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Thread: Dyna III timing woes

  1. #1
    sneakers563
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    Unhappy Dyna III timing woes

    OK, probably not a Dyna III problem per se...

    I've got a '71 /5 on which the PO installed a Dyna III electronic ignition. While going through my the-wait-for-a-running-bike-is-almost-over tune-up, I ran into a problem when adjusting the timing dynamically: I get a double S (idle) and double F (~3000 rpm) image. According to the Clymer manual, this means I need to replace the advance unit (which the Dyna system retains).

    I don't have any experience with the Dyna III or this type of problem, so I thought I'd ask: anything else to consider before springing for a new unit?

    There was an earlier thread I came across where the poster had a similar issue and several people advised him to go with a Dyna III to fix the problem. Is there some way to compensate with the Dyna III that I'm not aware of? Would any of the other common electronic ignition systems (Boyer, Omega) solve the problem?

  2. #2
    Administrator 20774's Avatar
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    Do I understand that the Dyna III is already installed and you're seeing a double timing image? If that's the case, the Dyna III can fix the problem.

    The Dyna III has a small donut with a magnet embedded in it that has been secured to the end of the camshaft...actually it's on part of the advance unit. There are also two small coils (Hall effect sensors I believe) that are located opposite each other on the Dyna plate. Each of these coils are held in place by some very small bolts which you should be able to see.

    Basically, you can now rotate these coils independent of each other so that each cylinder fires at the best point and eliminates the double image. You'll need to fiddle with these coils. I'm not sure which coil controls which cylinder as you look at the front of the bike. Make a small change on one of the coils...see what's happened to the images. If it gets better, keep doing what you did. Otherwise, adjust the other way or try the other coil.

    Once you set it, you should be good for thousands of happy miles!
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  3. #3
    --Tony AnnapolisAirhead's Avatar
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    ...sounds like Voodoo magic, Kurt.
    '83 R100RT'd
    '71 R75/5 SWB
    '06 KLR 650

  4. #4
    Administrator 20774's Avatar
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    Quote Originally Posted by AnnapolisAirhead View Post
    ...sounds like Voodoo magic, Kurt.
    Tony, sometimes it does take some smoke and mirrors... I've been pretty happy with my Dyna "magic" for a lot of years...
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  5. #5
    sneakers563
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    Cool

    Yes, it is installed: that's excellent news! I'll give it a try this evening.

    For my info, though, could you help me understand a bit more why this would work? From what you've written, I'm inferring that the problem is that the timing of the spark isn't the same in both of my cylinders. But why would that produce a double image if my timing gun is only hooked up to one spark plug wire? Why would making changes to the timing of the right cylinder (for instance) change the image I see when my timing gun is hooked up to the left spark plug wire?

    As you can guess, though, I really understand very little about how the electrical system of the bike works.

  6. #6
    Bill the Cat geisterfahrer's Avatar
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    Our airheads use a "wasted spark" ignition system, so both plugs fire simultaneously. The Dyna III allows you to independently adjust the timing of each spark impulse so that each cylinder on its compression stroke has "perfect" timing; for the spark being wasted on the other cylinder, it makes no difference.

    Go to the Dyna web site dynaonline.com for detailed instructions on how to do this.

  7. #7
    sneakers563
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    Aha! Thanks.

    Also, Kurt, your advice has really helped me since I got this bike a few weeks ago. If you're ever in Tucson, there's some free beer with your name on it.

  8. #8
    --Tony AnnapolisAirhead's Avatar
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    Ditto on the beer offer to you Kurt, if'n ya happen out to my neck of the woods. I have an odd setup, but won't hijack this thread with it.
    '83 R100RT'd
    '71 R75/5 SWB
    '06 KLR 650

  9. #9
    Administrator 20774's Avatar
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    Quote Originally Posted by sneakers563 View Post
    Aha! Thanks.

    Also, Kurt, your advice has really helped me since I got this bike a few weeks ago. If you're ever in Tucson, there's some free beer with your name on it.
    Quantify "some"... Ha!!
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  10. #10
    --Tony AnnapolisAirhead's Avatar
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    Quote Originally Posted by geisterfahrer View Post
    Our airheads use a "wasted spark" ignition system, so both plugs fire simultaneously.
    ....you can 'see' this on this link: http://www.bmwmoa.org/forum/showthre...027#post521027
    '83 R100RT'd
    '71 R75/5 SWB
    '06 KLR 650

  11. #11
    James.A
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    Quote Originally Posted by 20774 View Post
    Do I understand that the Dyna III is already installed and you're seeing a double timing image? If that's the case, the Dyna III can fix the problem.

    The Dyna III has a small donut with a magnet embedded in it that has been secured to the end of the camshaft...actually it's on part of the advance unit. There are also two small coils (Hall effect sensors I believe) that are located opposite each other on the Dyna plate. Each of these coils are held in place by some very small bolts which you should be able to see.

