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Thread: R90/6 with dual plugs

  1. #31
    Registered User toooldtocare's Avatar
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    Don, mine also has (had since it is now sold) wasted spark, this system does not get rid of it, just gives you two circuits, one for each coil. I could tell when I timed it with one timing light I saw two timing marks, like I did with points on my R90S before it was dual plugged and had a Dyna III. That is because the timing chain gets longer as time goes on, causing incorrect timing on one side. When I reversed the plug wires so each coil fired plugs on each side of the bike I still got two marks about 1/8 apart.

    When I used two timing lights, one from each coil buy on the same cylinder with swapped plug wires, I could see multiple timing marks, that is the two pairs already mentioned about 1/4 inch apart. I tried moving the pickups on the rotor plate and I could get the marks close, but never on top of each other, meaning one plug still fired first with the swapped plug wires. Thus, swapping plug wires on dual plug bikes with dual pickups is probably a waste of time since the plug that fires first would ignite the gas, the second plug would be firing too late to do anything.

    Wayne

  2. #32
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    Quote Originally Posted by toooldtocare View Post
    Don, mine also has (had since it is now sold) wasted spark, this system does not get rid of it, just gives you two circuits, one for each coil. I could tell when I timed it with one timing light I saw two timing marks, like I did with points on my R90S before it was dual plugged and had a Dyna III. That is because the timing chain gets longer as time goes on, causing incorrect timing on one side. When I reversed the plug wires so each coil fired plugs on each side of the bike I still got two marks about 1/8 apart.

    When I used two timing lights, one from each coil buy on the same cylinder with swapped plug wires, I could see multiple timing marks, that is the two pairs already mentioned about 1/4 inch apart. I tried moving the pickups on the rotor plate and I could get the marks close, but never on top of each other, meaning one plug still fired first with the swapped plug wires. Thus, swapping plug wires on dual plug bikes with dual pickups is probably a waste of time since the plug that fires first would ignite the gas, the second plug would be firing too late to do anything. Wayne
    I am not sure if that proved anything. You have two pickups, so it will only be matched exactly to every other firing. Have you ever checked the static timing (engine NOT running) to see if there is a spark when both valves are open on that side of the engine? That will prove a wasted spark.

    Also, do you know if your Dyna coils (transformers) are six volt ignition coils or 12 volt ignition coils? If they are six volt, you have a waste spark for sure because that means both coils fire each time, as the coil primaries are then proved to be in series. But because of that wire going to the crossover wire between the coils, it could mean that is a common for two 12 volt coils and that would mean you most likely do NOT have a wasted spark. It's hard to tell for sure by your schematic because it's not showing the entire circuit, such as what that wire ("long red wire") does that goes from the Dyna box to the crossover wire between the coils.

    Mine has no other wires going to the crossover wire which proves I have two six volt coils with the primaries in series which also proves I have a wasted spark.

    But yours must be different for a reason and that wire from the crossover wire to the box must be doing something. My guess, unless you know for 100% certain, is those are 12 volt Dyna coils and then you most likely have no waste spark, each pick-up coil trigger only one ignition coil.

    That is unlike mine where either pick-up coil triggers both ignition coils every time, firing all four plugs at once, but still can be adjusted to slightly different timing on opposite sides for the actually used spark.


    -Don- SF, CA

  3. #33
    Administrator 20774's Avatar
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    Don -

    Doesn't the presence of the short cross-over wire indicate that this is a wasted spark setup? Power is going to flow to one coil, through the windings, then to the other coil, through the windings and then out to essentially ground. When the Dyna box/sensors get into position, the power will be cut and both coils will fire. It almost looks like that they are suggesting that the left coil provide spark for the left plugs with the right coil providing spark for the right plugs.

    I still don't see how the Dyna III system can be anything other than wasted spark. And I've not heard of any Airhead setup that is anything but wasted spark.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
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    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  4. #34
    Registered User toooldtocare's Avatar
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    I remember back in the day when cars had points and Heath Kit (and others) provided CDI (Capacitor Discharge Ignition) systems to give a hotter spark. I installed one on my very hard to start 74 Camaro, it helped a lot.

