Topic: I got 99 problems and a coil failure is all of them.

[Shenanigans]

1976 CB550. I have a Dyna-$. Last time I took it off I forgot to re-time it and since I am having some backfiring/loss of power issues, out comes the timing light. My workspace was pretty dark and when I blipped the throttle I could see a small yellow spark between the "points" plate and the engine case. Around all three parts that touch the block. It only happens in the 4000+ rpm range. Setting the timing made them go away but just out of curiosity I would like to know exactly WHY that happens. I though that this was sometime a symptom of a bad condenser but I dont have points anymore!

[scottly]

Don't know much about Dyna. Is the "plate" non-conductive?

[HondaMan]

Do you have the old Dyna, where the backplate is a circuit board, or the new one, with the metal backing plate?

The circuit board ones would sometimes damage their printed copper traces, then they grounded poorly. Take yours off, if it is that type, and add some small jumper wires from the pickup grounds to the plate screws to improve the grounding. In real worn cases, you may have to solder the wires to the traces near the pickups.

[Shenanigans]

Its the newer style solid backing plate.


My bike now seems to have issues. At idle she seems to run fine but once I get 200 feet down the street 1-4 stop firing. Once I stop and idle 1-4 seem to return.

[HondaMan]

This sounds like the gaps are set wrong between the magnet and the triggers. Check your owner's manual (I think it is 3 pages long) for the Dyna: I think those metal-plate ones are 0.035" gap or so. If they are too close or too far apart, the spark will be very weak.

[bucky katt]

mine did that right before the trigger for 2-3 went south. i went to points and a hondaman ignition (runs amazingly well Mark, better than it ever did the hot coils and dyna)

[bistromath]

Sounds like a bad ground connection. Wouldn't really have believed it since both the engine case and Dyna plate are made of metal, but there ya go. Make sure the screws are tight and everything is corrosion-free. Is your engine case painted inside there?

[HondaMan]

mine did that right before the trigger for 2-3 went south. i went to points and a hondaman ignition (runs amazingly well Mark, better than it ever did the hot coils and dyna)

I think you are the 3rd Dyna-replacer since January this year! It must be a bad year for Dyna?
Normally they aren't so bad. 

[bucky katt]

and the one i got rid of last week was the 3rd and final dyna trigger unit i'll ever replace.

[Shenanigans]

I have a habit of only tightening down one bolt while I am setting the timing. That way I could loosen it easy and adjust it quick with the timing gun. So it probably did have a bad ground connection. That seems to make sense. I have strong spark back where I should, the problem was a worn wire between the Dyna and the coil. If it DOES return soon I know that the Dyna is probably giving out. I have never had any trouble with my Dyna trigger. It does only have around 12000 miles on it however...

[dave500]

ive had the boyer brandsden conversion for three years,/20,000kays,,no trouble,with stock old coils,you cant tamper with the curve though,the advance unit comes out,,and the black solid state box replicates it.,i like it.,id like to use a hondaman on my next bike though so i have both.

[Shenanigans]

So I ordered a new Dyna and some more ignition wires. I guess I ordered the wrong one so I have to wait until tomorrow to send it back then wait another week.

Anyways I stuck the new ignition wires on and had no problems the first night of riding, but while on the way back the problem I have been fighting with returned. However I did figure out how to replicate the it!
Keep in mind it will never do this at sustained RPMs. Only when I come to a light to and the bike starts to idle. Or sometimes when I let the RPMs drop when I am slowing down or whatever. No loss of power or any kind of hint before it does it.

Once it does this the bike will not start again for a while but after maybe 3 or 4 mins. It then always seems to just suddenly start right back up, full power. Sometimes I can keep the bike from dying but it has NO power. Almost like its running on 2. But I have to rev it to keep it from dying.

There is a tiny spot on one of the wires going from my ignition to the coil that has been wore down just enough to where a little part of the wire is exposed. I figured this was the problem and I wrapped and wrapped and wrapped it. But it did not seem to help.

Just to see I shorted this wire while the bike was running to the frame and it killed the engine, however it would not start back up. Just like on the side of the road I would kick and kick and it would sort of backfire a little but would not start. I shut it off waited a couple mins and kicked it back over and she ran again. Just the same as what was happening.

So does the coil take time to "recover" after its been shorted out? If so this would seem to explain my problem...

[Shenanigans]

Where can I buy a new seal for my Dyna-S? I seem to have a leak from the little hole in the back?   

