coil when i test the blue and white at yhe same time. Im pretty sure i should just replace both coil and cdi .i can both on ebay for around 20 bucks but i hate for it to happen again so im considering a better cdi .got any recommendatipns on quality parts? Or can i get by awhile on the cheap stuff.? Oh yea i tried what u suggested with pushing the bike and got nothing on volts
  16. ua2pants

    ua2pants Member

    I can confirm that you will not get any resistance from the CDI alone in any configuration. If you do not get a reading when touching black to ground from the coil and red to either blue or white, that does confirm that your coil is burnt.

    If you want to spend the money and get both the coil and CDI, it is a good investment as sooner or later, the CDI will burn up.

    As for an aftermarket CDI, the only one that I can think of would be the jaguar cdi.


    Above is a link to the forum member Jaguar's website. I highly recommend you check it out for lots of useful information, as well as if you want to spend the money, get his upgraded CDI.


    Above is a link to the products that Jaguar has for sale. His CDI runs at $75 without shipping, so again, proceed at your own expense!!

    Hopefully i'll be able to locate an aftermarket magneto coil, as these ones are bare bones and junk to begin with.

    Let me know what you decide to do!
  17. KCvale

    KCvale Motorized Bicycle Vendor

    Missinfrmation once is one, twice means let's clear things up to track an electrical problem on a 2-stroke.

    Disconnect the wires between the magneto (the part in the engine) and the CDI (black box with the plug wire outside)

    Note which color wire probe wires you use here don't matter.

    Put a probe on your black engines magneto wire and the other against a head nut.
    It should a read a dead short just as if you touched the probes together, that is called a continuity test.

    If you get a total open (infinite resistance) then pull off the front left cover to get to the actual magneto leads themselves.
    The blue wire is the upper connection.
    Just above it is a tab that solders to the big magnet part the magneto sits in.

    Put your ohm meter to the black magneto output wire and a head bolt.
    It should read a dead short (near 0 ohms) as that is spark plug ground.

    Chances are that little tab soldered at the top is no longer attached to the motor base so just re-solder on until you have a dead solild connection between your black wire and the head.

    On the off chance that is not it you can check the magneto by ohming between the magneto and lug and the head, probe the blue wire to the head, around 325 ohms is good as it's just a coil of wire.
    If it reads a dead short or totally open you have a bad coil.

    If all that checks then you are to the CDI.
    This you will need to pay attention to polarity to check.

    Set your meter 20 20K range or thereabouts depending on your meter.
    Put the red meter probe on the CDI's black ground wire.
    Stick the meters black - lead into you spark plug cap.
    You should get around 6.9K ohms give or take 500 oms.

    Chances are if you went this far and it's an open it's the plug wire or cap.
    It's tough but you unscrew via pliers the spark plug wire from the the CDI base, you need to get to get to the little wood screw in the cdi the wire screws on to.

    Now ohm the actual CDI 'wood screw' output with a - black probe with the red + meter proble hooked to a the CDI's black output wire.
    Again, around 6.9K ohms means it's good and just had a bad plug wire or cap.


    Hopefully that will get you running again without just randomly buying new parts to try as it's just not that hard to find where it's failing.