Fried my CDI?

Discussion in '2-Stroke Engines' started by jayjmarlo, Dec 24, 2013.

  1. jayjmarlo

    jayjmarlo New Member

    So I left my bike with the gas valve open and though I may have done so before this time a few days later I found gas coming out of the exhaust pipe dripping out. When I went to start it, it ran very rough and would barely even run at all. I acting like it was flooded or had gas in the system so I tried to keep on peddling and just run it clean for like 20 minutes but it never changed. Later I tried changing the spark plug and it seemed to almost try and run again but sounded like it wasn't getting spark or gas. Than it just quit, I pulled the spark plug and it acted the exact same. I tried to test the spark plug and it didn't look like it was getting spark (I un-threaded it and taped it to the head of the engine and pedaled looking for spark and saw none. My theory is I fried the CDI, coil or spark plug and it isn't getting spark. I was thinking the CDI the little black box that feeds the spark plug. Can anyone confirm before I order a new one? If you agree any recommendations on a good one?
     

  2. crassius

    crassius Well-Known Member

    if you think there is no spark, then hold the plug in your hand and your hand on the motor and roll the bike forward - if it bites your hand, the plug is bad - if it doesn't bite, then it's the CDI or magneto
     
  3. jaguar

    jaguar Well-Known Member

    those stock CDIs have weak spark which is hard to see in the daylight.
    try it again at night.
    and turn your bike upside down and turn the engine over to get the gas out of the crankcase.
     
  4. HeadSmess

    HeadSmess Well-Known Member

    throw out china plug, buy japanese plug (ngk)

    check that the boot and lead are good. they rarely are. once again. new new, ngk!

    check that all wires are well connected, that magneto (its on the engine...search) is well mounted to engine... you need a solid earth! ie, undo the screw that holds wire, sand spot, do back up...

    check resistances on magneto... between black and frame-0, between black and blue, around 400, and if it has the white wire, cut it off!

    rarely does the cdi itself fry. does happen, but its more just to do with component manufacturing.... theres always a certain percentage that die in the first five minutes. just like i-phones. theyre worse though, they have more bits to die! (and really do make people look stupid! :jester:) )


    just prop plug on cylinder head, lift rear wheel and give the pedal on your side of bike a quick kick...


    the "weak spark" on a stock cdi still seems capable of jumping 10mm or more in my experience... over an inch at full throttle... then they fry!
     
  5. Big Red

    Big Red Active Member

    I try and TRY, And ya do it again Headsmess, calling a COIL a magneto. The magneto has NO wires connected to it, IT's just a magnet that spins inside the coil;.And just so ya know Jayjmarlo, 99% of the time IT'S THE COIL. Yeah, CDI's go out too, IN ten years I've seen maybe two bad ones, Coils are $12 and sometimes free shipping. IF ya think ya got a lot of fuel in the case, Drain the tank and turn it upside down, pull the plug and turn the peddals turning the engine till no more gas comes out. And remember to ALWAYS turn off the petcock when ya park it.
    Big Red.
     
  6. HeadSmess

    HeadSmess Well-Known Member

    no.

    http://www.thefreedictionary.com/magneto

    a MAGNETO is ANY device using a magnet and coil to produce alternating current, commonly in relation to ignition systems. the bit that spins is the ROTOR, be it a magnet or not.

    the entire unit, that horseshoe bit of steel, the magnet, AND the coil of wire, are collectively called a magneto.

    can also be called a dynamo, which is usually when its used simply as a generator.

    the step up transformer that changes the low voltage to a high gap jumping voltage for the spark, is commonly called a coil. from "induction" or "rhumkorff" coil)

    otherwise, i completely agree. more often than not the magneto is fried. the CDI unit itself, almost never!
     
  7. Huotalicus

    Huotalicus Member

    frirend can u give me more detail as to what you mean ??? so if i get zapped by the plug in my hand holding it against the engine case and turn engine // does that mean the spark plug is bad??? i thought it meant it was ok??? because its producing spark
     
  8. crassius

    crassius Well-Known Member

    if you can feel the spark in your hand, but can't see a spark at the plug, then the problem is either a bad plug or you aren't turning the engine fast enough to see the spark

    this test will not tell you if the CDI is timed right tho
     
  9. Fabian

    Fabian Well-Known Member

    :iagree:

    The stock standard CDI is amazingly reliable, and i've also found aftermarket CDI's to be surprisingly reliable.
     
  10. Huotalicus

    Huotalicus Member

    Dear friend how can I verify the cdi n the magneto are ok
     
  11. velzie

    velzie Member

  12. crassius

    crassius Well-Known Member

    the CDI & coil make a spark at the right time - if you can see the spark or feel it in your hand, then both are working at making the spark - if the timing is bad, there is no way to test that except with a real CDI tester or by trying a new CDI
     
  13. Big Red

    Big Red Active Member

    Just because ya GET a spark don't mean it's a hot enough spark. A weak coil will fool ya every time. Sometimes you can get it running on a weak coil, but it will run like CRAP. Most of the time I dont bother even testing a coil, They are only $12 so I keep an extra on hand and switch it out. If it runs better, It was the coil,LOL. 99.999% of the time in a weak or no spark situation, IT'S THE COIL.
    Big Red.
     