    They worked by charging a capacitor to a much higher voltage than the normal trigger voltage provided by the points, then discharged it through the coil, thus giving the hotter spark. I assumed that is the main purpose of the Dyna, or any solid state ignition. Not to eliminate the points, but to give that hotter spark. On this diagram I see two trigger wires, one to each coil, two pickups. Nothing there suggest that they eliminated the wasted spark since the cam rotates at the same speed and the sensor would pass the pickup and provide that signal at the same speed as a set of points opening allowing the magnetic field in the coil collapse giving the spark.

    With dual plugs you get two hot sparks in the engine, one on each side of the piston, shorting the burn time. Sort of like burning your candle at both ends, fuel runs out faster. This is why you have to retard the timing too, fuel burns faster and it would ping (knock) if you do not.

    Am I thinking right on this?

    Wayne

  5. #35
    Registered User donbmw's Avatar
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    What no one has said yet there are two types of the Dyna III. Standard DYNA III (D35-1) and the DUAL DYNA III (D35-2).

    Attached is out of the installation manual for the D35-1. I will Post another for the D35-2 that shows how to hook up for dual plugs for both systems.
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    1975 R90/6, 1980 and 1982 R65, !959 TR3A Triumph Car

  6. #36
    Registered User donbmw's Avatar
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    Second attachment
    Attached Images Attached Images
    1975 R90/6, 1980 and 1982 R65, !959 TR3A Triumph Car

  7. #37
    Registered User toooldtocare's Avatar
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    Don, I think you are right. After reading my own post again, and about the coils you posted, the Dyna III does eliminate the wasted spark.

    I came to that conclusion by what I said, "the cam rotates at 1/2 the engine speed." If my memory serves me correctly, their was only one trigger which is used by both pickups. Since the cam rotates 180 degrees for each revolution of the engine, than it would have to have two pick ups 180 degrees apart to fire the cylinders at 360 degree intervals, which it does.

    Boy, never though I would be taxing my brain so much this early in the morning. Learned something today.

    Wayne

  8. #38
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    The Dyna III does not eliminate the wasted spark setup on Airheads, at least for the non dual plugged package. All the Dyna III is is an electronic trigger for when to collapse the field in the coils to generate the spark. Since both coils are being flooded with 12v (in on one coil, through the cross-over wire, out the second coil to ground), once the Dyna III system finds that one of the sensors is tripped, 12v to both coils will be cut and the spark to both plugs is generated. It can work no other way.

    The benefit of the second pickup is to allow independent adjustment of when the spark fires every 360 deg of crank (180 deg of cam) rotation. With the original points set up, due to variations in the cam that the points ride on and other wear situations, the spark may not be at the optimum time for either cylinder. With points, you typically statically time the engine to one cylinder and generally take what you get for the other cylinder. You can still put the timing light on the left plug wire and see the results of the plug firing at each 180 degree of cam rotation. This is where you'll see the double image which can be the timing chain but it's also the minor variations in the advance unit.

    The dual plug setup might be different, but I highly doubt it. Just having two pickups doesn't necessarily mean that the wasted spark is eliminated. If the coils are interconnected and being fed the same 12v in series, then the system is still wasted spark.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
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    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  9. #39
    Registered User toooldtocare's Avatar
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    My head hurts.

  10. #40
    '92 R100GS '81 R100/t brittrunyon's Avatar
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    Quote Originally Posted by toooldtocare View Post
    My head hurts.
    Same here!
    1992 R100 GS, 1981 R100/t, 2007 F 650 GS

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  11. #41
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    Quote Originally Posted by 20774 View Post
    Don -

    Doesn't the presence of the short cross-over wire indicate that this is a wasted spark setup?
    No! Not with that wire going from the Dyna module to the crossover wire.

