Topic: cb550k Ignition Coils

[wizzy]

Happy New year to all,

    My stock ignition coils are shot, and I have been searching for a decent pair on line, (bikebarn.com) and misc. others. I can find alot for the 750k and 750 super sport but have not been able to find a set for the 550?  I still have the points system on my bike and will upgrade to the dyna-s system in the next couple of months. Does anyone have a good site for buying new / used coils, my next question is that some coils are sold as 3ohm-5ohm coils, what is going to be the best for the set up i have now, verses the the set up that will compliment the electric ignition to replace the points. thanks for your time.
"Wizzy"

[TwoTired]

While 3 ohm coils provide a higher spark potential (advantageous during periods of low battery voltage), they also draw nearly twice the power from the bike's electrical system.  Since the 550 does not make enough power to charge the battery at idle RPM, this means you will deplete the battery quicker with 3 ohm coils.  If your riding regime includes city stop and go traffic, you can expect charging issues.  If you mostly ride/operate where the RPM's are above 3000, then you may be able to tolerate the increased power draw.  Also, you can expect your points to wear out faster, too, as they will heat faster with the increased current demands.

The stock coils from Honda are a very good reliable design hampered with the fact that the ignition leads are not separately replaceable.  When these crack and break, then the coils are often replaced for that reason.  I've also seen them require replacement after being caressed by a hatchet. 

Another advantage to 3 ohm coils is that you can widen the spark plug electrode gap for a more efficient burn, and 3 ohm coils have the capacity to fire the plugs reliably.  In the 550 ignition design, the spark gap determines the voltage at the time of the spark jump.  As long as the coils can develop this voltage, the ohm rating is unimportant.

Contrary to popular belief, higher spark voltage, by itself, does NOT equate to more power output of the engine.  However, if other engine design mods are made (such as higher compression ratios or increased spark gap), then higher spark potential may be required to fully enable those mods.

According to the shop manual, 750 coils are different than 550 coils.  750 coils have 380 turn primaries and 15,000 turn secondaries.  Whereas 550 coils have 420 turn primaries and 13,000 turn secondaries.  I've not measured them side by side.  But, this difference should certainly make the 550 coils read a higher primary resistance than the 750 coils, and draw less power than a the stock 750 coils.

The other ignition difference, 750 and 550, are the spark plug caps.  750's use 5K ohm caps and all the 550's I have came with 10K ohm caps.  However, I am not certain this is directly related to the coil selection, the spark plug selection, or a combination of the two factors.

I'm certain you will get reports of using coils from just about any source (with no problems perceived) on the 550.  It's your time and money to spend as your wish.  But, I am wondering how you determined your existing coils are bad?

Cheers,

[Ichiban 4]

Wizzy..

Dyna also sells some good coil sets to go with their S ignitions.  So..if you're planning on getting the Dyna S..check out their coils to go with their ignitions.

I was really impressed by Lloyd's (Two-tyred) breakdown on the differences between the 550 and 750 coils, et al..thanks for that Lloyd!

I have a Dyna S on my 550 Jason..it's a noticeable upgrade from the old points set-up.  If you can swing it..I'd suggest just getting the Dyna S now..get the recommended coil set from Dyna to compliment.

But as Lloyd pointed out..the 550's alternator doesn't put out enough juice to keep the system charging @ low RPM's.  So 3 ohm coils may either require that you keep your engine revved when stopped..and/or disconnect the lights from running during the day..which may help (think you are making your '77K into a cafe'..right?).  Reason I mention this..is because Dyna offers both 3 and 5 ohm coils to fit the 550's I believe.

Ja..Ichiban

[wizzy]

to anwser the questions about why I need new coils is that i am testing and getting a blinking light signal with a test light while testing the blue and yellow while jumping the starter siloniod. but both coils are not producing spark, i bought the bike from the 1st owner since 1977, and it has been parked since 1982. i am getting power and signal to the coils from the points, but no spark out of any of the wires.

[TwoTired]

to anwser the questions about why I need new coils is that i am testing and getting a blinking light signal with a test light while testing the blue and yellow while jumping the starter siloniod. but both coils are not producing spark, i bought the bike from the 1st owner since 1977, and it has been parked since 1982. i am getting power and signal to the coils from the points, but no spark out of any of the wires.

