What's this part - is it needed?

[BINOVC]

My Iso Grip came unglued today.  Inside I found this throttle tube end-cap, looks like it "used to be" threaded in.  The threads are no longer functional on the end-cap.  Should I glue it together, or put it back like I found it (the iso grip will keep it in place), or just leave it off?
https://www.flickr.com/photos/cocojen/42695192255/in/dateposted-public/

[Jess from VA]

Glue it back on and slide the grip over it.  With some extra glue inside the grips.

The thing is, the Kury Iso Grips (specific for Valk) are extra long (6 1/4"), from the standard 5 3/4" universals. (This lets you add a throttle boss on the outside end that does not interfere with normal riding, esp with bigger hands)

Those spacers are provided to add a stiffener for an otherwise empty end of the grip.

They may also cut down some on vibration to the hands (not shaky Harley vibration, like sonic vibration).

I use clear RTV silicone sealant to glue mine on, so I have all the time in the world to get them on and turned so the rubbers and spaces match up on each side (rubbers on top and bottom, spaces on the sides).  I wait overnight for it to set up.  Regular grip glue, super glue, etc only gives you a second and a half to get it right, and then it's stuck for good.  The overflow of RTV is much easier to clean up too. Don't glue the throttle grip to the control housing above it.

BUT, my RTV on the throttle side begins to get a little loose after a year or two, and I have to redo it.  The other side never comes loose.  

[Bighead]

 Those are not in my grips......

[Jess from VA]

The regular 5 3/4" universal Iso Grips fit the Valk fine, and do not come with spacers (they wouldn't fit).

[Bighead]

When I bought mine they were Valk specific. Bought them waaaay back around '99.

[h13man]

The regular 5 3/4" universal Iso Grips fit the Valk fine, and do not come with spacers (they wouldn't fit).

Same here and I use a standard Throttle Boss as the wide version is better suited for the Valk specific (longer) grips. I have the wide version if anybody is interested.

[Jess from VA]

The trick to using a throttle boss on the standard length (5 3/4") Iso grips (if it interferes with ordinary hand placement), is to turn it around so it sticks out past the bottom of the grip.

[BINOVC]

Thanks as usual for the info!
I got a little concerned yesterday commuting home when my wrist-twist was having trouble making the bike go through the intersection, a left-hand turn with on-coming traffic... ???
When my butt cheeks clenched, so did my grip, which re-engaged the throttle!

[vanagon40]

. . . . looks like it "used to be" threaded in.  The threads are no longer functional on the end-cap. . . .
https://www.flickr.com/photos/cocojen/42695192255/in/dateposted-public/

The extension may have never been threaded. The threads on the end of the throttle tube are for the OEM grip cap.