I think this may be my problem. Messing with it some more I can only get it to do it with the motor hot which points to this too. When it gets hot, I get a weak spark. Still spark on all 4 just really weak.

So what caused this, why did Dyna Fill my ignition with coffee creamer?

[HondaMan]

That white stuff is heat sink compound, used to couple the heat from the Dyna trigger into the metal backplate. It's not a leak: it is applied in between the two metal surfaces. If you have lost most of it (looks like it's gone for the most part), then install some more: if you don't have access to the electronic white type, then use the silicone dielectric grease that you can get for sparkplug boots. It's almost as efficient as the white stuff at transferring heat.

[scottly]

Heat-sink compound might be found at Radio Shack; at least I used to get it there. The local 'Shack doesn't carry as much of that type thing anymore, but if you need a cell-phone battery, I'm sure they can hook you up!

[Shenanigans]

Since I cant really ride it around to get it hot I put a heat gun on the Dyna-S triggers and sure enough after a min. they start causing the engine idle erratically then the motor dies. Once it dies, the bike can not be restarted right away. It just backfires and after a couple of mins of letting them cool the bike will start again.

I remember Hondaman saying something about triggers getting electronically leaky when they heat up. I am going to re-time the bike right now then test it again just to double check. I think I can hold a multimeter, heat gun and timing light at the same time?


So I think the verdict is my Dyna went south...

[scottly]

If you don't have the heat-sink compound, the triggers can't transfer the heat to the backing plate....

[Shenanigans]

If you don't have the heat-sink compound, the triggers can't transfer the heat to the backing plate....

I dont have any but there should be some at the shop I can snatch tomorrow. I should of said that's WHY the triggers were going south.


Hey scottly, I have been trying to organize a bike run here in PHX for a while I have 3 or 4 people that have said they are in but I am trying to get more. Your bike running? You want in?

[bistromath]

Having been overheated doesn't necessarily mean the trigger's gone bad. I mean, if you took a NEW dyna and put a heat gun on it you'd see the same thing. Before you call it dead, put a new layer of heat sink grease on it (use a real thin layer) and try it out.

[scottly]

If you don't have the heat-sink compound, the triggers can't transfer the heat to the backing plate....

I dont have any but there should be some at the shop I can snatch tomorrow. I should of said that's WHY the triggers were going south.


Hey scottly, I have been trying to organize a bike run here in PHX for a while I have 3 or 4 people that have said they are in but I am trying to get more. Your bike running? You want in?

[scottly]

Hmm, totally messed that up...
No, my bike isn't running, not that it would take much more than a new battery to cure, but it's also not currently registered or insured. Also, I'm about 80 miles N of you, and tend to avoid Phx like the plague!
Thanks for the invite, though!

[HondaMan]

Since I cant really ride it around to get it hot I put a heat gun on the Dyna-S triggers and sure enough after a min. they start causing the engine idle erratically then the motor dies. Once it dies, the bike can not be restarted right away. It just backfires and after a couple of mins of letting them cool the bike will start again.

I remember Hondaman saying something about triggers getting electronically leaky when they heat up. I am going to re-time the bike right now then test it again just to double check. I think I can hold a multimeter, heat gun and timing light at the same time?


So I think the verdict is my Dyna went south...

This is the classic scenario of the trigger failure.
The heatsink compound only improves the heat transfer about 3%-5% over not having it there at all: it's not a big difference, but since the desing has always been near the "ragged edge" thermally speaking, it adds a little insurance for the designers.

Once the triggers have been heat-damaged (by whatever originally caused it), they won't go "back" again. They will always act the same: OK when cold, erratic and too much timing advance (at idle) when hot. Eventually, they will short altogether, causing weak or no spark.

I have mostly seen this happen when the bikes had 3-ohm coils, either Dyna or Accel coils, without Dyna's recommended inline resistor. (Not that they sell one: they don't, never have.  )

[Shenanigans]

Since I cant really ride it around to get it hot I put a heat gun on the Dyna-S triggers and sure enough after a min. they start causing the engine idle erratically then the motor dies. Once it dies, the bike can not be restarted right away. It just backfires and after a couple of mins of letting them cool the bike will start again.

I remember Hondaman saying something about triggers getting electronically leaky when they heat up. I am going to re-time the bike right now then test it again just to double check. I think I can hold a multimeter, heat gun and timing light at the same time?


