Major electrical wierdness!

Discussion in '2-Stroke Engines' started by mikesbike, Apr 22, 2007.

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  1. mikesbike

    mikesbike Guest

    Hi guys, I'm new to this foum. I've got about 900 miles on my 48cc bike. It went about 200 miles like a champ. Then all of a sudden the weirdness that has become worse and worse. It is very difficult to start. It will only start if the kill switch is activated. It runs very poorly, (4cycleing?) If I can catch it just right I then have to push the button again and an IF I am really lucky it might go into a good 2cycle mode. If I don't kill the motor, it will run very nicely until I shut it off again. The thing won't even think about firing unless it gets grounded first. I've spent hours messing with wireing. I got a new magneto and it would not run at all with the new one under any circumstances. Can someone stear me to a fix? Would it be the CDI? I figure as good as it runs when it does start thats not it.

  2. gone_fishin

    gone_fishin Guest

    let's start at the beginning:
    CDI to Magneto
    blue to blue/green (kill switch belongs here)
    black to black
    white capped or for light (for troubleshooting, disconnect any light)

    plug-cable fully seated in cdi & boot firmly on plug

    edit: correct plug gap posted below.

    all good so far?

    welcome to MBc 8)
  3. mikesbike

    mikesbike Guest

    I have the kill on the white. If the white is not grounded to the motor or frame. (Killed) the motor will not start. No way.
  4. gone_fishin

    gone_fishin Guest

    using the replacement magneto, are you willing to try the proper wiring config for us?
  5. mikesbike

    mikesbike Guest

    I'll try anything. My starting ritual is pretty embarrasing! My bike looks good. I look stupid trying to get it to go.
  6. gone_fishin

    gone_fishin Guest

    we all do!

    make sure the connections are tight & well-insulated from the frame, and from each other, too.
  7. thatsdax

    thatsdax Guest

    Wiring problems..

    Spark Plug gap should be 15-20 thousands. 30 thousands works ok for some autos..But not for this motor. Make you gap about half of that. There is not much to the electrical. Magneto, CDI, and plug wire and cap. Check all wire connections, Including the brass snap inside the plug cap. make sure you remove the spark plug crown and just have the threads showing. White wire is for Headlight and not for kill. It will work for kill but using it for kill can cause excessive quick heat ups and eventually ruin the Coil. Ohms between blue and black should be around 260 ohms disconnected. There is no way to check the CDI. Thanks..Enjoy the ride..
  8. gone_fishin

    gone_fishin Guest

    ok, .015-.020 it is...thanks dax.

    edited my blooper, i'm gonna go looking for other examples of the wrong info.
  9. mikesbike

    mikesbike Guest

    Thanks for the tips. I have an automotive coil wire to the plug. (NGK) gap'd at .030 It has to have a crown. Have dialectric grease at both ends of the plug wire. I'll try the different gap and try to get rid of the white wire? I don't care about the light.
  10. gone_fishin

    gone_fishin Guest

    dax has corrected the proper gap to .015-.020, i see you missed that.

    just cap off the white wire til later or never.
  11. JosephGarcia

    JosephGarcia Guest

    I'm pretty sure I don't, a small push and release the clutch, starts up as if I had a key ignition. I dont have to be moving fast either, I mastered the skill of starting my motor. :grin:
  12. gone_fishin

    gone_fishin Guest

    i'm pretty sure he was talking about looking dumb while trying to start it when it just ain't starting :p

    that came across as if you think i haven't figured it out yet, i'm sure i've only misinterpreted, eh? sabrina-II sparks right up, but it helps if i have spark...i bet i've looked pretty dumb pedaling that engine up and down the street, first cussin', then pleading, then stopping to pant for a while...then try again, why? i don't know. then try the other plug again, why? i don't know that either :roll:
  13. JosephGarcia

    JosephGarcia Guest

    Yeah I'm like that once in awhile (rarely though.) but my bike doesn't have pedals, so I look worse. running then jumping on.

    I look even worse when I have to turn off the motor at a stop light (if i'm there for over a minute, i shut off my motor, assuming it will start right away, which it does during the afternoon only.)

    I know the whole cursing and pleading deal.

  14. mikesbike

    mikesbike Guest

    Ok folks, I tried to run it without the white wire hooked up to ground. No way! won't run. BUT, I re-gapped the plug to .015 and it starts much better. Not great but better. It does not seem to have as much top end power with the new plug gap though. I have not tried my other magneto yet. (No time) Thanks! for the help to this point. Its forward progress.
  15. your stock plug shouldnt be run for 200 miles straigh if thats what you meant by 200 miles and then it ....the stck plug are hot and after 25 miles of windin oner' the gap opens up youll want to get a new plug and if your a journier Id get a cooler plug
  16. duivendyk

    duivendyk Guest

    Have you ever disconnected the kill switch wiring directly at the white wire on the engine and checked if the engine would start?.It's very odd that partially shorting the generator coil with ground on the white wire would help in getting the engine started,if anything it would reduce the output on the blue wire to the CDI unit.The new generator coil does not work wether or not the white wire is grounded?.About the only thing left is to replace the CDI unit(and the the plug cable) and hope the generator is OK
    When performing any ignition tests make sure that there ALLWAYS is a sparkplug connected to the cable and that the body is grounded.The insulation on the CDI output is probably marginal, once it breaks down you can kiss the CDI good bye.
    Last edited by a moderator: Aug 24, 2008
  17. relaxxx

    relaxxx Member

    White wire to ground??!!! If you try starting a motor with white or blue actually grounded it will not fire and you run a very high risk of frying your magneto if it's not already fried. If it runs at all like this its because of bad wiring and it's not really being entirely grounded because if it was grounded it will just be stone dead! For trying to troubleshoot a motor, disconnect anything from white and only hook the blue and black to CDI. Forget about the Kill switch it will only cause misery and add unnecessary failure points. At least get the motor running properly before even considering adding the kill to the mix. This thread is like troubleshooting gone bad, way way bad!!