Cast in compression release

[BOREoffroad]

Looking for some feedback on this idea.
This modification has been in the works with CPI to have a boss cast into the cylinder.
This improved compression release design allows for easier access and eliminates the need for a special head.
The cylinder pictured is a first test so its not centered and looks a little off.
If this is a desirable modification that people would like to have, the plan is to move it towards the intake for optimal clearance and access to choke and release in same area.

[croat1]

I think it’s a great idea/option. 

Is anyone adding a decompression release to an existing CP cylinder?  I have a Sphinx that I’d like to add a release.

Joe

[BOREoffroad]

I think it’s a great idea/option. 

Is anyone adding a decompression release to an existing CP cylinder?  I have a Sphinx that I’d like to add a release.

Joe

I know a couple people that have cut into the cylinders and welded up an area for their personal use. But no one that I know of is offering it as a service.

[2ndmoto]

So this goes in through the side of the sleeve? Seems like it is well below the combustion chamber.

[BOREoffroad]

So this goes in through the side of the sleeve? Seems like it is well below the combustion chamber.

It is, the concept in how they function are the same, bleeding off "xx" amount of volume before TDC, lowering the overall cranking compression while open.

[havinnoj]

I think it’s a great idea/option. 

Is anyone adding a decompression release to an existing CP cylinder?  I have a Sphinx that I’d like to add a release.

Joe

I know a couple people that have cut into the cylinders and welded up an area for their personal use. But no one that I know of is offering it as a service.

For the Sphynx, last I looked which was 8-12 months ago - there were 2 options.  Rob Selvy was welding them in the cast CP head.  I had concerns about warpage - they were my concerns though, as Rob said he didn't have any related issues.  The second options was from Bob Albright - who offered them with his 2 piece head.  Those were spendy.  And Elaine @ CP told me they wanted to offer a cast head option with the boss option for the release, but to this day I still have not seen it. 

@BOREoffroad  - I like the option.  But for me it would be an aesthetic choice - the head-mounted compression release I run on my PUMA might be harder to 'find' but it does, to me anyways, look cleaner to my eyes.

[Hawaiiysr]

Not to sound like a beauty queen but I like the decomposition in the head for aesthetics as well. I'm no engine builder but going through the cylinder doesn't appeal to me

[croat1]

@BOREoffroad

Any update on the decompression release? 

Is sure like to get one done for a sphynx cylinder.  I wonder if CPI is working on anything?   I’ll have to make a call

Joe

[BOREoffroad]

@BOREoffroad

Any update on the decompression release? 

Is sure like to get one done for a sphynx cylinder.  I wonder if CPI is working on anything?   I’ll have to make a call

Joe

I have been out of the game for the past year due to health issues. So where it was left off is moving it toward the intake side for a cleaner look and so you can pull choke and release from same general area. But no progress has been made, doesn't seem to be very much demand for the change. On the test engine it worked very well, on most of the in head releases I have seen it leaves a weird burnt spot on the piston in the squish area that I don't like, even though it doesn't seem to hurt anything.

[croat1]

@BOREoffroad

Any update on the decompression release? 

Is sure like to get one done for a sphynx cylinder.  I wonder if CPI is working on anything?   I’ll have to make a call

Joe

I have been out of the game for the past year due to health issues. So where it was left off is moving it toward the intake side for a cleaner look and so you can pull choke and release from same general area. But no progress has been made, doesn't seem to be very much demand for the change. On the test engine it worked very well, on most of the in head releases I have seen it leaves a weird burnt spot on the piston in the squish area that I don't like, even though it doesn't seem to hurt anything.

Thanks for the response.  Hope you’re doing ok.

Joe

[havinnoj]

Joe last I talked with Elaine in October 2023, she said they could probably put a boss in the sphynx head, but I would need to machine it.  We never followed through on that - so sounds like there is the capability (just may mean we need to machine it ourselves).