The points do not provide power to the coils.  They provide a ground path to the coils (blue and yellow) so they can store energy when the points are closed.  The coils are powered by the 12V black/white wire from the Stop-Run-Stop switch.  That switch gets its power from the black wires coming from the main key switch.

If your test light is powered from a 12 v source, it is blinking because the points are opening and closing and providing a ground path, on an off.
If your light is connected to ground then it is blinking because 12V is passing through the coil primary.

The FAQ has a coil test procedure.  I do not know how you are testing for spark.  But, both ign. leads of the paired output of each coil need to be near engine ground for them to have a current path when the coil dumps its stored energy (as points open).  Do not try to test the leads individually as you can with many autos.  Further, spark plugs can foul/fail to prevent a spark jump.

It is extremely rare that both coils would fail at the same time.  In fact, it is rare that either coil would fail, for that matter, though possible.  However, I don't think you have yet proven your current coils are, indeed, bad.  Check the position of the stop-run-stop switch.  And, verify that 12 V is indeed going to the coils.  Also, verify that you are getting more than 10V to the coils.  A low/weak battery won't put enough energy into the coils to jump the spark gap predictably.

Cheers,

[wizzy]

black  w/white stripe wire from both coils show "hot" when the switch in in the run position with ignition on. yellow getting signal. blue getting signal. don't know about the green ground with the eyelet. seems clean and free of debree.  still to spark out of plugs, there brand new ngk and cannot see spark from any of them.

[chippyfive50]

I have the DYNA s and the DYNA 5ohm coils and silicone wires. The difference is UNREAL.  Easy start...I kick start it for fun now..1 kick.
I am going to put them on my 750 next.

[wizzy]

awesome I can't wait to get some on order

[wizzy]

Does any else have a technique to pass on to test ignition coils.
mine are getting power from the black/white wire, they are getting a signal from yellow/blue from points but i still get no spark at the plugs. i have had replys that both coils don't go bad at the same time, just remember i bought the bike not running 1st owner had it sitting around since 1982. is there some other electrical componit i am not checking. the kill/run switch does in deed send power and cut power to the coils like it should. any more help would be super awesome. i have my battery on a battery buddy trickle charger so it should not be a low celled battery.
thanks to all
"wizzy"

[TwoTired]

- Work on one coil at a time, either 1-4 or 2-3 coil.
- Verify the yellow wire from the points actually connects to the 2-3 coil.
- Verify the Blue wire from the points actually connects to the 1-4 coil.
- Remove the spark plug caps (unscrew) from the ends of both ignition leads.
- Examine the ignition leads for insulation cracks or breaks, and that the unscrewed ends have a clean wire contact for the plug cap screw. 
- Test for continuity between the two ignition leads. There needs to be continuity, as in an electrical path or a failure is indicated.
- Tape or otherwise hold the ends of the ignition leads near each other or 1/8 inch away from the cylinder block.
- Position the engine crankshaft so that the points for the coil you are testing are open.
- Turn on key switch and place ignition cutoff in the run position.
- using a jumper wire other metal object short or jumper the two point contact surfaces together.  (Insulate yourself from the apparatus, as back EMF can zap you.)
- When you remove the jumper or short from the points, you should get a spark jump from the ignition wire leads.

- If no spark, remove the condenser lead only from the points, reconnect the yellow or blue wire, and repeat test.  (A leaky condenser can shunt away voltage faster than it can rise to spark the plugs.)

- If you now get spark, replace the condensers.
- If you still get no spark and you are certain the coils are getting the full 12V across the colored lead and the B/W from a good, charged battery, then replace your coils.

Cheers,

[wizzy]

Thanks for leading me in the right direction.
you are a true help to this site.
Thanks a-million
"wizzy"

[dusterdude]

lloyd,since you mentioned opening up the plug gap with 3 ohm coils,do you have a recommendation for what the gap could be opened up to on a 750?thanks

[TwoTired]

lloyd,since you mentioned opening up the plug gap with 3 ohm coils,do you have a recommendation for what the gap could be opened up to on a 750?thanks

Sounds like such a simple question, doesn't it?  My seat of the pants answer is about  0.035 inch.

