tackelhappy wrote: Thank-you both for replying. I think back to all the Triumphs I've owned with no throttle return cable and don't ever recall ever hearing about the throttle jamming/staying open . But I can understand why the second cable was added for perceived safety reasons-you never know--it might happen.
This investigation on the throttle cable set-up was prompted by inconsistent idle- so with the tank off and watching the return action of the cables I could see very small variables in where the whole mechanism would stop after opening and closing the throttle many times- there would be a very small amount of extra movement in the link rods #-65- they didn't seem to return to the same place/stop every time - small things but significant nonetheless.
So I'll try what you suggest Kawboy and tighten the decelerate cable to pull the gap closed and go from there.
With regard to why have throttle close cable. My first bike was a Honda SS50. One winter whilst driving to work VERY carefully on icy roads I managed to fall off 3 time while braking - also VERY carefully. At this point I decided to turn around and go home. On the fourth time of going down I happened to notice that my front wheel was not revolving - even after releasing the hand lever. Turned out water had got into the cable and frozen. When the brake was applied the ice kept the cable from returning.
Perhaps a frozen throttle pull cable could have a similar effect - I doubt the friction of ice in the cable could overwhelm the return spring though.
I could see very small variables in where the whole mechanism would stop after opening and closing the throttle many times- there would be a very small amount of extra movement in the link rods #-65- they didn't seem to return to the same place/stop every time
This symptom is typically associated with the sync adjusters on 1 - 2 or all 3 link-rods being screwed in too far, causing the ball-links to bind. This is the reason the manual states that the screws should be turned in lightly until they stop - then backed out 1.5 turns. This allows for some room-to-play when syncing. It's more important to achieve an accurate sync across the three carbs. without unwittingly bottoming the adjusters in an attempt to achieve a greater vacuum.
My experience with many carb-sets has repeatedly proven (on my bike) that 7.5" to 8"hg is the max. vacuum that can be achieved and still have free movement of the linkage rods.
1980 KZ 1300 sr# KZT30A-009997
Always High - Know Fear !