After some help from the brain trust....but you lot will do instead. Replaced my spark plugs a few weeks ago on my 83 basic and have found that, now on two occasions, the lead had wriggled itself off the plug. I have the original metal capped plug leads and the middle two plugs are the escapees. Can I squeeze the plug connector is some way to have a tighter grip on the plug? I suspect that over the years the grip has lessened. The routing of the plug leads has been changed now to eliminate one plug lead moving another because of vibrations.

Cut 4 pieces of fuel hose about 1 inch long and put them over the tang you grab with pliers that way when you screw the cover on the caps cant move.
They also have a wire spring clip around the base of the cap make sure it is in place and the cap is pushed in tightly, they can be very tight.

Thanks Rick, will do tomorrow after the bike cools off. All was good until I changed the plugs.

Amazing what you can see and do when the engine is cold and you are not on the side of the road with traffic screaming past you. The small screw on tip of the spark plug , on the lead end, had un screwed itself. When I pulled the lead off and bent down and had a good look at the spark plug and then looked into the lead cap I realised what the problem was.
I then checked the rest of togs, all good.

NGK call it a 'terminal nut' Stan. Glad you found the problem and it was a simple fix.

Cheers

On my bike the terminal nut is the bloke who sits on it, or should it be Knut.

While NGK makes great plugs, their application guide/cross reference sucks when it comes to matching the plugs for the Brick.

There is a suffix on the plug number that adds the terminal nut.  Why that isn't included in their application guide is a mystery to me.   If I am not mistaken the correct numbers for bricks are D7EB and DR7EB. 

http://www.ebay.com/itm/Spark-Plug-NGK-DR7EB-/252489710858?hash=item3ac98f3d0a:g:ixkAAOSwbsBXpQL8

The translation is as follows:

D = 12mm thread
R = Resistor type plug for non resistor wires(this letter is omitted for non-resistor plugs)
7 = heat range(lower numbers mean hotter plugs, a 6 heat range may be useful when dealing with oil fouling)
E = 19mm thread reach
B = integral terminal(solid nut) 

The last letter(the B) is what is the correct designation for brick plug wires.  Why the A(for threaded terminal) is shown everywhere is puzzling.

Here is a link to the NGK part number decoder:

https://www.ngksparkplugs.com/assets/design_symbols_plugs.pdf

The plugs I bought did not have the terminal nuts on them. I had to remove them from the previous plugs. Apparently NGK only supplies the nutless ones as standard procedure.

Per my earlier post, next time you buy plugs try asking for the D7EB.

Thanks for that info Point-Seven-Five. I searched the NGK site and didn't see that.

For Aussie members.... you can buy DR7EB and I think D7EB off the SparesBox site at the moment for under $5. They have specials on atm on Castrol and Nulon oils as well as Ryco Z418 filters. Free freight for orders over $50

NGK Spark Plug Resistor DR7EB | Sparesbox

Update:  NGK tech rep has just advised me that D7EB is no longer available.  However, it is OK to substitute the DR7EB in it's place.

That shows just how smart the tech Rep is. That can lead to serious overheating of the coils and ultimate early failure.

What Rick says. Using an 'R' (resistor) rated plug will double the resistance seen by the coils.

I'll bet you that there are thousands of K100s out there with resistor plugs and the original cables who have no problems at all.

The 1984 K100 Rider's Handbook and the 1987 BMW K75/K100 Repair Manual specify non-resistor plugs. The 1988 BMW K1/K100RS Repair Manual specifies resistor plugs. Both the 1994 and 1995 K75 Rider's Handbook specify resistor plugs.

My K75 came with resistor plugs and OEM plug wires with resistor caps. I've used resistor plugs as replacements. Electrode color at replacement is tan/grey. Performance is acceptable. Fuel mileage averages 50mpg.

Crazy Frog asserts in a past post about K-bike spark plug and wire resistance that running without sufficient resistance will damage the coils. Nothing is mentioned about damaging effects of resistance at ±10k ohm levels. 

R. Fleisher, in his comprehensive article on BMW bike ignition systems, asserts that excess resistance in the amounts being discussed here with Classic K-bikes might have slight effect on both mileage and performance when plugs are at a marginal state. Resistance in the caps seems more effective for performance than resistance in the plugs, as I read his statements. Resistance in both may not be unnecessary, but he acknowledges that in some K-bikes both resistance caps and resistance plugs have been factory-installed together—the theory being those resistance levels slow electrode erosion while still allowing effective spark in the lean fuel mixture used by these bikes. Nowhere in his article did I read warning about excess resistance effects at these levels being damaging to the coils.

