Topic: Return/Push Throttle Cable Issue

[theofam]

I'm working on Paddy, my '78 750K, and I'm experiencing trouble with the top cable at the carb's bell housing.  I believe this is the "return" or "push" cable.

I had the pull cable installed and adjusted to where it snapped back perfectly, then I adjusted slack out of the throttle on the other end of the pull cable by the throttle/right control.  Everything was awesome!

Now, to install the return/push cable.  I couldn't get it installed, so I added slack back in at the throttle/right control.  Then, I got the return/push cable installed.

Here's my issue, no more snap back of the throttle.  In fact, it sluggishly closes and requires me to fully close the throttle the last 1/2".  Unlike the pull cable, it only has one nut on it (see below pic).  Does it need a second nut to allow adjustment of the cable?

I've tried searching other threads, but to no avail.  So, thanks in advance for any insight you can provide!

[OneWheelDrive]

Where are the caps that go on the tops of your carb slides?!  I'd be concerned about debris dropping into the slide and needle chamber.

The return cable should be loose enough that it doesn't have tension, but is there as a backup in case the carbs don't close with the tension of the carb spring.

The pull cable definitely has two nuts and the return only has one.

[bollingball]

OneWheel has a point put the caps on before crap falls in. The bottom cable opens the slides the top is what some people call the push but it does not push just look at it it  pulls also. Both should have a lock nut on them but not the choke. You may have got them backwards to check take them off pull all slack out at the carb end while holding on to them slowly rotate handle to open and see which one start to pull in that will be your bottom cable get a nut on there first. Hope this helps I have the same bike and they should be PD 42b carbs report back or PM

[theofam]

I've the carb caps off so I can sync the carbs.  I've been covering them when not working on the throttle cables, but your points are well taken - I'll get the covers on them before the inevitable happens.

Does anyone have a pic of their top/push/return cable installed?  I've got it set as loosely as possible, and it's still not letting the bottom/pull cable close the throttle or snap the slides closed.

[TwoTired]

Cables have the least movement resistance when they are straight.  Each bend creates friction and tighter bends create more friction.  Often the fiction is not apparent until the cable has tension on the inner core.

You should address the cable routing as the straightest path is the most trouble free.  If bars have been changed, this also means that the cable must change length, in order to correct the severe bend placed on them.

There is no adjustment on the pull closed cable.  There are two on the pull open cable.  One near the carbs and one by the twist grip.  You only adjust twist grip free play with these adjustments, and you should be able to move the grip a little with no carb slide movement.  Too tight and the throttle won't return easily.

Are these old cables or new?  Old cables that are fraying internally increase drag when in tension.

Cheers,

[theofam]

TT, thanks for the great description of the cables.  I'm glad to know there is no adjustment on the pull closed cable - that's what I had concluded, so it's nice to verify.

I'm running stock handlebars and, likely, original cables.  If they're not, they're at least "old."  Given the pull open cable works flawlessly prior to installing the pull closed cable, it appears I need to replace the latter.

Again, thanks for weighing in on the matter.

[midnightrider]

Yep, routing is a big factor. 

It will also help to lube the cables...you can get a cable oiler from harbor freight for cheap -
http://www.harborfreight.com/cable-oiler-66640.html
They'll probably try to charge you $15 for it at a motorcycle shop.

You may also want to spray the whole mechanism with some oil...it will lube it all up and protect against rust.

[theofam]

Thanks midnightrider.  I lubed the cable today and still no go.  It's worn through the protective sheath to the metal casing in a spot, so I think it might be crimped in there.  It's sliding, just not well enough to let the pull open cable snap back closed.  Time for a new one!