I was wondering if anybody had adapted a Dynatek Coil for the K100's. They make 3 different Ohm varieties and it would seem likely that the 3 ohm version should work. I used a Dynatek Coil to replace the stock coil on my 95 R100RT and it worked fine. Both the R & K have electronic ignition so you have to be careful in which Ohm version you use. The mounting could be a bit of an issue on a K bike, because of the way the stock one's are located and mounted.

Just searching for options as my old 86 model still has the grey coils, they haven't caused any issues, but they are getting up there in years. The new stock coils from BMW are really expensive up here and I would like to go another route if possible.

the grey coils will do just fine ....as long as you look after the whole system  from plug to coil ...far too often we see things missing off the plugs , broken cables  with near infinite resistance etc ,,, maintenance is the key to them lasting longer than ever expected .....



i would certainly think that any coil should work above 2 ohms , but again think of where and how its fitted , will road sludge adhere to them in that mounted location , will wetnes penetrate the coil output secondary terminals , and all that sort of stuff .

good luck

I agree, electrical & ignition systems do need to be looked after and likely the 3 ohm coil would work fine. I would mount it in the same location as the stock coil, just would have to make up a bracket or mount it to the existing bracket with some modifications.

Posted for information purposes. I checked the primary resistance/inductance ( take your pick ) of the grey coils on my K100 and both register 2.3 ohms. I'm not sure what they are supposed to be as checking the BMW manual or a Clymer doesn't give you any values. I can only go with what others have posted. I may start a new post just to see what are the results of the different coils.

I see lots of pictures of the early K bikes with black coils and wonder if the black where the first generation, then the grey and finally the ones with the red tips being the last version. The first generation K bike, up until they went to the 4 v model no doubt had its roots strongly in the automotive world when it came to ignition coils etc.

An interesting side note is the stock coils on my 95 R100RT register .7 ohms primary and that was with the stock electronic ignition. Those years of airheads used a very similar ignition module as the K100 4v and up used.

Hi cycleman, did you end up using some of these coils? If so, how did it go?

Cheers,
Chris

I sent a few emails off to dynatek, asking about the DC1-1 (Green cylindrical coils) and the DC2-1 (miniature coils). Both are available with 3 Ohm primary resistance. responses below:

If considering the DC1-2 coils, just be sure the ignition system in use was designed for a 3.0 ohm coil, but most importantly, the ignition has an active dwell control function, or the ability to charge the coil to exactly what it needs for the next spark cycle. An ignition with a fixed dwell time will not work and damage to the coil and/or ignition may result.

If you need two (2) dual output coils and the ignition is not a dwell controlled unit, the DC1-1 coil set would work well, even if it is a dwell controlled ignition.
We also offer a 2.2 ohm coil set, part number DC4-1, but these may have a bit too low primary resistance.
If you have access to a factory service manual, see what the OEM coil specifications should be, and pick the above part number which is closest to the OEM coil spec for the best performance and reliability.

So I guess the next question is, does the K100 have active or fixed dwell control?

Cheers,
Chris

short answer ,,,  yes 

all controlled by the ignition ecu ,   so much stuff in there , in such a small package

ok cool thanks, I might order some bits and have a go then. The miniature version should easily fit in the stock location and retain the coil cover. With the DC1-1 coils that was going to be more challenging.

mynameisrodney wrote:Hi cycleman, did you end up using some of these coils? If so, how did it go?

Cheers,
Chris

No I haven't. My old coils where within specs, so I changed the plug wires and put in new spark plugs. I wasn't having any issues, just concerned about the coils age.

In response to the latest posts. The K100 depending on years changed the ECU and the coils, so you have to be careful which coils you get.

Do you just mean that the resistance changed or was there also a change with dwell control?

Mine is a 1986 K100RS with the all grey coils.

mynameisrodney wrote:Do you just mean that the resistance changed or was there also a change with dwell control?

Mine is a 1986 K100RS with the all grey coils.

Your bike should have the same coils as I have. They changed the coil resistance on latter models and also made some changes to the ignition module, starting with the 4 valve models in 89. I believe all the 2 valve stock models would be the same as our bikes, but I could be wrong. Somebody more knowledgeable than I will chim in eventually.