The exponents posting in this thread on both sides of this discussion are experienced riders and wrenchers. Personal experience will usually carry the day. What I'd like to read here is a forum member's explanation of why resistance of 6K ohm will not damage these coils but resistance of 10K–12K ohms will damage them. From what have read so far, these coils might handle resistance levels like that with no significant effect. 

My experience is that my bike seems to run ok with the current setup.

The 5k of the plug is virtually insignificant when you consider that it is in series with the resistance of a 0.7mm air gap at the firing electrode which has a resistance prior to firing on the order of millions of ohms.  Even after the ionization of the air in the gap by the spark this gap resistance still dwarfs the 5k of the plug.

The only downside of the plug's resistance is that it will absorb a tiny bit of the spark energy provided by the coil, but again, the value is so low in comparison to the air gap that the energy loss is insignificant. 

On the other hand, the minuscule decrease in spark current which results from the slight increase in circuit resistance will actually REDUCE the internal heating of the coil.  The reduction is nearly zero, but still, it is a reduction.

Point-Seven-five wrote:The 5k of the plug is virtually insignificant when you consider . . .

It would seem that adding another 7K ohms resistance into the system would not be significant either—based on your view, Bob T's view and my experience, Point-Seven-five—but that additional resistance is viewed by others here as an overload on the coils. Understanding how that conclusion is reached might helpful to some of us.

Because of the rapidly changing current and voltage of both primary and secondary the situation must be regarded as A/C not D/C and so a very different set of formulae are used and the load (plug and plug lead) MUST be matched in IMPEDANCE not resistance to the source of the power generation (coil secondary winding) to get maximum power transmission.
When the impedance of load and source become mismatched by even a small percentage you can and usually do get big power reflections and so heat build up which can rapidly destroy the insulation between windings of the secondary and primary windings of the coil.
QED

RicK G wrote:Because of the rapidly changing current and voltage of both primary and secondary the situation must be regarded as A/C not D/C and so a very different set of formulae are used and the load (plug and plug lead) MUST be matched in IMPEDANCE not resistance to the source of the power generation (coil secondary winding) to get maximum power transmission.

The QED is a nice touch.  

If this difference in impedance might result in the breakdown of the coils, how rapidly does it occur? 50k miles? Less? More? What is governing the rate of breakdown of the coils? Why are ignition components like spark plugs and plug wires not characterized by their impedance rather than their resistance when marketed?

That will vary quite a bit and will depend on the climate but 50K would be a median point. Bikes I have seen it happen to are usually well past warranty so does not concern the manufacturers and truth be known probably suits them.
Impedance is usually calculated and resistance can be measured easily with a meter in a static situation.  Because of the rapidly changing nature A/C can have the calculated impedance will vary depending on frequency and even wave form can have some effect.

Impedance implies phase angle resulting from the relationship of resistance to reactance specifically the inductance of the coil.   As I mentioned previously, the resistance of the air gap is so high that the addition of another 5k in the form of a resistor plug has very little effect on the impedance. 

According to the NGK tech rep the only place where resistor plugs are not recommended is in magneto systems.   While the rep did not mention the reason, I suspect that it may be due to the lower spark voltage available in those systems compared to modern electronic ignition systems.

RicK G wrote:That will vary quite a bit and will depend on the climate but 50K would be a median point. Bikes I have seen it happen to are usually well past warranty so does not concern the manufacturers and truth be known probably suits them.

Shades of Vance Packard! 

The implication is that the specs encouraging the use of resistor plugs when resistor cap leads are supplied as stock might be part of a scheme to promote an income stream for dealers in service, parts and maybe even for sales of new bikes to people who are satisfied that their former bike had a median life of just 50K miles/kilometers. 

That's a long view, all right. Almost as long as VW's diesel emissions scheme but not nearly as serpentine.

My bike is past the median but I pledge to continue using resistor plugs until the system is damaged, then post the mileage here—just to help increase the knowledge base. After that, I'll be selling or parting out the bike to fund a battered KLR650, or maybe even a postie. There are a couple of nice ones over in New Hampshire right now.