1973 Yamaha DT3 250 Spark Plug Cap

[YamadudeXS650C]

I'm in the midst of a resto of my recently-purchased DT3 250.

I noticed today that the spark plug (B8ES) has the terminal screwed onto the threaded stud (by the PO).
Kinda surprised me. The plug cap appears to be stock, and I sorta remember this style of cap from my 1974 DT360 I owned years ago.

The cap fits rather snugly on a plug whether or not it has the terminal on the threaded stud, but the plug does fit deeper into the cap when the terminal is off of the plug:

Here is the shallower fit when the terminal is on the plug:

Here is the inside of the cap:

When I put the cap on the plug with the bare threaded stud, I don't hear/feel the expected metal-to-metal contact.
I'd like to try starting it up and checking the strength of the spark with and without the plug terminal, but its a snowstorm outside, and the bike is in my indoor workroom.

Given the evidence, however, I'm thinking that cap is a non-resistor OEM item which is supposed to fit on a plug with no terminal, just a bare threaded stud.

Therefore, replace it with a LZFH.

Neither my Clymer nor a web search gave me any related info.
Opinions?

 

[Downeaster]

I don't think resistor or non-resistor has anything to do with the cap-to-plug fit.

It's about the style of socket in the cap. In my experience, the style intended for bare threads on the plug has a springy wire as the connection. The ones that fit over the nut on the plug are generally just a round metal cup.

If you're not getting solid contact with the terminal off, leave it on.

 

[59Tebo]

Could it have been made to fit both?

 

[YamadudeXS650C]

I don't think resistor or non-resistor has anything to do with the cap-to-plug fit.

It's about the style of socket in the cap. In my experience, the style intended for bare threads on the plug has a springy wire as the connection. The ones that fit over the nut on the plug are generally just a round metal cup.

If you're not getting solid contact with the terminal off, leave it on.

Resistor vs. Non-resistor comes into play when I replace the cap.
I'm inclined to replace cuz it seems to be rusty inside where the contact portion sits.

 

[YamadudeXS650C]

I'm inclined to replace the cap with the "stud" style cuz the modern ones seem to make a tighter, more definite contact.
Further, I once had a terminal loosen up, despite having tightened it well. I recall someone suggesting loctiting the terminal, but that would seem to possibly interfere with electrical conductivity.

 

[YamadudeXS650C]

Could it have been made to fit both?

INteresting possibility, Jerry.