r90 dyna III ignition problem

Discussion in 'Airheads' started by pdulik, Aug 4, 2010.

  1. pdulik

    pdulik .

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    i just installed a dyna III electronic ignition on my 1975 r90/6. everything ran perfect for maybe 10 miles until i came to a stop and it died instantly. came to find out the bike is losing spark at idle now. maybe a problem with the coils? everything was working perfectly up until i put the ignition on.
    #1
  2. mykill

    mykill odd

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    Since you have a history with the bike prior to the Dyna and it always worked fine, then start looking at everthing you touched. Check for power to the coils and quality of connections. Your igniton switch may also be the culprit.
    #2
  3. StephenB

    StephenB G(/)S ... what else!

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    If your coils are new and the correct ones for use with the Dyna III ignition don't read on:

    Primary coil resistance has to match the specification of the Dyna, check that. It is possible that 10min with the wrong coil killed the Dyna, when going back to points everything seems normal. If your coils are the original pair of 6V coils, about 35yrs old you could have killed the ignition too. Did you burn points rapidly and was that the reason you installed a Dyna? Signs of too low coil resistance.


    What about just simply one of your "new" wires coming loose?
    #3
  4. pdulik

    pdulik .

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    coils are the original coils. i thought it said that was ok. i didn't go through points often. the reason i put it on was because i heard such good thing about them and i wanted to make the bike more reliable. the low coil resistance is what the guy who installed it was thinking. i guess i'll check the coil resistance and the ignition. one more thing. the bike dies at idle and won't start again for a couple minutes. i don't know what that means either.
    #4
  5. Mandello

    Mandello Guzzista

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    everything was working perfectly up until i put the ignition on.

    I've had both points issues and DYNA ei issues on the road, points never took more than 10 minutes to sort out, the DYNA issue required a tow and overnighting new parts.... unless its for racing i don't see the point(s) in adding a dyna kit :p

    AlexM
    #5
  6. StephenB

    StephenB G(/)S ... what else!

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    That does point to a temperature (time sensitive) issue such as insulation failing inside the coil that start to act when the coil gets warm (heat expansion) and disappear when the coils cool down again (all back to normal). Remember, insulation inside the coil is achieved by using varnish which will age and crack with all those temperature changes over the life of your bike. If the coils are original I strongly recommend to replace them as they are initiating your combustion. If they don't work right, the best electronics won't help either.

    This isn't the only possible solution to the problem, but I would not hesiate to replace the 35yr old coils to go with a brandnew electronic ignition.
    #6
  7. pdulik

    pdulik .

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    well i put the points back in and it's running like a dream again. think i'm going to keep em on the rest of the riding season and worry about it later.
    #7
  8. kraut.burner

    kraut.burner "Fun Club" President

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    I did a little research on the Dyna III and found the installation manual. It says the dyna III was designed for use with the stock coils, or coils that have At least THREE OHMS primary resistance.

    heres the link:http://www.starracing.com/Star/documents/D35-1.pdf

    I too am thinking about using this, and getting new coils as well. Hope this helps!
    #8
  9. flemsmith

    flemsmith lurk

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    I bought a Dyna III some time ago in prep for a rebuild. So now I'm rebuilding a 78 Moto Guzzi T3, and the instructions I have are exactly the same as the ones you show, except the model number is different D37-1, and it says at least 5 ohms primary resistance. Since I have new coils I've been running with the points that are 3 ohms I'm wondering if I'll end up burning up the output amp if I install it? I may just stick with points for that reason. But the electronics unit looks the same outwardly...would they really have designed a different unit with a lower output for Guzzi's, doesn't make a lotta sense to me.

    roy
    #9
  10. photorider

    photorider Been here awhile

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    Sensor plate coming loose is a common problem which creates the symptoms you describe (it's how the system is grounded)
    #10
  11. Sabre170

    Sabre170 Been here awhile

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    Is this across both coils or across just one of the coil? In other words, 3ohms for each right and left coil for a total of 6 ohms or is it at least 1.5 ohms left and right for a total of at least 3 ohms?

    Just curious as I will likely be doing a Dyna install soon and just want to make sure I have healthy coils to use prior to install.
    #11
  12. disston

    disston ShadeTreeExpert

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    You are thinking if installing a Dyna III and to discuss that you have picked a thread from 4 years ago where the guy had a failed Dyna III. Furthermore this problem was never resolved.

    The number of threads here about failed electronic ignitions are numerous. Legion. The individual parts for a Dyna III are not available and you will have to buy another complete kit if either the Box or the Sender fails. You will also prolly not know which it is that fails so another complete kit is what you need anyway.

