Aprilia throttle linkage

[welleyes]

I am trying to get the working of the throttle linkage clear in my mind.  The hand throttle cable is responsible for ensuring that the carb returns to the closed position because it holds the tapered lever (38-63514 {38-0848A/IR}) in position; the cable hooks on to the end of the tapered lever.  As well as opening the throttle via the hand throttle, the tapered lever resists movement of the sleeve (38-63528) which holds the pedal return spring (38-63532) in tension so that the throttle will close when the driver’s foot is off the accelerator. In other words, a broken or disconnected hand throttle cable would leave the carb unable to snap back to the closed position. There is also a return spring (38 63517) for the tapered lever; in order to have any effect, that spring would have to be tensioned by rotating the pillar on which the lever sits and then tightening the nut on top to hold it in the tensioned position. Is that right? I cannot see any obvious way to turn the pillar and to hold it in position while tightening the nut. The spring for the tapered lever seems redundant anyway as everything works anyway when the spring is slack. What does the spring do and how? What am I failing to understand?

Stuart

[simonandjuliet]

Let me read that again ....

if the hand throttle cable is broken, the carb does close because of the spring, the friction on the lever under the dash just holds it in position

The spring around the shaft does hold the throttle closed and everything else works against it

[welleyes]

Sorry, Simon. You are quite right; I posted before I had properly finished explaining. The final link in the setup is the ball jointed piece which attaches to the carburetter. On ours, the top ball joint was not very good (now replaced with a new one) and it jumped off the ball if the lever was not there to act as stop. We must have been driving around for many miles with the lever and cable doing that duty. When the linkage was offered up as a trial without putting the lever etcetera on, the original ball joint popped straight off. When I put the lever back on, all was well.  However, I could not see what the smaller spring operating on the lever was actually doing as it made no close contact with the lever. It would if the piece that the lever pivots on was ‘wound up’. Is it meant to be?

If this is confusing, I can only say that if you could see me pointing to the bits, it would be crystal clear. I repeat that the duff ball joint has been replaced anyway. Incidentally, the final horizontal piece of the linkage does not look like the illustration in either the S1 or S2 parts book.

Stuart