If you go to realoem.com and enter the last 7 digits of you vin# you'll be able to search parts for your model.
Resistor plugs XR5DC are specified
NKG also specify resistor plugs DR7EA
Looks like you were right but if you want to keep the resistor HT leads you have, just use non-resistor plugs like D7EA

mr grumpy wrote: It is possible I suppose that the leads are not the originals, which may have been replaced with the earlier 8v type.

The 8V and 16V have different coils, with different primary resistance and
the connectors is different both on LT and HT side....so the HT leads can't be mixed.

Both 8V and 16V HT leads have the same resistance, in addition the 16V have
resistor spark plugs...due to the lower primary resistance in the coils.

The non resistive leads probably wont fit the coils correctly. The 16v also has different coils which are not interchangeable with the 8v ignition system.
The 8v coils have a spade terminal and the 16v coils a 2 pin plug moulded into the coil. The 16v coil also has very different HT terminals to the 8v. I would say that they were designed so that swapping bits around was not easy.
The 16v coil has a much lower primary resistance than the 8v and ignition damage could occur if the incorrect coils are used.

My mistake. I thought the leads/SPs were swapable. I didn't realise there was such a difference in the way the coils are designed. Is there a reason for this?

Is there a reason for this?
AFAIK it is just so they cant be mixed easily. If you look down inside the coil towers you can see a short projection that clips into or onto the lead end.
If you mix them up the mismatch in impedance can cause power reflections into the coil and ignition transistors and this causes heat build ups then "Fizz bang no work".

So what would be the likely effect, positive or negative, of using the non-resistive plugs in the 16v engine?

Negative, any mismatch of components in any electrical system is not good but in this case it could be fatal to the ICU and at the very least the spark produced will be far less than optimal.

Thank you for clarifying that, Rick, I shall get the DR7EAs.

RicK G wrote:The non resistive leads probably wont fit the coils correctly.

When you say non resistive leads, you mean aftermarket leads I would presume?

Inge K. wrote:

RicK G wrote:The non resistive leads probably wont fit the coils correctly.

When you say non resistive leads, you mean aftermarket leads I would presume?

The leads that are designed to be used with the non resistive plugs and coils of the 8v system. I think my brain was in front of my typing for a change   Mind I am a slow typist.

My K1100 experience if you do not mind...

As concerns the total HT line resistance, I mean between coil and spark plug central electrode, it is over 140 000 km that I ride with 4 lines of 7 kohm each. No problem at all except that:
a) the engine does not heat as much as before, as most K1100s with 12 kohm lines are famous for doing. This is probably the result of better sparks.
b) the engine is definitely smoother
c) the fuel consumption is probably lower. But as the engine is more pleasant, I have more tendency to play with it.... For sure it does not consume more. For many years I was - because there is another point to follow - around an average of 5 to 5.2 liters per 100 km, riding around 4000 rpm. Before changing those lines I was rather around 5.4.But the synchro was possibly not ideal then.

The removal of 5kohm in the HT line can be made two ways:
a) using non resistive spark plugs whilst keeping the original BMW wires (wires which have 2k on the coil side and 5k on the plug cover side)
b) keeping the resistive spark plugs (5 kohm) and changing the wires for less resistive ones. That is the solution I preferred because most "modern" spark plugs are resistive, and as it gives the occasion of renewing the HT wires, which are surely not eternal. I purchased mine in UK, in a company called BSK Speedworks, which is obviously in love with our Ks.

For a long time I used NGK spark plugs, mainly DR7EA9, which come without the nipple. So for years I dismantled the old nipples and fitted them on the new plugs. Aluminium against steel. Recently I was faced to ignition problems. I noticed that when I dismantled my spark plugs their nipples were loose. I fitted new NGK spark plugs, with nipples well tightened, The problems were solved... for 2000 km. And again the nipples were loose.
I therefore decided to get rid of those spark plugs needing an apparently wearing accessory to fit the HT lines. In the technical manual it is stated that the engine should be fitted with spark plugs with a gap of 0.5 to .0.7mm. In Bosch it is the XR5DC plugs which are suggested. Those plugs have nipples solid with the central electrode. Impossible to get loose.

Exactly what I wish.

Looking for XR5DC spark plugs, I found two models of them. Same name but not same specs.... One is the XR5DC referenced 0.242.145.500. The other one is the XR5DC referenced 0.242.145.516. Only one is convenient: the one with the reference ending by 500. That one has a gap of 0.6mm. The other one has a gap of 0.9mm, i.e. 28 to 80% more than stipulated by the engine designer, who has probably good reasons for asking for a gap of 0.5 to 0.7 mm. Probably related to the coils behaviour.

I installed those XR5DC with a reference ending by 500 and... my bike now works like in a dream.  So far I emptied 3 tanks and my fuel consumption has been between 4.7 and 4.9 litres per 100 km.

As I am the kind of person who easily believes what experts say, I took as granted that the NGK DR7EA were excellent plugs for our K1100s and I fitted them exactly as they came off their box. I.e. with a 0.9 mm gap... I just checked that both electrodes were parallel to each other, as their designer has designed them for a uniform sparks distribution. In my mind, when you change a gap you change the electrodes geometry. The correct gap is then just towards one edge of the central electrode, which implies that the spark is always at the same narrowest place. That should imply faster wear. This is less true for spark plus with a very thin central electrode. These do not appear suitable for the Ks anyway. They are told to be eventually convenient for the 2 valve Ks, but as they are necessariy resistive, there is something strange...

If Bosch make two types of XR5DC it is probably because a XR5DC with a 0.9 mm gap reduced to 0.6 does not work as well as a true 0.6mm gaped one.

To be complete and fair, I must confess that in addition to changing the spark plugs for some with the proper gap, I also changed the HT lines for new ones. One set costs the price of one cheap tyre and I estimate that after 10 years they have the right to retire.

This is just my experience. I surely do not mean that it is the only good one!