Dyna Coil

[skippyc]

I have just changed the crack-o-matic for a dyna brown. The crack-o-matic had been siliconed up but still had extra cracks hidden away, it was a lot worse than it looked.
The bike seemed to run alright before but today it ran so much better it revved out and pulled so much better and when I got it home it idled like a charm.

[montmil]

Eventually, all those Bosch Crack-Os will be replaced. Some day. Maybe.

[Bob_Roller]

I was surprised to see a thread started last week about a DYNA coil failing with not much in service time .

I had the OEM black and gray, crack-o-matic coil fail on my '81 R65, in '94, a little over 13 years and 25,000 miles on it .

This one didn't crack, the secondary circuit failed and had about 1000 ohms .

I replaced it with the upgraded red and black OEM coil .

That coil started to give me problems in 2006 with about 50,000 miles on it, had a hard cold starting issue .

The coil checked good with my multimeter, except my meter wasn't all that accurate for this application .

Took it to work and used a calibrated multimeter and found the primary circuit had a little under .7 ohms .

DYNA brown coil fixed the problem .

My other R65's have DYNA brown coils and my '87 Guzzi has two DYNA green 3 ohm coils, on a DYNA S aftermarket ignition system  .

From the postings of other members, there are a lot of other choices for coils for this application on our R65's, just need to fabricate an adapter for the coil(s) .

[Justin B.]

I don't know what it is with BMW and coils.  I've had to replace both upper coils in my R1150RTP - not cheap...

[Bob_Roller]

Are those the ' stick ' coils Justin

From what I've read on R1150R.net, the stick coils are problematic .

I've got the original coil on my '02 oilhead, looks like a later version of the coils for the R65's, single coil dual output .

14 years and 60,000 miles so far .

[Justin B.]

Bob, yeah, should be "stick it up BMW's ar$e" coils...  They are a coil-on-plug arrangement for the top plugs and the bottom plugs are fed by a conventional coil/plug wire setup.  The stock coils had "issues" so they came out with an "improved" coil but of course admitted no fault so the customer has to pay out the wazoo.

I was very tempted to try to figure out how to add a dual coil for the upper plugs...

[Barry]

Seems to me coils on modern vehicles have turned out to be inherently less reliable. They are all very low primary resistance/high current coils and have limited thermal capacity so for their very survival they rely on the dwell/current control of the ICU. Although I haven't had a modern coil fail in my car I know any number of people that have.  Contrast that with old bikes/cars where the coil lasted the lifetime of the vehicle.

As far as the high price of modern coils is concerned there really is no excuse for them being more expensive than old ones.

[tunnelrider]

my '87 Guzzi has two DYNA green 3 ohm coils

My R65 has a green coil, haven't looked at it closely enough to know if it's a Dyna sorry, but I presume it is on the mention of a 'green coil'.  Is this suitable on the R65 Bob?

Cheers.

[Barry]

Dyna green coils are 3 ohms primary resistance which as far as airheads are concerned makes them suitable for a points type ignition.

[Justin B.]

The Oilhead dual plug "stick coils" don't have very many fans.  My coils at least didn't outright fail but the idle quality was poor, I had to start off at a higher RPM/slip clutch than I like, and often would loose power at cruise.  All of these issues went away with new coils...  I bought the bike just shy of 30k on the clock and about 5k later the symptoms started and got increasingly worse.

My 4 wheel daily driver, 1957 Chevy, has a points ignition and a good ol' Blue-Streak coil.  Never fails...

[tunnelrider]

Dyna green coils are 3 ohms primary resistance which as far as airheads are concerned makes them suitable for a points type ignition.

Thanks Barry for replying on the green Dyna coils.  My green coil is indeed a Dyna coil, with an exposed laminate core. Do you know if these are suitable on the electronic ignition post '81 R65's?  I have to admit I've not had any ignition trouble in three years of ownership and starting cold is no problem, but I'm always keen on ideas to squeeze a bit more performance out of her.  It has always idled reasonably erratically (no matter how much fiddling has been done with the idle mix and throttle stop screws), never been able to achieve 'the ton' and has a fairly erratic tacho at highway speeds, over 5500rpm, but these may be just the way it is I guess.

I know I may be asking the wrong person as you have a different ignition set up and an R45 compared to an R65 so apologies in advance Barry if you don't know if the green Dyna coil is suitable for later models.

[montmil]

If memory serves, the Dyna green is recommended for points ignition while the Dyna brown, which to my eyes looks kinda orange, is used for those electronic bean can models.

[Barry]

Thanks Barry for replying on the green Dyna coils.My green coil is indeed a Dyna coil, with an exposed laminate core. Do you know if these are suitable on the electronic ignition post '81 R65's?I have to admit I've not had any ignition trouble in three years of ownership and starting cold is no problem, but I'm always keen on ideas to squeeze a bit more performance out of her.It has always idled reasonably erratically (no matter how much fiddling has been done with the idle mix and throttle stop screws), never been able to achieve 'the ton' and has a fairly erratic tacho at highway speeds, over 5500rpm, but these may be just the way it is I guess.

I know I may be asking the wrong person as you have a different ignition set up and an R45 compared to an R65 so apologies in advance Barry if you don't know if the green Dyna coil is suitable for later models.  

This is not about the fact it's a Dyna coil. Any 3 ohm coil would work with electronic ignition, the fact that it's 3 ohms instead of 1.5 ohms would not stop it working.  But you effectively have a points type coil triggered electronically so in terms of spark energy it will be similar to the earlier points ignition system.  And points systems on the early R45/65's work just fine so it's no surprise to hear yours runs OK

The question really is what advantage did electronic ignition give over points ignition. The simple answer is electronic ignition will have more in reserve than a points ignition but will not necessarily make the engine run better. There is nothing that you can tell from published power figures.  The ignition systems on R45's and R65's were identical so where it's possible to make a direct comparison, the R45 still made 35HP regardless of the type of ignition system. R65's were upped from 45HP to 50 HP for other reasons like larger valves at the same time electronic ignition was introduced so a direct comparison isn't possible but I'm sure there wouldn't have been a difference in power output.

As long as your engine runs well I wouldn't worry but there is a test you could do.  The spark plug gap spec is 24 - 28 thou.  If you found that the engine ran better with the plugs set at 24 thou than it did at 28 thou then that would indicate that spark energy is a limiting factor  and a change to a 1.5 ohm coil would be beneficial.

[Justin B.]

I'd be careful using a low resistance coil with points.  I tried this on a 240Z I had years ago.  I installed a high output coil that was specified for "electronic ignition" and although it started out working very well I got about 40 miles into a rally and the car died.  After farting around I discovered the points were not opening.  

I re-gapped them and got about another 30 miles and same thing.  I discovered the low resistance of the coil primary was causing so much current through the points the arm was getting so hot it was "bending."  I put the old coil back on when I got home and had no further problems.

[Tony Smith]

Dyna green coils are 3 ohms primary resistance which as far as airheads are concerned makes them suitable for a points type ignition.

And electronic ignition systems such as Boyer that were designed to replace the points (and advance retard) and leave the rest of the ignition train otherwise untouched.