Assumptions:
- Stock compression ratio.
- Full battery voltage getting to coils. (especially during electric starting)
- The three ohm coil selected has a turns ratio greater than the original five ohm coil (it should).
- 5K ohm plug cap resistance.

Note that if you are still using points, they may wear faster, as the coils are forced to develop higher voltage to jump the spark gap.  This will take more energy from the electrical system, which the points control.  More power = more heat.

Another caveate is that I do not have any 3 ohm coils to test.  I am basing my recommendations on theory and knowledge of ignition systems, in general.

What to expect: 
Better fuel economy.
If you are jetted on the rich side of Stoichiometric (should be the case), you should achieve a little more power output from the more complete burn.
Spark plug deposits should lighten somewhat.
Start up may be less vigorous. One of the reported benefits of 3 ohm coils is faster start up.  This is due in part to the higher voltage capability of the coil when provided with low voltage during starter motor cranking.  However, with the increased spark gap, the voltage REQUIREMENTS are also increased.  If your bike suffers from low delivered voltage to the coils, the vigorous staring may no longer be realized.

Risks:
I suppose there is some risk that the coils may not be able to deliver the higher voltage at higher frequencies (read high RPM), since I don't know anything about the magnetic core design.   When plugs and points are in new condition, there is less likely to be an issue.  However, as they age, if high RPM misses are detected, then back off the spark gap some or renew the worn components.

Hope this helps,

[OldSchool_IsCool]

To help save your points, consider HondaMan's ignition module.  Last I knew, he had a model for 3-ohm coils. 

Nice think about HondaMan's module is, if it fails, you still have standard points that will let you ride home.  Should a Dyna module fail, you're looking for a trailer to get your scoot to the shop.

[Deltarider]

Wizzy,

First make sure your coils are really gone. For the original TEC FL703 (Toyo Denso) coils, Honda’s Shop Manual CB500-550 (p. 89) will show you how to check for continuity.
Primary coils should read 4,5 - 5 Ω, secundary coils (via HT leads, caps removed): 14-15 kΩ . Ultimate test however is to be performed on a testbench, which few of us have.

Aftermarket suppliers generally advise 5 kΩ plugcaps. That is more than enough for noise suppressing. I’m surprised Two Tired has 10 kΩ caps on his bikes. I would like to know whether he measured these caps separate or attached to the coils. Ten kΩ is considerable in a dual output coil setup. Plugcaps (and plugs) may vary to meet demands in various markets. I have not discovered what value Honda originally intended, but I would not be surprised if the original metal shielded caps showed resistances between 2 and 3 kΩ or even as low as 1kΩ. By the way, NGK still has 1kΩ plugcaps in their program (SD01F and XD01F respectively).

Years ago I swapped my OEM coils for the 3 Ω Dyna coils. Can’t say that I’m impressed. In spite of it’s high price, one already gave up after 30000 kms. The original TEC coils served me over 70.000 kms and are still O.K. On the other hand, HT leads in OEM coils are not impressive either. But that can be helped. Some people are clever in removing old leads (Dremel) and replace them by new cables using little copper caps. Let’s move to the other end. Every time you pull the plugcap, there is a good chance leads can become loose. Removing the cap, cutting a bit of the end of the cable, screwing the cap back on can help, but eventually you’ll end up with a short lead. When it becomes to short – ta-ta-ra-ta -, you can buy he NGK J-1 cable coupler.

Like coils, condensers can live very long indeed and like coils chances are little they brake down at the same time. With it's wire detached from the breakerpoint you could check their isolation. When resistance is above 5 kΩ isolation is good, between 1 and 5 kΩ satisfactory and below 1kΩ it is bad.
IMO most ignition related problems have their origine in deteriorated connections and/or fouled plugs. Do not expect any increase in HP from whatever electronic device. Apart from Hondaman’s ignitionbox and the one I assembled myself for a few bucks, I find them all highly overpriced. There is a lot of stuff you can sell people with ‘mysteries’ like electricity and magnetism.