New everything and still zero spark

Discussion in 'Electrical' started by batteway, Jan 28, 2014.

  1. batteway

    batteway New Member

    Alright then, heres my problem. Motor was running great for months and then boom! No spark! and of course 6 miles frome home. Have been through everythin including replacing everything. New magneto and magnet, plugs, wires, and a lightning cdi and still no spark. I dont know where to look anymore so any help is much appreciated.

  2. BigBlue

    BigBlue Active Member

    What engine do you have?

    AKA: BigBlue
  3. batteway

    batteway New Member

    Pk80 with cr.machine top end kit. 6.0 cc head. Sbp pipe, the only thin I have left to replace would be the bottom end. Was looking at the dax but not sure if it will allow me to use the top end I have.
  4. Fabian

    Fabian Well-Known Member

    Sounds like we are suffering from an almost identical problem and have used almost identical problem solving methods.

    My situation is a little different in that the engine runs, but it has a persistent "spark miss", or what feels like a spark miss below 3,300 rpm; getting progressively worse as the engine rpm is lowered.

    I have changed the entire electrical system with new components, including 2 new magnetos and one old magneto from another engine that works. I have changed two brand new Jaguar CDI's and one Jaguar CDI from another engine that worked correctly, as well as installing an original OEM CDI.

    I have changed three sets of Magnecor spark plug leads (all brand new) and 3 new NGK spark plugs.

    I have changed out the original Jaguar coil for 2 brand new Jaguar coils and also the coil that's included in the standard CDI.

    In desperation i have also removed the original engine (which was a rebuilt engine) and replaced it with another fully rebuilt engine, then in further desperation i have installed an engine that previously worked well, but was removed because i lightly scratched the crankshaft trying to replace a crankshaft seal.

    So in total i have replaced the magneto 3 times - the CDI 4 times - the engine 3 times - the spark plug 3 times - the spark plug leads 3 times - the coil 3 times, if you include the coil in the OEM CDI.


    the spark miss replicates itself in every combination i try,

    oh yes,

    and i have been up and down with jetting and removed the diaphragm carburettor and gone back to a standard NT carburettor, followed by purchasing a brand new NT carburettor.
    The end result is that the spark plug miss is ever present.

    I have even tried making up batches of fuel from different fuel companies.

    This is the first time in the history of playing around with these 2-stroke Chinese bicycle engines that i "can't" fix the problem, and yes, the killer switch is disconnected from the ignition system and the (magneto) white wire is isolated.
    Last edited: Jan 29, 2014
  5. Fabian

    Fabian Well-Known Member

    I am using the same cylinder head. It's proven to be an excellent design; allowing much cooler cylinder head temperatures than any other cylinder head i have tested.
  6. Sgt. Howard

    Sgt. Howard Member

    Have you looked at the magneto ground connection? That's where I found a cold solder joint to the magneto frame... re-solder that wire to a round lug and connect to a mounting bolt, see if that don't cure it
  7. BigBlue

    BigBlue Active Member


    Also look at Grubee website about installing a new magneto coil: Mystery.html

    AKA: BigBlue
  8. Fabian

    Fabian Well-Known Member

    How likely is it that 3 magneto coils would have a bad ground connection (two of them being brand new) and a magneto coil that worked perfectly on a previous engine?
  9. velzie

    velzie Member

    Maybe rust on the ground to the magneto? Try sanding the connection...

    I feel for your problem as I went through something similar. I can only suggest getting a multimeter and testing all electrical signals from the magneto through the CDI and to the spark plug.

    Good luck.
  10. Fabian

    Fabian Well-Known Member

    There is no rust.
    I have sanded the ground wire connector and the back of the magneto coil arms to ensure a good earth.

