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R90/6 with dual plugs

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
 
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
 
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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
 
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
 
Don -

My discussion was focused primarily on the non dual plugged setup, the D35-1 kit. I said that but you cut off your quote:

The Dyna III does not eliminate the wasted spark setup on Airheads, at least for the non dual plugged package.

I have this kit on my /7, so I feel I know a good bit about it. If you look at the first picture posted by donbmw of the D35-1 kit, the wires to-from the coils are just as they are in a standard points system, although the Red wire seems to be extra. The Brown wire is the switched ground that used to go to the points but now uses the Dyna box to indicate when to switch the "points" open so that the coils can collapse and generate the spark.

The second picture has two dual plug setups. One is D35-1 so that's that same as above. The D35-2 is indeed different...I've never really paid much attention to dual plug wiring for Dyna. It appears that 12v is coming to each coil and if the Brown and Black wires act as switched grounds, then it appears that the D35-2 setup can switch one coil independent of the other. Further evidence as you point out is the need for a tach module because the D35-2 kit will fire each coil half as often, resulting in the wrong tach reading. The tach monitors the collapse of the coil to determine the RPM. So that evidence seems to point to the D35-2 setup as not a wasted spark.

From what I understand, the longer the "points" are closed, the coil is being saturated deeper and deeper, resulting in a stronger spark when the field collapses. But the time of saturation should be not be too long as the coil will heat up. This can be a concern when doing maintenance work with key on-ignition off and the points closed...the coils can become very hot over a period of time. Whether the change to a non-wasted spark situation with the D35-2 results in too long of a time for saturation, I doubt it but it's something to consider. It could mean a slight affect on the coil life, but it's probably not quantifiable.

Timing of a wasted spark system with the D35-1 package lets you use a timing light on either spark plug wire to see what is happening to the other cylinder. This is where you might see the ghost S-marks. But with the D35-2 kit, you would have to move the timing light back and forth on the plug wires to see how the other cylinder is firing. This is probably the difficulty mentioned in previous posts about trying to get both sides timed correctly in this situation.
 
Don -

My discussion was focused primarily on the non dual plugged setup, the D35-1 kit. I said that but you cut off your quote:
Sorry about that!

But the D35-2 can be configured to use only two plugs total with no waste spark, by simply grounding out one of the Dyna HV ignition coil spark plug wires on each side and only using the other to one plug each. Such is not possible with the D35-1. The DS1 will have a waste spark regardless of two or four plugs regardless of how it's configured. That's all I was trying to say there.
I have this kit on my /7, so I feel I know a good bit about it. If you look at the first picture posted by donbmw of the D35-1 kit, the wires to-from the coils are just as they are in a standard points system, although the Red wire seems to be extra. The Brown wire is the switched ground that used to go to the points but now uses the Dyna box to indicate when to switch the "points" open so that the coils can collapse and generate the spark.
Yes, I realize all that and that's the same system my R75/5 has. I went from points to the D35-1 with the stock BMW six volt coils at first. I did the dual plugging later, which means I change the stock six volt autotransfomer "coils" to the Dyna true transformer "coils".
The second picture has two dual plug setups. One is D35-1 so that's that same as above. The D35-2 is indeed different...I've never really paid much attention to dual plug wiring for Dyna. It appears that 12v is coming to each coil and if the Brown and Black wires act as switched grounds, then it appears that the D35-2 setup can switch one coil independent of the other. Further evidence as you point out is the need for a tach module because the D35-2 kit will fire each coil half as often, resulting in the wrong tach reading. The tach monitors the collapse of the coil to determine the RPM. So that evidence seems to point to the D35-2 setup as not a wasted spark.

From what I understand, the longer the "points" are closed, the coil is being saturated deeper and deeper, resulting in a stronger spark when the field collapses.
There is a time limit besides heat. When the magnet field has no new movement, nothing new happens until it is released. IOW, if it is closed for 1 seconds or two seconds, it make no difference at all when the field is collapsed (that's when you get your HV spark) because nothing new happens if pure DC is on the coil between 1 and two seconds. The first few milliseconds of being closed is when it makes a difference for when it opens the circuit. Closed much longer than that, there is no benefit when opened up for the HV spark.
But the time of saturation should be not be too long as the coil will heat up. This can be a concern when doing maintenance work with key on-ignition off and the points closed...the coils can become very hot over a period of time. Whether the change to a non-wasted spark situation with the D35-2 results in too long of a time for saturation, I doubt it but it's something to consider. It could mean a slight affect on the coil life, but it's probably not quantifiable.
The D35-2 will have longer coil life because the coils are only used half the time of the DS-1. They will also draw half the current per coil. Means slightly better spark, less heat, more reliable. But IMO, perhaps not enough difference in engine performance to even be concerned with, and the DS-1 should still last many years of riding anyway. But don't expect the Dyna coils to last forever, but I assume the 12 volt coils will last a bit longer than the six volt coils, simply because the 12 volt coils only fire half as much as the six volt coils.
Timing of a wasted spark system with the D35-1 package lets you use a timing light on either spark plug wire to see what is happening to the other cylinder. This is where you might see the ghost S-marks. But with the D35-2 kit, you would have to move the timing light back and forth on the plug wires to see how the other cylinder is firing. This is probably the difficulty mentioned in previous posts about trying to get both sides timed correctly in this situation.
Yep, agreed.

-Don- Reno, NV
 
I doubt that not all plugs fire at the same time, dual plugged or not.
The difference is not two or four spark plugs. The difference is the D35-1 or D35-2 Dyna setup.
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
There's an added pickup coil on the cam, which is in sync with the side it fires. Both the D35-1 and D35-2 have two pick up coils on the cam (unlike the stock points), but the D35-1 keeps the waste spark, but the DS2 does not. The D35-2 fires each coil separately, unlike the D35-1 that fires both ignition coils at the exact same time, every time with every other spark wasted on each side.

What makes you think things will get out of sync when the engine is stopped???

-Don- Reno, NV
 
I was just thinkin... Anybody got two inductive pickup timing lights and a kick starter on one of these bikes? :brow

My buddy just found a real nice '82 R100RS just like mine. Same colour even and it was dual plugged. At first I got jealous. Now I've got a headache.. and not the least bit upset that I'm wasting spark. :D
 
Tried to stop myself, but here's a schema used to install an old accel amp. to R90 using standard points trigger and dual andrews coils. Works and that's all I know.
 

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here's a schema used to install an old accel amp. to R90 using standard points trigger and dual andrews coils. Works and that's all I know.

That's the set-up I have on my '75 R75/6. Did the install in the late '70's and the bike now has 218,xxx miles on it and still going strong. As stated above, the points act as a trigger for the amp. and do not burn. I have not changed points since the late '70's. Just have to adjust every few years for any wear on the points cam block.

Mark
 
That's the set-up I have on my '75 R75/6. Did the install in the late '70's and the bike now has 218,xxx miles on it and still going strong. As stated above, the points act as a trigger for the amp. and do not burn. I have not changed points since the late '70's. Just have to adjust every few years for any wear on the points cam block.Mark
That's the first time I've seen dual plugging with stock points. Nothing wrong with that setup, but I would still prefer to not have any points to adjust at all.

Of course, you still have the waste spark and six volt ignition coils, just like my Dyna setup on my 71 R75/5. Your current through the points is almost nothing because of a transistor in the module which triggers the coils when it detects the points on the base of the transistor. The transistor draws almost nothing and supplies the high current to the coil primaries.

-Don- Reno, NV
 
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