Compression Release

[frankfast]

I want to install a compression release on my 350 Scrambler. I've seen pictures of the mechanism at the valve cover and I've read that the housing on the cable is what actually moves the rocker that bears on the valve. That must mean that the cable is fixed at both ends and the compression release lever moves only the housing. Is that correct? A picture would be worth a thousand words. Thanks.

[Jordan]

That's correct.

There are two ways that Ducati installed the valve lifter.
One has the inner cable terminated at a hole drilled in the rocker cover, the other way uses a small plate clamped under the left front cyl/head bolt.
Its part number is 0606.92.840, it can easily be made from 3mm steel plate.
I think the plate method looks neater.
The mechanism can rotate 360 degrees, and fastened in a position according to which method is chosen.

https://www.ebay.com/itm/183735722916?chn=ps

https://www.eurojamb.com/products/ducat ... 606-92-840

https://static.wixstatic.com/media/e758 ... 0/file.jpg

[frankfast]

Thank you Jordan. I became familiar with the workings of the release at the valve cover but haven't seen what the lever looks like and how it moves the housing. I recently purchased a lever and need to provide a cable for it. It seems to me the lever is installed 'bacwards' on the handlebar and would go on the left side. Also any advice providing a cable would be helpful. Thanks.

[Jordan]

There's nothing special about the handlebar lever, a normal type that pulls the inner while the outer is anchored works.
I find a "choke" lever works well on my single, with the friction device adjusted so it moves freely.
For SCR models a combined clutch/valve lifter lever was supplied.
https://www.ebay.com/itm/372967827758

The cable should be easy to arrange, as in typical Ducati single fashion is uses a solderless nipple.
Getting lengths exactly right is not so critical, as the nipple can be moved just where it's wanted.
It helps on mine to adjust the relative length, unlike the SCR that has provision for screw adjustment.

[Ventodue]

Hi Frank,

Did this earlier this year on my Vento (with considerable help from Jon Pegler who supplied the valve cover and matching lever).
Definitely worth doing - I can now start the beast off its stand

1. Yes, handlebar lever on the left side. Be aware you need a hefty item. I started off with a little toy-town item which simply couldn't exercise enuf pull to depress the valve. Second attempt worked, using a more 'manly' Domino item. See photo below.

2. As Jordan said, the abutment for the other end of the cable is simply a nicely shaped piece of thick steel with two holes in it.

Photos attached. Yell if anything not clear or you need more info.

[Ventodue]

For SCR models a combined clutch/valve lifter lever was supplied.
https://www.ebay.com/itm/372967827758

Good point, Jordan.

Yes, that's the neatest solution, Frank (and is what I have on my 450 SCR).

(Couldn't use one on my Vento (as mentioned above) 'cos I wanted to retain the original clutch lever and switch block).

[frankfast]

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?

[frankfast]

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

[graeme]

The inner cable fixed at the head can’t move up so the outer sheath pushes the lever down.
Thus pushing on the rocker and opening the valve.

[frankfast]

Thanks Graeme. I was mistaken in that the housing pushes the rocker down. I think establishing the length of the cable in relation to the housing would be key in making this work.Since the lever acts on the cable and is fixed at the other end, how is there movement on the cable? I guess that is what I don't understand. In most applications the housing stays fixed and the cable moves within the housing.