Compression Release

[Jordan]

It does seem odd but it makes no difference how the cable ends are anchored.
1960s Bultaco Metralla had the same principle for the rear brake cable, only the brake pedal end was "inside out".

https://i2.wp.com/www.bike-urious.com/w ... .jpg?ssl=1

[Jordan]

I think establishing the length of the cable in relation to the housing would be key in making this work.

The solderless nipple is great to use for this reason - it doesn't matter what length is the inner as you can move it as needed in situ.
Just make sure the outer length is good, and there is plenty of extra inner to play with (which can be snipped off later).

[Ventodue]

I guess what I don't understand is that according to the images, it looks like the cable is being pulled by the lever. The housing must pull the rocker up in order to push the valve down. How does the lever pull the rocker up?

As answered by Graeme: it's a PUSH action exercised by the cable outer, not the more usual pull action that is exercised by a cable inner. You have to think backwards a bit ...

I think establishing the length of the cable in relation to the housing would be key in making this work.

No, not so much. The cable OUTER needs to be of the right length so that it runs smoothly down from the handlebar lever to the decompressor lever. After that, you simply feed the cable inner down the outer and, as Jordan says, clamp it off at the position where the lever is pushed down when you work the h/bar lever.

Getting that position just right might take a coupla goes, but that's all. Just make sure, tho', that the clamp is well fixed. If it can move even the smallest amount down the cable inner, nothing will happen ...

It looks like the cable has to be the heavier clutch type rather than the throttle type. Correct?

Yep. Not as hefty as a clutch, but bigger than a throttle.

Addendum
Here's the diameters of the cables that Maurizio at Ducati Vintage Store supplies:
Front brake and clutch Ø 2,5. Starter (aka choke) and throtle Ø 1,3. Decompressor lifter Ø 1,9.

[frankfast]

"Here's the diameters of the cables that Maurizio at Ducati Vintage Store supplies:
Front brake and clutch Ø 2,5. Starter (aka choke) and throtle Ø 1,3. Decompressor lifter Ø 1,9."

Are there any special ends on the cable housing?

[Ventodue]

Are there any special ends on the cable housing?

Cable "housing", Frank? You mean the cable outer?

No, just a regular ferrule ...

Cable ferrules.jpg

.. which you should really crimp on (Although with spiral wound/reinforced cable ...

Spiral cable outer.jpg

... you can get away with not doing so. I didn't tell you that, btw)

At the decompressor lever end, I think it's a good idea to house the cable in one of these, called a step down ferrule. See my photos from earlier.

Step down ferrule.jpg

[frankfast]

Think I've finally got it. Thanks to all. Don't know what I would do without y'all.

[frankfast]

Sorry for returning to this thread. I thought I had the compression release done and indeed when I tried it for the first time it worked as designed. When the crank rotated and the exhaust valve opened, the lever on the compression release followed the rocker down causing the cable to jump out of the lever. Is the lever supposed to drop every time the exhaust valve opens? It seems that the cable should remain tight at the lever at all times. Also, I'm not sure where the pin that pushes the rocker down bears on the rocker. I may have a problem because the original Scrambler rockers with shims have been replaced by rockers with screw type adjusters. The original rockers and cam were worn excessively due to a broken oil pump. I'm missing something.

[Jordan]

Do you have the spring installed?

Part no. 0606.92.870

[frankfast]

That is what's missing. I thought that there must be a spring missing somewhere. I never removed the pin before so I didn't know that a spring was part of the assembly. Thanks.
Can you respond to my question regarding the change in rockers from shim type to screw type?

[Jordan]

I don't know the answer to whether the valve lifter was used on engines with screw adjustment of rockers.
Here's a couple of drawings, in case they help.
There's also a photo of someone's installation, which appears to have a spacer under the lifter assembly.