    For an example. think if there is 12 volts on the center crossover wire, supplied by the wire from the Dyna module, and each end of the secondary ignition coils are grounded. Or vice versa. If there were no wires going to the grossover wire, only then would it prove two six volt coils. And if there are two six volt coils, why have the wire going to the crossover wire from the Dyna module? What's that wire doing? The fact that wire goes to the crossover wire makes be believe those are 12 volt Dyna coils. But not enough is shown on the schematic for me to be certain.

    Now if somebody else can guess what that wire from the Dyna module to the crossover wire would do in a six volt coil system . . . . I cannot think of anything and keep on coming back to 12 volt coils which would make that wire a necessity.

    I know for certain that San Jose BMW sold two Dyna systems for my 71 R75/5. One had a wasted spark (mine) and the other did not. MOST people, if not all, who did NOT already have an Dyna electronic ignition setup would go for the system that got rid of the wasted spark, since they had to buy all new ignition stuff anyway. Since I put in the Dyna system well before I dual plugged the bike, I had two options. Replace my entire Dyna ignition system, coils, module, everything OR keep everything which includes the wasted spark. I chose to keep the waste spark as I am unclear if there is any real advantage of getting rid of it other than the ignition system drawing half as much current, which isn't much anyway.

    And I have the advantage that I could easily put points back in (but then I should put in a thingie to reduce the high point current from the Dyna coils). However, that ain't going to happen. I have a complete spare Dyna setup here, so there will never be a need to go back to points.


    -Don- SSF, CA

  12. #42
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    Quote Originally Posted by donbmw View Post
    Second attachment
    You proved my guess was correct! The bottom schematic gets rid of the wasted spark unlike the top configuration.

    Thanks, -Don- SSF, CA

  13. #43
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    Quote Originally Posted by 20774 View Post
    The Dyna III does not eliminate the wasted spark setup on Airheads,.
    Did you read the part above on the schematic about it "firing the cylinders sepeartely". That means there is no waste spark in the D35-2.

    It makes no difference in waste spark if there are four plugs or two, if one plug on each side. With the D35-2 setup, simply short out the bottom plug wires to the engine and you will still have no waste spark in that setup. The top plug will get the increased power from the coil. All of it. None of the HV will be grounded out as I have explained in a previous post. Now you clearly will have no waste spark on a two spark plug setup. Would be unusual, but possible. It would run fine, just don't retard the ignition timing as you would with using four spark plugs.

    BTW, I can think of no reason to have 12 volt coils on an airhead other than to get rid of a wasted spark. To get rid of a waste spark, each coil must be dedicated to only one cylinder, as shown in D35-2. And it even says there it is using 12 volt coils.

    Likewise, I can think of no reason for six volt coils to have a wire from the module to the crossover.

    The crossover wire proves nothing. But the wire from the dyna module to the crossover tells me something is going on, such as getting rid of a waste spark.

    Only the D35-1 keeps the waste spark in the above schematic.

    -Don- SSF, CA
    Last edited by DonTom; 01-17-2013 at 06:05 AM.

  14. #44
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    One more thing PROVES there is no waste spark. Read what it says about the tachometer in the bottom schematic.

    That's because at 4,000 RPMS the tach will only shown 2,000 RPM's. Can you all guess why?

    Yep, no waste spark for the tach to count! There's only half the normal sparking, so the tach has to be modified to read twice normal.

    Anybody here still unclear, or does that prove to everybody here that there is NO waste spark in the bottom configuration?

    And my head is not yet even beginning to hurt. . . .I enjoy figuring this stuff out.

    -Don- SSF, CA

  15. #45
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    I doubt that not all plugs fire at the same time, dual plugged or not. I talked to Silent Hektik about their system. It would be doable, if the boxer engine was a 2-stroke.
    How do you know, when it??s time to spark, which side is it going to be? You would need to look at the valves.
    OK, so you do that, and set your system to fire left - right - left. Fine, and you take off.
    Some time you need to stop your bike, turn everything off. When you are starting again, how is your ignition going to know which one to fire?
    Hans
    Norway

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