Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Magnetic induction (I think)

  1. Mar 24, 2004 #1
    I am at the very end of my pitiful little rope and I do need some serious help with my electric/magnetic induction problem.
    About Me: I am a machinist and a motorcycle rider/racer, I know nothing about electricity or terms used other than I have found it rather unpleasant to use my body as a resistor. OOPS!
    History: This is concerning the ignition system on a four-cylinder, two-cycle motorcycle. In all my wit and wisdom I decided to ash can the stock ignition on my racer and go with a magneto type system. The system I bought is designed for a two-cylinder engine and I have a four-cylinder engine however my engine fires two cylinders at the same time. I bought two “dual coils” to ignite my spark plugs. This system uses a magnetic rotor on the crankshaft and two sets of primary coils to supply the two high-tension coils with power. (I do know better than to call power “juice”)
    Problem: This engine will absolutely not run under 2500 RPM, the spark plugs do not spark under 2500 RPM and this makes the engine very difficult to start and keep running under normal conditions.
    Solution: (Like I really have one)I replaced the primary coils with those of a higher output and this is the only way I was able to get the engine to start in the first place.
    Question: Can I rewind the primary coils I now have with more wire to produce a higher output at lower engine speeds or am I just dead in on the track with this ignition?

    Any and all suggestions and help are greatly appreciated and thanks in advance,
  2. jcsd
  3. Mar 24, 2004 #2


    User Avatar
    Science Advisor
    Gold Member

    What my question would be is if the engine runs correctly with the high tension coils that are made to go with the mag kit. I realize that you would be only running on 2 cylinders, but is it possible that the double output coils are asking for more than the mag can provide? Twice the spark is going to take twice as much power from the mag. Up to this point, the only way you have been able to get this much power is by running the engine fast. Just curious, but what is the rotor like on the crank? Magnets imbedded in it? Reluctor type thing? Is the rotor gap and all that stuff set up right? I assume it is electronic timing and not points, but if you will excuse my 'terminology' I will refer to the device that opens the circuit as 'points' even though it is probably a transistor. What I was wondering concerning the 'points' is where about is the magnet/reluctor in relation to the primary coil when the 'points' open? Is this adjustable? It can be VERY critical. Is this engine a 4 cyl opposed? Look forward to your reply.
  4. Mar 24, 2004 #3
    Do you have something to control the timing other than the Hall effect pickups? What ignition system did you actually install?
  5. Mar 24, 2004 #4

    I believe this is the original RG500 ignition

    Dead cylinder ignition setups don't require that much more power to fire a single cylinder; however, your running a 4 cylinder engine which is firing two times more than the magneto was designed for at low RPM's.
    Last edited: Mar 25, 2004
  6. Mar 25, 2004 #5
    Gods own lightning?

    Thanks for the replies folks.

    I will try to address all the questions asked to the best of my very limited abilities.
    A picture is worth, well, you know so,
    The system I have is the analog #70104, which is designed for a two-cylinder engine, I am using dual output coils also made by PVL.
    This engine, a Suzuki RG500, is a square four in configuration, it has two 180 degree crankshafts and fires the left front and right rear cylinders together then the right front and left rear cylinders together.
    I do have a set of PVL single output coils that I could try but I haven’t done this, as was stated, I would only be running on two cylinders.
    The aluminum crank rotor is approximately 2.5” in diameter and has two rather large and very strong magnets set at 180 degrees from each other. This crank rotor also determines when the ignition event will take place, this is adjusted by rotating the primary coils (also 180 degrees in offset)on a common mounting plate.
    I was very careful in setting up this system with all the clearances and such, being a machinist by trade I do have all the proper measuring tools for this little task.

    faust9: Dead cylinder ignition setups don't require that much more power to fire a single cylinder; however, your running a 4 cylinder engine which is firing two times more than the magneto was designed for at low RPM's.

    RG500: This has me thinking (I know) since my system has two magnets on the rotor and also two primary coils I wonder if I couldn’t wire the output coils to ignite only one cylinder each? The way I originally set this up was so that one coil would ignite two cylinders at the same time <sigh>

    The output coils both have their own little ignition control module or “black box” if you will. I believe these can be seen at the PVL link, the output coils are the red and black ones pictured.

    Yes, the link you sent http://edj.net/2stroke/rg/ServiceManual/06-05.GIF
    is a diagram of the stock ignition system that I have removed. I removed the stock system for a few reasons, it is big and heavy as in rotating mass, I no longer need a charging system since I do not use a battery and the flywheel size does not allow me to properly fit a 35mm carburetor to #3 cylinder. The standard carburetor size is 28mm for street use.

    I am going to attempt to unearth the little RG500 today and try switching the spark plug wires so each coil will only ignite one cylinder at a time. I will keep you posted of my results. Thinking (I know) back, when I first installed this ignition, I was having trouble in getting a spark at kick start cranking speeds with all of the spark plugs out of the engine. I could get a visible spark at times however it took quite a healthy kick to produce said spark. This is the reason I changed over to the higher output primary coils, with the standard primary coils there was no spark at all at cranking speeds.

    I am off on my quest to place Gods own lightning into my little engine.
    Last edited by a moderator: Apr 20, 2017
  7. Apr 21, 2004 #6
    A suggestion was made that I might want to try using a rotor with stronger (state of the art) magnets. Of course I would have to make a rotor such as this and test it to a high RPM since the rotor is only inches away from my left foot and I have become rather fond of the use of my left foot over the years. I have the ability to safely test a small item such as this to a maximum of 35K RPM for several hours.
    Any comments or suggestions?
    thanks in advance...
  8. May 8, 2004 #7
    RG500 PVL solution

    I'm the new kid here but I reckon this is solvable
    I've done a lot with pvl ignitions and I want to fix this!
  9. May 8, 2004 #8
    Rex again! Just to add we have done our own CDI circuit and different generator coils to help low-speed sparking! We now have sparks at 400 rpm. We have a system on the Kork Ballington KR500 4 cylinder so the RG must have a solution!-Rex
  10. May 8, 2004 #9
    Hi Rex,

    No, I haven't come up with a solution to my perplexing little problem yet and I will be more that happy to hear what you've come up with on your KR500.
    I'll email you.
  11. May 20, 2004 #10
    The final solution:
    Rex @ Rex Caunt Racing (see above posts) has offered to make my RG500 ignition work and work well for me. He has designed a all new CDI box to better cope with my ignition needs and he is working on this little project as I am writing this. Rex has also sent me pictures of the inner workings of the CDI unit he has made up for my RG500 and has lead me through the CDI process step by step in order for me to understand what is going on inside of that mysterious little CDI box.
    If anyone on this forum should ever be in need of motorcycle ignition help I can highly recommend RCR to set things right.
    I also wish to thank this forum and it's members who have helped me during my time of need, thank you.

    A very happy RG500
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook