Engine Trouble Died on me

Discussion in '2-Stroke Engines' started by cromartie, Aug 3, 2011.

  1. cromartie

    cromartie New Member

    I've been using my motorbike to commute to work on sunny days the last few weeks. It is 17 miles each way and I have over 500 miles on the engine. It has been purring like a kitten -- in fact I just installed the Manic Mechanic hub adapter last night and cruised into work today at 30 mph.

    On the way home, it was purring like a kitten as usual and when I got about 6 miles from home, it died on me out of nowhere. I thought, **** out of gas. Look in the tank and it's a quarter full!!!

    Tried to start it again, no luck. Changed the spark plug to my spare, no luck. Disconnected the kill switch, no luck.

    Commenced to pedal home. :sweatdrop:

    After a few miles, tried to start it again. It fired up slightly, went 30-40 feet and died again.

    Finished pedaling home. :shout:

    What the heck is going on?

  2. Al.Fisherman

    Al.Fisherman Active Member

    Since it was running fine, I'd start with the coil and CDI. Pull the fuel bowl drain out and see if it is actually getting fuel.
  3. cromartie

    cromartie New Member

    Was just outside tinkering with it. Two plugs; no spark on either when out of the cylinder. What's the more likely culprit? The CDI or the magneto? Trying to not spend a ton of money on parts that aren't broken, lol.

    Is it common for these to just quit working mid-drive? Like I said, I got an instant of spark after it died, but that only lasted 30-40 feet.
  4. srdavo

    srdavo Active Member

    ya know.... I had one acted just like that.

    It was a leaky crank seal on the mag side. The mag got oil soaked.

    Just a thought.
  5. cromartie

    cromartie New Member

    Just did some multimeter testing.


    All in ohms:

    Black to white: Infinite
    Blue to white: 339


    Pos/Blue, Neg/Black: Infinite
    Pos/Black, Neg/Blue: Infinite
    Pos/Spark Plug Lead, Neg/Blue: Infinite

    Looks like both are bad?? How is that possible? Like I said it was purring along then dead.

    And if that is the case, where can I purchase a new magneto and CDI that won't go poof in 500 miles?

    By the way, here's a pic of the Magneto housing. Anything look out of the ordinary to you guys or not?

  6. Al.Fisherman

    Al.Fisherman Active Member

    Color can be deceiving, but the coil looks like toast (see in picture below). But get rid of the white wire, cut it off. That's what is nice about electronics most of the time....when it wants to die it goes dead. The most aggravating thing is for something to go out periodically. The old coils on engines gave problems at times when they got hot, cool down and would work. But then again, you might be too young to remember that.

    Is it common for these to just quit working mid-drive? Like I said, I got an instant of spark after it died, but that only lasted 30-40 feet. My very first engine had a coil problem...three days of riding and that was it. Since I didn't have the values (before I joined either forum), I deducted that it was the coil or CDI, but didn't know which one (I made a timing light). At that time they were $10.00 each so I bought one of each..it was the coil, CDI was fine..Now I have a spare. Through out life I've come to the philosophy, that if you have a extra part, that part won't go bad. Five builds (since 3/2009), and nare a bad coil or CDI.
    Last edited: Aug 3, 2011
  7. cromartie

    cromartie New Member

    What would cause a perfectly good working coil to just go bad?
  8. Al.Fisherman

    Al.Fisherman Active Member

    The windings are super thin...Cheap Chinese ****. What do you expect, a $50.00 coil in a $150.00 engine??
    Last edited: Aug 3, 2011
  9. srdavo

    srdavo Active Member

    Is there a gap at the bottom of your magnet? or is it just the angle of the picture?
  10. cromartie

    cromartie New Member

    Gap where? It looks normal to me.
  11. HeadSmess

    HeadSmess Well-Known Member

    clearance... the angle of the photo makes the bottom of the rotor look like its touching the magneto arm...

    your magneto has fried. simple.

    the blue wire is one end of a coil. the white wire is the end of a coil. the other ends of both coils are joined, and are soldered to the magnetos laminated core. that lil blob of solder with the single fine wire at the top. this point is then earth. you could remove the black wire and use any other point of the engine as earth as well. its all one big conductor :)

    and as al says...remove the white wire when you get the new one. do NOT use it as a kill switch. guesses are that you did, just like the manual says :D

    blue to black....theres no diodes, so it wouldnt matter which side you hooked the + of your meter to. infinite is open circuit is fried.

    theres absolutely no connection between the spark plug lead and the blue wire coming from the coil. so theres no reading there either. the black is earth. you should get something from coil lead to black.

    also set the killswitch to earth the blue wire. merely "breaking" the blue wire can cause arcing and subsequent magneto frying as huge unquenched back-emf currents have a party...
    Last edited: Aug 5, 2011
  12. srdavo

    srdavo Active Member

    what he said :D
  13. Big Red

    Big Red Active Member


    $50.00? more like 50 cents.(0r two yen?) Darn those chinese engine factory's
  14. cromartie

    cromartie New Member

    So you are saying hook the kill switch to the blue wire when I get the new magneto installed?
  15. HeadSmess

    HeadSmess Well-Known Member

    yep :) blue and black for the killswitch. most amazingly simple cdi ive ever played with :D

    the white is a (low power) generator for a (low power) light :)

    not sure how earthing it really works as a killswitch, it does, but in the long run kills the magneto too :)
  16. Al.Fisherman

    Al.Fisherman Active Member

    Do not hook up the kill switch until you install new coil/CDI and get it started.
    There are two wires coming from the kill switch...don't worry about colors. Hook 1 wire to the black wires CDI/coil and the 2 wire to the blue CDI/coil wires.
    Last edited: Aug 6, 2011
  17. blue 48

    blue 48 Member

    how about just changing the kill switch to a toggle switch and use it to break the circuit on the blue wire, thus stopping engine as opposed to shorting the circuit like the origional setup does.
    that way it prolongs the life of the electrics, the factory setup seems like their way of being able to sell spare parts that other wise dont usualy fail
  18. HeadSmess

    HeadSmess Well-Known Member

    cus if you "break" the blue wire, it can arc, and easily delivers a few hundred volts... capable of burning through cheap chinese varnish... doubt me? touch it when its running ;)

    whereas shorting it results in a "quenching" of any EMF. no voltage, no go.

    short the blue wire and just pretend the white doesnt exist :rolleyes7:

    once again als the man. dont bother hookin the killswitch up until it is running again...
  19. cromartie

    cromartie New Member

    Runs again. Replaced CDI and magneto. Fired up in first 5 feet of trying. Amazing stuff I say. Hopefully these components last a little longer than 600 miles.
  20. blue 48

    blue 48 Member

    oh ok i under stand now. im just paranoid about the whole shorting thing although you make a good point about quenching the system can it work on a keyed system as apposed to the factory push button? im a mechanic but i hate hate hate electrical work and try to avoid it at all cost