    Luck is eluding me, and i'm having great trouble accepting such a concept. The only thing that can solve this problem is a Feng Shui expert; with typical advise to place threatening lion statues at strategic points around the bike, to cast out evil electrical demons.
  11. HeadSmess

    HeadSmess Well-Known Member

    check the plug threads! yes, in the head! carbon isnt particularly conductive.

    check that the head is "continuous" with the rest of the engine! its only contact with the rest of the engine electrically is through the cylinder STUDS. the cylinder has a fibre base gasket correct? thats not conductive!

    im sure we tried new plugs ?

    that can cause complete loss of spark... but replacing EVERYTHING should have resulted in SOMETHING that worked.... unless, as i said...heads not earthing. where are you holding the plug to check for spark?

    multimeter will soon tell you if its the magneto not working, narrowing the field down somewhat.

    can play a part in be far more suspicious of seals etc when its erratic...what may feel like spark, simply isnt...unless you have a data logger saying that it definitely is the spark missing at times... seals or crankcase gasket are my suspicions. or a dirty carb.

    cus yes, im getting the same splutters on one particular engine...and so far ive been too lazy to dig into it. i got others that are running fine, so why bother :jester:
  12. Fabian

    Fabian Well-Known Member

    I have tried using 3 new NGK Spark plugs in 3 different heat ranges: BP6HS, BP7HS, BP8HS
    I have always used BP8HS plugs. The 6 and 7 heat range plugs made no difference to the spark miss.

    I have had crankshaft seals completely fail and also partially fail.
    My current situation most definitely "feels" like a spark/ignition problem, but i cannot say 100% for sure that it 'is' an ignition system problem.

    I have connected a wire to the spark plug and attached it to an couple of engine case bolts to bypass the potential insulator issues of carbon on the spark plug threads - the problem still remains.

    Why would the spark miss become present at 3,300 rpm and progressively get worse as rpms are reduced?
    The miss is present at higher rpms but it's barely noticeable, and the hotter the engine gets, the more the spark miss is reduced. When the engine gets stinking hot, the spark miss almost goes away.
    Logic would say that it should be an air/fuel ratio issue being a temperature moderated problem, but would 3 different engines all have identical problems, including one engine that ran perfectly when it was previously pulled out of the bike and reinstalled to try and cure the problem?
  13. Fabian

    Fabian Well-Known Member

    Where can i get a data logger to check for spark continuity?
  14. keatonx

    keatonx Member

    All these things remind me of my 1997 merc 9.9 outboard motor (2 stroke). A few years ago it started knocking really hard at around 3000 rpm. If you were cruising along at that speed every once and a whole it would kick really hard, puffing out a big cloud of smoke, jerking the tiller handle and often even stalling the motor. Then one day last year I was driving it to the marina and when I let off the gas, it stopped cold and wouldn't start. I managed to get it running by turning the idle speed screw in all the way with some scissors and revving the cr*p outta it. Ever since then it starts right up when cold, then once it's somewhat warm the idle becomes nonexistent. If you hold it WOT it will slowly clean out and rev happily, but it has no power under load and is really slow to accelerate(at times it refuses to pull a tube faster than walking speed). I've got it to idle by leaning the idle by one turn. And if I pull the mechanical advance at idle it'll run great.
    So far I've checked for a sheared flywheel key which would cause the ignition retard (from the knocking) and that was good, if I remove one spark plug to test the individual cylinders if I remove the bottom plug it runs absolutely no different than with both in. And if I remove the top plug it barely runs at all; I need to pull the mech. Advance and throttle butterfly just to get it to start. Switched coils, the botom cylinder's still bad. Plugs are the same. Top crank seal is good (can't easily check the bottom one). Only one carb so that isn't the problem. Only one trigger coil so that isn't the problem. I'm assuming the stator is one big coil and doesn't have a coil for each cylinder. That leaves the CDI (or switchbox as the fancypants manual would say). I'll be replacing that in the spring. It's a $150 part so it better fix it:(
  15. keatonx

    keatonx Member

    And one time it would randomly shock me through the boat (aluminum), and only run with the engine cover off. When I put it on it would die. The cover was pulling my good cyl's spark plug wire out of it's hole in the coil:jester: but the other problems still remain...
  16. jsph7501

    jsph7501 New Member

    you should have a kill switch sometimes the switch goes bad or it may ground on to your frame take the black and blue wire off the coil wires that may do it or take cover off magneto make sure shaft that turns magnets is"nt bent