Jaguar & Lightning CDI timing curves

Discussion in 'Performance Mods' started by jaguar, Mar 21, 2014.

  1. jaguar

    jaguar Well-Known Member

    I finally got hold of a Lightning CDI to test it against a Jaguar Performance CDI on the bench. Below is a graph showing the timing curve difference.
    The spark strength of the two is the same, using the same high voltage coil. The main difference is that the Jaguar CDI retards the timing at a higher rate than the Lightning above mid range RPM. How/why the Lightning designer thought it unnecessary to give a normal retard curve is beyond me, but it's in my favor. If you will look at motorcycle ignition curves you will see that the final timing is always close to 10 degrees BTDC at peak RPM and that the downward slope towards that starts early. Take a look at these graphs to see what I'm talking about:
    The RM curve to watch is the full throttle one since motorized engines at peak RPM are always at full throttle. The RM peaks at around 9200RPM, typical of 250cc motocrossers.
    In conclusion it looks like the Lightning is too retarded at around 3000RPM, which limits power, and too advanced at high RPM, very similar to the standard CDI, which limits power and rpm and causes vibration. Now I see why he never has made available the timing curve.
    I'm sure now Huffy will huff and puff like a big bad wolf and say his makes more power, blah blah blah without giving a good technical explanation of why. Soon JNMotors will have dyno results for a modified engine using both CDIs so we can all see the actual power difference. But apart from power there are two other things to consider; vibration and reliability. More retarded timing at high RPM lessens the vibration from these engines. Why? It counters the imbalance. The flywheels have too little metal removed at the counter-balance holes. Reliability is improved by retarding high RPM ignition because having the ignition happen too early means the peak combustion pressure will be happening more around top dead center instead of around 10-15 degrees after top dead center. That early peak means much more pressure on the bearings which wears them out early.
    FurryOnTheInside likes this.

  2. seb1008

    seb1008 New Member

    I have the cdi, just waiting to put my motor back together.
    Jaguar I tried to email you at with gmail and yahoo but both said delivery failed.
    Is there a way to contact you about your intake manifolds? I guess I do not have enough posts to use the forum.
    I apologize for this being off topic.
  3. jaguar

    jaguar Well-Known Member is the right address.

    If I was a customer of the Lightning these would be my gripes (in addition to ignition being too advanced):
    1) the key mechanism is not waterproof. How long does it last in a rainy climate?
    2) it doesn't come with a cool sticker
    3) the wires need to be stripped and soldered
    4) no heat shrink tubing is provided to seal and strengthen where the wires will be soldered together (unless of course the owner just crimps the connections which is a less secure way to do it which leaves the copper exposed to water intrusion which leads to corrosion)
  4. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Are you sure that it doesn't come with a cool sticker? :D
  5. velzie

    velzie Member

    At how many degrees BDC does the exhaust port open on a unmodified cylinder? How about on one modified as per your recommendations?
  6. jaguar

    jaguar Well-Known Member

    no sticker, I'm sure.

    click on my signature link to read about standard and modified port durations for the 48cc and 66cc
  7. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Are you sure you are sure?

  8. jaguar

    jaguar Well-Known Member

    You can doubt me if you want to but mine didn't have a sticker. If others are receiving them then that's cool.
  9. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    How much HP does a "cool" sticker add?

    Yes, the HD Lightning comes with a sticker and I am so sorry you did not get one........

    Hey, are you sure that you really got a HD Lightning?
    Maybe you bought the knock off of your CDI?
  10. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Why is your CDI going up in flames?
    Faulty wiring?
    Cheap components?
    Too retarded?

    Why are your input wires so short? Is wire too expensive in South America?

  11. jaguar

    jaguar Well-Known Member

    the only CDIs causing engines to go up in flames is the stock CDI (on the engine in the following picture) and the Lightning CDI because both have overly advanced ignition which increases engine temperature and contributes to engine-destroying detonation.
    The wire size on the Jaguar is adequate if you don't leave the wires flapping in the wind. The length is now being made longer.
    Components are imported from the States, same quality. (The topic of components has already been gone over in another post.)
    As always the competition doesn't talk technology or about the engineering reasons for ignition timing curves, just little nit-picky stuff that equates to school children making fun of each other for little clothing differences.
    Of all people to take the side of a CDI with incorrect timing curve I wouldn't think it would be a race promoter! backwards world
  12. electron

    electron New Member

    I've seen that picture. The guy apparently spilt/leaked fuel onto his hot motor. I think this is where the "Junkuar" CDI gets it's magic smoke from.

    People have had problems (and I only looked a 2 pages of search results).

    "My problem with Jaguars CDI is that i bought it from him and after the internals came un-soldered he tells me to go to JNM to complain. Well guess what, JNM didn't sell me the CDI. It's a shame they (JNM) claim how much more reliable the Jaguar Racing CDI is over the stock. Jag's works better but is not more reliable. I find myself torn. I can't repair mine for the life of me because my soldering skills suck. However my father in law builds computers, i think my solution is simple. I'll have him reman the current model and replicate a few more for back ups. "

    "I bought a JAG CDI last month and finished my bike a week or so ago. The CDI lasted about 1 minute and died."

    Just build your own (look in my album). An incorrectly adjusted Junkuar CDI can do more damage, sooner.
  13. jaguar

    jaguar Well-Known Member

    el, an engine has to be hotter than is a normal maximum to ignite fuel that leaks onto it.
    both advanced ignition and high compression contribute to excessive engine temperatures.
    The Jaguar CDI retards the ignition back to where it should be to not contribute to excessive engine temps.
    Yes it had a reliability problem that has been solved. I am well aware of that. All assembly now is under my watchful eye (as an electronics technician since 1977) and I personally test each one to make sure its timing advances and then retards as the RPM rises.
    None of my competition has this kind of tester. I know because they aren't commercially available. I designed and made my own.
    So when you buy a competitors CDI you can't be sure if its timing curve is functioning. Maybe its not but you don't know better since all you have to compare it to is the standard CDI.
  14. butre

    butre Well-Known Member

    gasoline auto ignites at around 400, doesn't it? if some of that spill landed on the header it would be up in flames with or without a jaguar cdi

    wouldn't a timing light and an engine be the only test equipment you need to determine the timing curve? both of those are not only commercially available, but in just about every garage
  15. butre

    butre Well-Known Member

    if anything, retarding the timing would make the header hotter
  16. jaguar

    jaguar Well-Known Member

    yes it's true that if the gas dripped onto the header that would be enough to light it. But if it lit by contact with the head that means the head was at least 495 degrees which is too hot for an aluminum head. It can crack and warp at that temp.
    yes the CDI's could be somewhat tested on an engine but I highly doubt the makers are going to that much trouble.