Repro coils

[deltarider]

I might mount my stock TEC coils again. Measurements are OK. Primary around 4,5Ω, secundary around 14,8kΩ. Static test shows spark jumps 7mm easily. Is that enough for reliable results, or can you expect problem because of age and miles? Decades ago I have replaced them by Dyna coils (for the wrong reason). I estimate that before removal my oldies have served around 70.000 kms.
Anyone experience with repro coils? DS offers: DAFAB-300-003P. It doesn't state primary resistance.
https://www.davidsilverspares.co.uk/parts/by-part-number/partnumber_30501300003P/

[Bryanj]

As I said on the US site there seems to be a fixation about changing coils, all your numbers are good so why waste cash. the only thing that goes wrong with them is the leads and Ash has an excellent write up on how to repair those

[philward]

Plus one with Bryan's view on Ash's coil fix/lead degragation. Plus, I had 2 aftermarket coils fail (split due to overheating) - I used Ash's fix on 2 of my SOHC's with good results

[deltarider]

But... there's nothing wrong with the leads of my TECs. The question is: do correct measurements really tell it all? Here is why I ask this. The Dyna coils that I run now, also show perfect measurements, but when I connect the strobe to either the #1 or #4 lead, there's an occasional miss, where the coil 2+3 is constant and shows no misses. I have no idea if just one fouled plug in a wasted spark coil system, or just one HT lead that isn't connected a 100%, not noticed at first, can slowly terminate a coil? Will a miss on #1 always also show on #4, strobewise? What are your views on that?

[K2-K6]

Are you still running the Honda advance and retard unit?

If so, you could assemble it 180 degrees out (to make it wrong) then swap the two switching circuits to make it correct for firing. It would switch each coil with the opposite primary circuit and let you see if the miss stays in place or switched with the orientation.

[deltarider]

Are you still running the Honda advance and retard unit?

If so, you could assemble it 180 degrees out (to make it wrong) then swap the two switching circuits to make it correct for firing. It would switch each coil with the opposite primary circuit and let you see if the miss stays in place or switched with the orientation.

Do you mean to rule out a fault primary side?

[K2-K6]

Yes.

But that would also be true if you change to another coil too.

[AshimotoK0]

Your TEC measurements look fine. You need to assess if the PVC of the HT cable has gone rock hard and if there is any 'floppiness' as the cable emerges from the plastic coil body. You need to connect the meter across the HT leads again and flex the HT cables to see if the HT lead conductor wires have fatigued. This would be shown by getting a reading of around 15k Ohms. which goes then  open-circuit when the HT cable is flexed.
The TEC coil secondaries and primaries are very reliable in my experience, since the primary can handle prolonged current if the ignition is switched on and the points are closed with the engine not running. One problem with HT coils on CDi ignitions is that if you don't have  a suitable spark gap connected to the secondary, you can get internal HT 'flash-over' which can damage the insulation of the secondary.

Always beware of repro coils, that are intended for use with points, which have  a low primary resistance. The TEC coils will typically consume around 32 Watts if operated constantly without the engine running and the points closed. A coil with , say,  2.5 Ohm primaries will consume almost 60 Watts in the same situation .... the excess heat will probably fry the plastic etc and put excessive current through the points, which they were not designed for.

[deltarider]