So I think the verdict is my Dyna went south...

This is the classic scenario of the trigger failure.
The heatsink compound only improves the heat transfer about 3%-5% over not having it there at all: it's not a big difference, but since the desing has always been near the "ragged edge" thermally speaking, it adds a little insurance for the designers.

Once the triggers have been heat-damaged (by whatever originally caused it), they won't go "back" again. They will always act the same: OK when cold, erratic and too much timing advance (at idle) when hot. Eventually, they will short altogether, causing weak or no spark.

I have mostly seen this happen when the bikes had 3-ohm coils, either Dyna or Accel coils, without Dyna's recommended inline resistor. (Not that they sell one: they don't, never have.  )

Ouch, those are the exact symptoms I seem to have and what do you know, 3-ohm coils. I retarded the ignition enough to where when it does warm up and start to wander (timing wise) it will not go far enough to kill the bike but there is nothing above 7000 rpms. As long as it can get me the 7 miles to my truck tomorrow morning before work, I am in the clear.

I read a couple of reference to to the Dyna III box, or something like that. I think I have one on a parts bike, I dont know exactly what it does but can it be of any help?

And HondaMan, take care of my motor when she finally arrives.

[Fritz]

The heatsink compound only improves the heat transfer about 3%-5% over not having it there at all: it's not a big difference, but since the desing has always been near the "ragged edge" thermally speaking, it adds a little insurance for the designers.

Just one comment about thermal compound (aka heat sink compound, thermal grease, heat paste,...):
Don't overdo it. It does not transfer heat as well as bare metal. Its purpose is to fill gaps between two surfaces that are meant to transfer heat in order to ensure even heat dissipation. If you have a transistor bolted to a heat sink and the mating surfaces are not 100% parallel you will have some spots in between that are filled with air. Air is not transfering heat very well, so the transistor will see hot spots here that might lead to partial overheating. The thermal compound should only make sure that there's no air between the heat sink and the part that is to be cooled. It should only be applied so that any gaps, pits, indentations are filled.

[HondaMan]

Since I cant really ride it around to get it hot I put a heat gun on the Dyna-S triggers and sure enough after a min. they start causing the engine idle erratically then the motor dies. Once it dies, the bike can not be restarted right away. It just backfires and after a couple of mins of letting them cool the bike will start again.

I remember Hondaman saying something about triggers getting electronically leaky when they heat up. I am going to re-time the bike right now then test it again just to double check. I think I can hold a multimeter, heat gun and timing light at the same time?


So I think the verdict is my Dyna went south...

This is the classic scenario of the trigger failure.
The heatsink compound only improves the heat transfer about 3%-5% over not having it there at all: it's not a big difference, but since the desing has always been near the "ragged edge" thermally speaking, it adds a little insurance for the designers.

Once the triggers have been heat-damaged (by whatever originally caused it), they won't go "back" again. They will always act the same: OK when cold, erratic and too much timing advance (at idle) when hot. Eventually, they will short altogether, causing weak or no spark.

I have mostly seen this happen when the bikes had 3-ohm coils, either Dyna or Accel coils, without Dyna's recommended inline resistor. (Not that they sell one: they don't, never have.  )

Ouch, those are the exact symptoms I seem to have and what do you know, 3-ohm coils. I retarded the ignition enough to where when it does warm up and start to wander (timing wise) it will not go far enough to kill the bike but there is nothing above 7000 rpms. As long as it can get me the 7 miles to my truck tomorrow morning before work, I am in the clear.

I read a couple of reference to to the Dyna III box, or something like that. I think I have one on a parts bike, I dont know exactly what it does but can it be of any help?

And HondaMan, take care of my motor when she finally arrives.

If you have a working Dyna II module, and some good Dyna S triggers, you can connect the triggers to the III box, then connect the III box to the coils. The triggers then switch the box (much like mine) and the box switches the coils. The III box is rated for up to 6 amps, IIRC. They were notorious for short life, by when Terry in AUS sent his in for "repair", they sent him a new one for $50, not bad. I once got a drag bike 750 in a basket: it had 3 Dyna III modules, all dead, in the midst, and a set of 3 ohm coils. 

Did you already send that Four? I'm just tearing into another 750, so if it is to be rebored I could take the cylinders to the shop together. When I take them 3 or more sets at once, they sometimes give me a discount, depending on how busy they are or how fast I need them.