In the course of preping my K1100LT for the coming riding season, I'm changing the spark plugs.  I pulled the Bosch XR5DC and bought NGKs.  The parts guy said I needed DR7EA.  When I went to install them, I discovered they do not have the round caps on the wire end, and the caps are not included in the boxes.  This is the first time I've bought spark plugs that do not have those rounded tips.  I went to pull them off of the Bosch plugs but found they are apparently integral to the plug; I wasn't able to remove them.  I saved the day by finding some tips on old plugs I'd horded away ages ago.  They went on the new NGK plugs without any issue.  I surmise the tip's thread size is common to all spark plug brands.
So, if you mean to use NGKs in your K1100, it's best to verify they have the rounded tips for the secondary ignition wire ends.

That's what happens when you buy NGKs. I save all the terminal nuts I find. Like a squirrel.

Never figured out why NGK doesn't include them.  Autolite and other brands do.

I just gave up a few years ago and bought 25 extras on Ebay so I have a stash of them on hand.  Only seller I could find was in the UK. $4 +$2 shipping.

https://www.ebay.com/itm//322978987996

Your local mower shop used to be a good source of spark plug nuts. They used to have a bucket full of them $5.00 for a good handful. The guy I used to get them off has now gone so now I have to find another friendly mower shop.
Regards Martin.

I called U.S. NGK technical support in Michigan and asked the technician if he would send me a dozen.  Had them 2 days later.

Maybe if everyone hit them up for those nuts they'll start including them again.

Point-Seven-five wrote:I called U.S. NGK technical support in Michigan and asked the technician if he would send me a dozen.  Had them 2 days later.

Maybe if everyone hit them up for those nuts they'll start including them again.

Good idea.

Still silly of them not to include them.  They should come with the plugs so you don't have to call and wait two days just to install spark plugs.

As it was explained to me, very few automotive engines use the "old" style plug wire terminals anymore, so there was little need for the nuts.  As a result, the bean counters had them deleted.  No problem getting the nuts, just ask.

I've used NGK for about 50 years now.  That little bit of nuisance is worth it to me.  One call and I'm set for as long as I run my bricks.