    If I'm not mistaken the Dyna III uses the OEM advance unit and the magnets are secured to it by set screws. Beware when you want to revert to the OEM system the points will not like the damage to the advance points cam caused by the set screws. (I once had a Dyna III)

    You have been warned about these problems so you carry the complete points ignition only now it is rusty and wet from being at the bottom of some place wrapped in a plastic bag to insure it never dries out.

    If this is for your 1978 or 1973 bike you have time tested and proven ignition systems that are easy to tend to if needed when on the road. If the Dyna III ever fails you can give up before you even start and call a tow truck. it's the only way you are going to get anywhere unless you plan to push.

    There are advantages to the Dyna III system but you can have all of those advantages and keep the points by installing a Booster instead of the Dyna IIL A Booster is the preferred equipment for many if not most Airhead riders. I don't know if we have had a Poll on that subject? Maybe it's lost with the updated software? (I seem to remember a Poll that didn't have all choices?)

    With a Booster if the Box ever fails, and they all fail someday, you merely move a couple of wires, revert back to the OEM system which is still in place on the bike and continue on your way.

    If you really gotta go with an all electronic system there are better choices than Dyna III but I think they are more expensive. A Booster is less than a hundred bucks.
    #12
  13. Sabre170

    Sabre170 Been here awhile

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    all of your opinions have been noted and were already taken into consideration. You mention other alternatives and cheaper and such.....well, FWIW, this will cost me $0 to do the "upgrade" (if you choose to call it that) as I already have a spare Dyna III lying around (long story). So, the cost is only manual labor and time.

    I am fully aware of the pros and cons of such a change, and have already done much reading on these.

    You criticize me for using a 4 year old thread referring to a failed Dyna III......I find that a bit ironic as usually the opposite is the case, normally people are given crap here for NOT reading old threads, and rather just posting a new repeat question. I've dug through the old threads, and found that this thread had already somewhat discussed my area in question, thus found it appropriate to ask it here.

    So.......with that rant out of the way, my original question still stands: The quoted minimum 3 ohm primary resistance minimum needed....is this 3 ohms per coil or 3 ohms total across both?
    #13
  14. Stan_R80/7

    Stan_R80/7 Beastly Gnarly

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    It's three ohms for the combined set of coils, across both. In other words, a 1.5 ohm coil in series with another 1.5 ohm coil will have 3 ohms. That's what points ignitions want to reduce the current load on the points and get acceptable life.

    The Dyna III's claim to fame is taking the higher resistance coils and getting more energy out of them. Some people swear by Dyna III's, but I have no direct experience with them.

    p.s. IMO, spending an extra ~ $80 to get the 3 ohm (green twin output) Dyna coil to go with the Dyna III for single plugs would be preferred and then keep the Bosch coils with the points and condenser. But, that's just me.
    #14
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  15. Beemeup

    Beemeup 1978 R100/7

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    I can't answer that but you need to check all the way to the plugs. Do you have the right resistance for the plug caps (5k ohms)? Plus the plugs themselves. I have a Boyer but ran Dyna coils for many years. Also replaced a number of plug wires and decided the coils were frying them so I tossed them and went back to stock.
    #15
  16. Sabre170

    Sabre170 Been here awhile

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    Thanks!
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  17. Brun

    Brun Been here awhile

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    I was immediately drawn to this thread title because I installed a Dyna III on my R90/6 just 5 days and 600 kms ago.

    For me this has cured a long-term issue - timing synchronisation. I have never been able to synch right and left cylinders due to an assumed bent points cam. I've never had the courage to try hitting it with a hammer and have had to compromise by having one side advanced and the other retarded. Now I have the pleasure of seeing a clean crisp F mark right in the middle of the timing inspection hole at 3k rpm. Performance has improved, starting is virtually instantaneous, exhaust note is crisper and I can see a lot more in the mirrors.

    I spent a few hours googling before making the decision to buy and read happy and unhappy stories about many different EIs. So far my story is a happy one - time will tell. I have noted Disston's warnings above and will give the old backing plate a good greasing and hope I never need it.
    #17
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  18. disston

    disston ShadeTreeExpert

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    Good luck with it Charlie. That is the same reason I had tried the Dyna III on my bike but it was blown up after about a year. That was my own fault but doesn't change how pissed I was.

    Bending the cam tip wasn't scary but it was tedious and took several attempts over several days to get it right.

    No idea how or exactly what gets bent. Just do know that re-bending can work.
    #18
  19. Werner1111

    Werner1111 Adventurer

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    I just called up Dynatek a few weeks back and was able to buy a replacement box, without the sender. They don't have the part listed on their website, but the folks there are very friendly and helpful and they do sell the box separately. I don't know about the sender. Luckily, I was able to determine that it was the box as I had one on another bike which I swapped over.
    #19
  20. disston

    disston ShadeTreeExpert

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    That's good to hear. Thanks.
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