  14. jeffuehrer

    jeffuehrer Member

    I recently had a misfiring issue. I swapped out the spark plug (NGK-B6HS) first to see if it made a difference and it didn't. Then I swapped out the plug wire and boot (stock) to an automotive plug wire and boot. Those plug wires like to break at the wall edges and I end up having to dig them out...grrrr! No change. I then swapped out the stock cdi with another stock cdi and voila! That is the first cdi that has gone out on me in the four years I've been mbing. I like to keep everything stock if I can, save for the spark plug, hub adapter with sprocket, and chain tensioner. However, that automotive plug wire and boot really make a difference and I can tell the connection is so much better. Every time I look for a Jaguar cdi I can never find one and how much of a difference does it make? Also, when I pulled the first spark plug to troubleshoot I noticed it was the undesirable-black as tar-looking color. That means I am running rich, correct? Rich meaning too much fuel to air ratio. My idle screw is in all the way but if I back it out it doesn't idle at all. My needle is in the second from the top position. If I had an air leak wouldn't the color of my spark plug be ash white? My thought is that my oil (Amsoil Saber Professional 2-cycle) to gas (Circle K 87 octane) ratio is too high (approx. 35:1). I don't ride WOT hardly ever. I keep it at 80-90% (22mph-26mph) throttle so I have a little extra when needed. I live in a warm, dry climate with some moderately steep hills. I have a 66cc, 2-stroke, well broken-in (1800 miles), stock carby, stock muffy, stock head. She runs good but I would like her to run great. What do you guys think I need to do in order to get that sweet chocolate brown/tan color on my spark plug? Any advice would be greatly appreciated. Thanks mbers!
     
  15. jeffuehrer

    jeffuehrer Member

    Well, I just finished the last of my 35:1 mix and mixed up a batch of 45:1. I checked my spark plug and it was a little lighter than before. It was tar black because the last 12 miles was when the CDI was misfiring so the spark was intermittent which resulted in the dark color. Regardless I still have a little bit of fuel build-up at the bottom of my muffler but not enough to drip. It should ideally be dry, shouldn't it?
    Thanks for all your help guys, you're all wonderful.
     
  16. jeffuehrer

    jeffuehrer Member

    I took her out to the gun range today and she ran quite well. She doesn't really warm up though until about a mile before she does 25mph. Could just be because of an upgrade and headwind though. The idle sounded fine and the throttle response was sufficient. I increased the average mph to 19.3 and the max to 27.9mph. After a total of 21 miles today I pulled the plug and it was tan and dry, the muffler also had no oily residue at the base. I think I have found the sweet spot as far as my fuel ratio goes (45:1). I am pleased with my bike and have finally reached Elysium, so to say...of course until the next inevitable problem arises. Thank you for your patience Jeff, you've earned it. Sometimes the best advice already exists within all of us. Mileage update-1,845
     
  17. Huotalicus

    Huotalicus Member

    hey guys just wanted to add that a customer came in today with a non starting engine, i knew it was the cdi, so off i went to examine, dc.ed the killswitch and tried , no go, then changed the magneto coil, and wallah!!!! once again the 2 stroke comes back to life....varooooommmm!!! also blew a gasket the other day , head bolts came loose but didnt tightten them down before riding again and so boom,,,the head gasket went, and thats it.... changed out and off i went again !!!! I TRULY BELIEVE THAT THE MAGNETO COIL, IS THE CULPRIT MOST TIMES WHEN YOUR ENGINE WONT FIRE, BE IT NEW OR NOT, SOMETIMES MOISTURE WILL FORM WITHIN YOUR CASE OR EVEN THE OUTSIDE AND BECUZ YOUR WIRES RUN DIRECTLY TO THE COIL , IT WILL ALMOST DEFINATELY LEAD ANY MOISTURE ALONG THE CABLE, WHICH IS DIRECTLY CONNECTED TO THE ENGINE VIA blue black and white cables... thisis very imprtant to keep dry, once wet your engine wont fire ever again !!!!! if you have spark but wont start or fire, then check this immediately ..... if you didnt know this it can really do your head in badly..... no joke!!! spark is spark, question is is it strong enough, and is it constant ? just cux you have soark doesnt mean its strong enough to ignite engine...../
     
  18. Fabian

    Fabian Well-Known Member

    That's exactly how it is: moments of pure pleasure interrupted by periods of mediocre engine performance, interrupted by periods of total frustration that takes you to the deepest depths of utter despair.

    Climbing your way out of the hole, with grit and determination and a warrior like spirit, to find and conquer the gate keeper of Elysium shows the true strength and robust nature of the male spirit that knows only one way of approaching an insurmountable problem: claw your fingers into the situation and hang on for the ride; fighting like hell to tame the vicious beast and bring it into order to teach it civility.

    Crikey, that almost sounds like my last relationship, only that the engine needed a lot less effort to make it behave with an acceptable level of civility.
     
  19. jaguar

    jaguar Well-Known Member

    Here's the deal; a weak spark system can produce a spark when the plug is out of the engine, but not when it is inside the engine. That is because the higher pressure requires more voltage to spark the gap. Another reason to switch to an aftermarket CDI/coil when increasing the cranking pressure.

    Many "bad" magneto coils aren't bad at all. Where the screws contact the metal needs to be sanded clean, that's all.
     
    FurryOnTheInside likes this.
  20. Fabian

    Fabian Well-Known Member

    :iagree:

    The energy required from the magneto (using a CDI) to jump an electrode gap is proportional to pressure.
     
Loading...