    Basically, you can now rotate these coils independent of each other so that each cylinder fires at the best point and eliminates the double image. You'll need to fiddle with these coils. I'm not sure which coil controls which cylinder as you look at the front of the bike. Make a small change on one of the coils...see what's happened to the images. If it gets better, keep doing what you did. Otherwise, adjust the other way or try the other coil.

    Once you set it, you should be good for thousands of happy miles!
    Having 2 pick-up coils on the "points plate" essentially turns the BMW single breaker ignition into the equivalent of a BSA or Triumph ignition that has a point set to fire each coil. Unless the Dyna III fires each coil individually you still have a wasted spark system. What you would want to do to attempt to compensate for the ghost image timing mark is to choose a cylinder for a base line. Then determine which of the pick-up coils (Hall effect sensors) is being excited when your chosen cylinder is at TDC on the compression stroke. I'd use the "ignition hot/static timing method" to determine this. After getting the first cylinder timed, use your timing light and dial in the other pick up coil. Again, this is the breaker-less equivalent of the Lucas ignition. On the Lucas ignition, it would be necessary to key off the other plug wire for the second point set.

    However, the issue still at play when you've done this is the fact the generally accepted cause of ghost timing images is, A) timing chain wear or, B)radial run-out of the ignition end of the camshaft or, C) wear on the advance mechanism.

    Definition: Ignition hot/static timing method. This is when you pull both spark plugs to defeat compression. Then put them in their respective plug wires and lay them on the cylinder to afford a ground path for the ignition spark. Then turn your motor over by hand, with the ignition on, using either your kick starter or an allen wrench in the bolt that holds the alternator rotor in the end of the crank. Look for the spark across the plug gap and/or hook up your timing light and make adjustments accordingly. You are looking for spark when the "S" mark on your flywheel is observed through the aperture on the left side of the motor. If you are using the allen wrench, be sure to turn the motor the same direction as if it were running.

    As always, if you must remove the front cover, dis-connect the battery negative terminal before doing so. Then, re-connect as desired.

    Good luck, and all the best,
    James A...
    Last edited by woodnsteel; 12-03-2009 at 01:44 PM. Reason: content

  12. #12
    Administrator 20774's Avatar
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    Quote Originally Posted by woodnsteel View Post
    Unless the Dyna III fires each coil individually you still have a wasted spark system.
    I'm pretty sure the wasted spark feature of the bike is still there...but now you have the ability to choose when to fire the cylinder that is on the compression stroke independently. Just as the points system is a switch, the Dyna III is also just a switch with two switch points in the system. Everything at the coils is exactly as it was before, so it's still wasted spark. So there's no need to switch the timing light to the other lead.

    I can think of another way to figure out which small coil controls which cylinder in a static sense. One has to pay attention to the position of the magnet on the donut at the advance. As it rotates, it will approach one of the coils...of course when it reaches a specific postion it will "trigger" that coil...at which time both plugs will fire. So then the question is which cylinder is at or near TDC on the compression stroke. The usual manner of watching the timing marks and the valve action will tell you that.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  13. #13
    James.A
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    Quote Originally Posted by 20774 View Post
    I'm pretty sure the wasted spark feature of the bike is still there...but now you have the ability to choose when to fire the cylinder that is on the compression stroke independently. Just as the points system is a switch, the Dyna III is also just a switch with two switch points in the system. Everything at the coils is exactly as it was before, so it's still wasted spark. So there's no need to switch the timing light to the other lead.

    I can think of another way to figure out which small coil controls which cylinder in a static sense. One has to pay attention to the position of the magnet on the donut at the advance. As it rotates, it will approach one of the coils...of course when it reaches a specific postion it will "trigger" that coil...at which time both plugs will fire. So then the question is which cylinder is at or near TDC on the compression stroke. The usual manner of watching the timing marks and the valve action will tell you that.
    Hey Hurt I was hoping you were on. Cool, The method I like to use is to put my thumb over the spark plug hole.

    Regarding switching plug wires; I thought that through and edited the instructions. This is hold over knowledge from my days in the kingdom of darkness.
    Last edited by woodnsteel; 12-03-2009 at 01:53 PM. Reason: content.

  14. #14
    Administrator 20774's Avatar
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    Quote Originally Posted by woodnsteel View Post
    The method I like to use is to put my thumb over the spark plug hole.
    James -

    I've done that too...definitely a positive indication you're on the compression stroke. Lately, I've gone to the "watching the valves" routine, because I'm hunched over the rear of the bike, tranny in gear, and pulling the tire around. My arms just don't reach that far!! Plus, I'm trying not to remove the plugs if I don't have too. I'm leary about messing up the spark plug hole threads...I'd rather deal with valve cover holes instead.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  15. #15
    James.A
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    Quote Originally Posted by 20774 View Post
    Plus, I'm trying not to remove the plugs if I don't have too. I'm leary about messing up the spark plug hole threads...I'd rather deal with valve cover holes instead.
    Fear not. Besides, if you want to release the motor compression, you need to pull the plugs. If you get to where you are routinely pulling the plugs, you'll have little to worry about regarding the plug holes. Just don't over tighten them, and I like to use anti sieze. Been doing it several times a year for many years.

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