Throttle locking bolt vibrate tighter

[schrocketeer]

Does the locking bolt/ throttle screw vibrate tighter on anyone else's bike?
In my limited brick experience ('85 K100 RT, 4 years, 23k miles) I've noticed the pseudo-cruise-control locking screw/bolt tighten up several times. The first few times, I thought someone had messed with my bike.
Yes, I have replaced the cable, supporting bracket on the engine side, and the gear chain assembly in the throttle grip. I've been in the area several times, and always clean then provide a light grease coating.

. . .yet the mystery throttle tightening returns.

Is this a known problem?
Is there a reason to not remove the screw, and plug the hole?

[Laitch]

That's a weird one, schrocketeer. My throttle screw fell off and there was no consequence to me or the moto when that happened except its absence left a hole in my heart. Maybe its spring has lost tension and replacing the spring will keep adjustment stable. Does it look like this one as found at Euro Motoelectric?

[daveson]

I keep telling myself to stop posting guesses, but here I go again. If you mark the screws slot location, I'll guess it hasn't moved. Maybe something else is getting more resistance. Maybe the throttle assembly needs maintenance or the other end of the cable maybe wants another look.

[schrocketeer]

Laitch, that is what my throttle stop screw with springs looks lie.
Daveson, good point.

For a test, I've removed the screw completely, and am working on a plug for the hole to keep gunk out. Probably end up with gorilla/duct tape.

Working from one end to troubleshoot, I cut a couple of millimeters off of the end of the throttle grip, just because it looked like it may have been rubbing the bar end weight.

About a year ago, I swapped in a new cable, with the corresponding change in bracket near the throttle bodies. At the time, I lubed and checked the throttle bodies, to make sure they were free.

I'll check the cable adjuster about 1/3 from the throttle grip next. I've got a little slack to take out from initial cable stretch (minimal) from new cable installation. Then move down the line checking for binding or resistance.

[frankenduck]

Working from one end to troubleshoot, I cut a couple of millimeters off of the end of the throttle grip, just because it looked like it may have been rubbing the bar end weight.

You cut the throttle tube? You could've just loosened the clamping bolt and slid the throttle perch in on the handlebar a little.

[schrocketeer]

Frankenduck, I should have just slide the right hand assembly in further to isolate that it wasn't interfering with the bar end.
I only cut a bit off the grip, not the tube.

[schrocketeer]

It was bad throttle cable routing.
After installing a new ignition switch, I didn't pay enough attention to not binding the throttle cable between the rocker panel / ignition switch housing, and the instrument cluster.
  (not sure why that didn't dawn on me right away?)
Now it's happy and revs like it should. Happy Brick and rider. :-)

[Laitch]

Thanks for the update with the resolution of that problem, schrocketeer.