OK, I sense I haven't communicated things well, so I choose a step by step approach now. As a plus, it may serve as some sort of tutorial. Feel free to add, correct or whatever.
I have two working sets of coils: the genuine TEC and a Dyna. Each set has its pro's and contra's. I have run both sets for some 70.000 kms, so I feel able to compare and have a verdict on them.
The TEC is a direct fit and comes with all its leads attached. The Dyna is a generic product and you need to buy a set of Dynatek HT leads, which adds to the costs. I've attached some pics to show the difference in dimensions. The Dyna is quite a bit bulkier.
The TECs are well up for the job, but you have to treat the leads with care to avoid repair later. Although this can be done, it will cost you time. Do not automatically assume some flimsiness you sense, where the leads exit the coils, is one and one with trouble. Mine always were like that and TEC even may have designed them so, to allow some wiggle room. As long as the wire inside is well connected, it will work. Why TEC didn't make them thus that you can replace the leads just as easy as you can the caps, is a mystery.
The Dynatek leads are very, very good. Both silicone caps and wires live forever. The Dyna will force you to run resistor plugs however; the caps have none. For the TECs it will be the NGK resistor caps that most of us are familiar with. The latter caps are easier to bring on/remove from the plugtops. Although the silicone Dyna caps are superior, they are not as easy to work as the NGK: not on a CB500/550 that is. Here's why. Dynatek terminals need that little nut that usually comes with sparkplugs. That's were things may go wrong. Our plugs, the #2 and #3 in particular, are in a difficult to reach spot and it is hard to detect if forsaid little nut is still fastened and has not come loose. I had this happen more than once. BTW, the plug wrench from the Honda toolkit can deal with both types of sparkplugs: with or without the little nut on top. For screwing in the plugs, I see no advantage in using a rubber tube to do the first turns. On the contrary; realise that such a rubber tube needs to be a 100% straight. I just press the plug firmly in the wrench from the Honda toolkit. The rubber inside the wrench's top, holds the plug firmly by its little nut and - guess what - the 18 mm hexagon then is exactly where it needs to be. Feels solid, works fine. But caution, every time you work plugs that have these little nuts on top, you must make sure, they are still firmly screwed on. Now for that you may need a tube (see pic), as the nut easily frees itself. Whether such looseness is enough to cause misfires, I dont know. The Dynatek wires need terminals for the coil side that you have to crimp on yourself. Although the terminals connect well in the coils towers, you must make sure, they went in all the way. The little black caps supplied with the Dynatek wires, shield the connection real well, better than the leads on the TEC, which remain somewhat exposed. However, years later you may find those little caps have become much harder to work. A hairdryer and some WD-40 can help. Realise that, even with those black caps correctly positioned, it's still possible to not have the terminals in all the way!  I always find it difficult to verify the terminals are 100% connected, even more so when you have used some WD-40 or silicone spray to slide caps over the lead. As a result things have become too slippery to exercise the needed force. With the coils bolted on the frame, there's very little room left for your fingers to manoevre and that is what makes it difficult.
Since the Dyna is a generic product, the connections primary side are not nicely sealed like on the TECs but are simply fastened by little screws. Although on the backside, they are in the open. An advantage is, you can use them for quick diagnoses like a V-drop test and it allowed me personally to have the feed wire for the transistor ignition connected to the PLUS side of one, so the module is, like the coils, controled by the killswitch.
Today I unscrewed the #1 and #4 plug. As expected both plugs were sooted black, #1 more than #4. Tomorrow I hope to find out more about what caused this. Is it still the #1 terminal that had gone rusty* last autumn and that I maybe have not cured enough? Will misfires at #1 eventually always cause misfires on #4? And is this because it is one circuit or is, by my neglect, by now the 1+4 coil already shot? Your opinions please.
* Never clean your HT leads with alcool. It will find its way into the plugcap and as alcool is hydroscopic... It would well explain why only terminal #1 became rusty, as I remember well the #1 lead has been the only one I have cleaned with alcool.   

[K2-K6]

For the little nut, ferrule? you can (not on the spark plug) tap it with a hammer on its end to shrink the thread pitch slightly.  This then has a lock nut effect to stop it coming loose.
Usually I tighten them with pliers too before putting plugs in on cars to prevent them from coming loose when running.

What is the material for the core on your Dyna leads?

[deltarider]

For the little nut, ferrule?

Ah, that's the word?

What is the material for the core on your Dyna leads?

Iron.
Late night I discovered the #1 terminal has NOT sat 100% on the ferrule. Once more WD-40 has tricked me! I remember I had had to use some WD-40 to slide the plugcap over the lead, after I had cleaned the rusty terminal. When I pressed the cap on the plug, I probably have not payed attention you must feel this kind of 'click' in your fingers, indicating it sits well over the ferrule. The WD-40 must have lubed the cap so well, that it has slided further than needed over the terminal and I, just by looking at the caps position, must have concluded the terminal was already fully on.
A warning. In my post last night I have already mentioned that the combination of WD-40 (or silicone spray for that matter) and the very little wiggle room that the CB500/550 offers your fingers there, is a tricky one. In that post it concerned the little black cap that seals the coils towers. Now it is clear it also can happen at the plugcaps. OK, so now I have to find out if it will only be a matter of connecting things well again, or that the bad connection in the meanwhile has damaged the coil.
 

[K2-K6]

That type can be slightly difficult to fit and get the connection fully into place.

I use that type on a car engine but with silicone plus carbon core (many don't like that type of core but I find them really good and long lasting) and because they are inherently bendy, have to be careful when installing onto the plug top. I do use silicone grease inside the cap as it makes it much easier to push the rubber seal down along the spark plug ceramic area, makes them virtually impervious to water though.

The coils are usually pretty tough, so doubt it would have damaged them being slightly off connection. Just would have given more resistance as the spark will usually cross that gap leaving a carbon trace mark where it's jumped.

[deltarider]

OK, two things I hate: loose ends and doing things twice unnecessarily. So see: http://forums.sohc4.net/index.php?topic=187698.0