can anybody tell me what the white wire is for?

Discussion in '2-Stroke Engines' started by give me vtec, Jun 11, 2009.

  1. give me vtec

    give me vtec Active Member

    I have a Chinese 80cc and am wondering which wire I need to connect to the white wire... I know it is for the kill switch but which wire do I connect, the black one or the yellow one. I know black is usually the ground but you never know for sure with the chinese. Anything helps... thanks in advance for any comments.

  2. the yellow one.
  3. give me vtec

    give me vtec Active Member

    thanks thats what I thought.
  4. danlandberg

    danlandberg Member

    The white wire is an out put voltage (7 vdc aprox.) I would suggest hooking one wire from kill switch (either color) to the blue or green on the CDI coil, the other wire of the kill switch to chassis ground. either way you do the kill switch in this manner is wrong! It will kill the engine, but it is also hard an the magneto. It is direct power to ground (direct short) The best way, is to use a switch to disconnect power from engine to coil. But for emergancy shut off, both ways above will work.
  5. the right way is white to stripe wire on shutoff. but you can just put the choke on and your engine will turn off,that is if you dont have a airleak.
    i used to have a airleak but i put a o-ring washer in the carb to intake and now no airleak.
  6. danlandberg

    danlandberg Member

    Think again!!! Any direct output power to ground is bad! The white wire will run a head lamp or what ever? That does not draw to much, If your lamp or what ever draws to much it will kill the engine when turned on! Read the way these china made things are wired. No offence but white to kill switch is wrong!!! No matter what!
  7. this comes from the manual:
    Ignition Coil and Engine Kill Switch installation

    A) Mount CD ignition coil on bike frame, close enough to attach coil wire to spark plug. Mount as far away from exhaust pipe as possible to avoid heat damage to semiconductors in CDI module.
    B) Attach CD ignition coil wires to same identical color coded wires coming from engine.
    C) Install Engine Kill Switch: Select one of 3 kinds. A. Small handlebar type: B. Throttle kill switch: C. Kill switch on optional twist handle clutch. Attach chosen kill switch wire to white wire coming from engine. If switch has two wires, take one to frame grd. and one to the engine white wire.
    D) Route all wires away from engine exhaust heat. Secure wires with a plastic tie straps.
    *!WARNING! Operation of engine without stop or kill switch installed could result in personal injury if an emergency stop is required! The only alternate non recommended way of killing the engine is by releasing the clutch lever with bike brakes on and engine at slowest idle.
  8. duivendyk

    duivendyk Guest

    The white wire has a short unsymmetrical ac pulse voltage on it, about plus 6V peak ,to minus 15-20V peak.Consequently it also has a few V neg dc on it.Shorting it to the black wire (engine ground) will reduce the output of the generator coil so much that the plug won't fire,killing the engine.It's an old wife's tale that this can harm the cioil.That's nonsense. I sat down&computed the energy dumped into the shorted portion of the coil if the engine kept on runing at 3k rpm for another 5 sec.It would raise the temp of that part of the coil by less than 10 deg F,which can't possibly harm it
    The blue wire is the coil output,It supplies the energy to the Capacitor Discharge Unit for generating the spark.The blue wire has a LARGE ac voltage on it ,a couple of hunderd volts,more than enough to kill someone if with one hand he held onto the frame and grabbed it with the other.Don't run it all over the bike,it should be connected to the CDI unit and ought not to be used with killl switches as far as I'm concerned.I recommend using a sealed reliable high grade switch for the kill switch,and don't use a local ground there either. Carry the other wire from the switch back to the engine and use that as your central system ground.
  9. RMWdave

    RMWdave Member

    ok i have a new engine coming. i like to press the button to kill the engine. (however, on pocketbikes. i use choke and throttle to flood kill it.... id rather do this. what do i do?)
  10. kallsop

    kallsop Member

    My engine shuts off when the choke lever is moved fully up. I never used the "kill" wire or switch.
  11. wire it up like i said but only use it in a emergency,use you choke to kill engine.

    white to stripe wire on kill and black to ground.
  12. danlandberg

    danlandberg Member

    I don't know what make you have, but my manual says the white wire has a power output of 7+ v. They say to hook the two kill switch wires to the two wires from engine to coil (cap off the white if not used for accesories) Then hook one wire (any color from kill switch) to one wire to coil, the other wire from kill switch to the other wire to coil. I hooked mine up useing one wire from kill switch to blue wire on coil, the other wire from kill switch to chasis (ground) It works, but it is still wrong to create a direct short! If there was a kill switch that worked like a refridgerator door switch (closed when out, open when pushed in) That would be the te way to go!!!
  13. danlandberg

    danlandberg Member

    Sorry C.F But I'll leave this build the way it is. The next build will be wired right.
    Last edited: Jun 16, 2009
  14. arceeguy

    arceeguy Active Member

    I instruct all my customers to use the white wire to kill the engine. No problems, and it is safer IMO.

    If you really think that using the kill switch can cause problems, just pop the clutch to stall the engine out.
  15. the white wire has a metal plug to hook to a wire(stripe one on kill switch) the blue one does too but hooks to blue wire on engine and you would have to splice it to hook to another wire,now which one sounds right.
    and if your choke doesnt stop the engine you have a airleak.
    but i really dont care where anyone hooks up there killswitch to hook it up to the 200-300volt blue wire if you want to.i prefer the 6volt wire.and i got my info from most of the bike engine websites manuals,well the good sites atleast i dont care about the others.
    and yes you can hook the white wire to the kill switch and a light at the same time.
    but i have a rechargable battery to power my lights and can light a parking lot up with them.
    Last edited: Jun 17, 2009
  16. RMWdave

    RMWdave Member

    and as for the killswitch wire it up to run without it, and put a $2 toggle on either of the blue or black wires.