Odd right switch/throttle interference

[paul in rochester]

So, I was doing some much delayed odds'n'ends stuff in getting my Jackal up to snuff for the season-late, but that's just how it goes this year.
Anyway, there was a bit of a hitch recently in the throttle, so I pulled the cable to clean, lube, and check the routing. I put it all together, and found that there was a "step" that holds the throttle open.
The throttle barrel on the bars, that holds the end of the cable, is getting hung up on the switch housing:



This is where it stops. The weird thing is that, at this point, the throttles are still a fair amount open. To get the throttles closed, like usual, you need to close the throttle past that point:



Now, nothing's changed at all-the cables, the throttle pipe, and the switches are all original. I didn't bother with the recall way back when to add a second (closing) cable-it was too much of a bother.
I'm sure that I can cut/grind/modify my way around this, but it's really weird, what with this suddenly happening after almost 20 years.
Has anyone else had oddness like this happen?

[Old Jock]

Can't comment on the Jackal specifically as I don't know it

I've found in the past though that if the 2 halves of the housing are done up too tightly the barrel with get squeezed and the throttle needs to be pushed or pulled to fully close it.

Usually in my experience the bolts connecting the 2 halves of the housing onto the bar don't have to be screwed in very tight, looser usually than I expect

It could of course be something entirely different so forgive me if that's just too obvious

John

[Wayne Orwig]

Is there a chance it is at the airbox?
One reason for the recall, was that the air box could rub the throttle cam down there under the tank. Then the throttle would stick open. The second cable as for safety of course.
Some people have gotten the airbox really warm and changed the shape so it does not rub.

Or is the problem at the throttle itself for sure?

[John A]

^^^^ this is the most likely cause and there was a recall to add a return cable to pull it closed.  There have been riders hurt by it when the throttle unexpectedly won’t close.  It surprised me but I didn’t wad it up that time...

[pehayes]

The airbox interference wasn't an issue of the airbox itself.  The intake tract has a rubber attachment collar or bushing for each side (Guzzi calls it a manicotto or hose).  The collar is located between the throttle body and the intake manifold on the head.  On the interior of this collar there are elaborate ridges cast to help register and retain the correct, full installation.  Each of these rubber collars requires TWO hose clamps to keep it in place.  IF the clamps were not tight and IF there were a small backfire explosion into the intact tract, the resultant pressure burst could push the throttle body slightly aft.  Just enough so that the central portion of the cross linkage would interfere with the front face of the airbox.  Throttle jams open.  You crash.  Second cable recall didn't solve the underlying problem of a loose collar but it did allow you to override the interference and PULL the throttle bodies closed.

Go back and loosen all the clamps.  Make sure everything is seated home quite completely.  Re-tighten the clamps and do it well.

Patrick Hayes
Fremont CA

[John A]

I’ve noticed that the first clamp, closest to the head, can start to roll off the rubber if I tend to over tighten it.  I make sure the rubber and clamp are clean and dry especially if I’ve used some type of lubricant to get the rubbers to act right when I put them on.

[paul in rochester]

So, this 'notchiness' is there with the cable disconnected from the throttle bodies, AND with the cable out of the loop. I cleaned things up, reattached the switch housing screw less tight, and we'll see what's what.

Thanks for the ideas!

Paul