Cylinder Sleeve Design

[Kosiba]

I Just started watching this youtube series of a guy making a motorcycle engine from castings, and when he started machining the cylinder sleeves he had cut a small relief into the sleeve, and then I went to look on one of my 2 stroke nitro sleeves and saw that there was one there too, and now I'm left wondering what they're for and how would you go about actually designing different cylinder sleeves? Like how could/should you position the holes on a 2 stroke sleeve, or what does that relief actually do?

The relief would be right below the lip at the top, this one doesn't have it

And this on does have it


All help understanding this would be greatly appreciated!

 

[GreenTwin]

Jeff Henise casts his own racing motorcycle cylinders.
I can only guess that the relieve allows for a complete sliding fit of the sleeve into the cylinder, with no possibility of it seating slightly high.
I think Jeff heats the cylinder, adn then presses in the sleeve.

https://www.homemodelenginemachinis...se-casting-motorcycle-racing-cylinders.35502/
.

 

[Kosiba]

Jeff Henise casts his own racing motorcycle cylinders.
I can only guess that the relieve allows for a complete sliding fit of the sleeve into the cylinder, with no possibility of it seating slightly high.
I think Jeff heats the cylinder, adn then presses in the sleeve.

https://www.homemodelenginemachinis...se-casting-motorcycle-racing-cylinders.35502/
.

Thanks, any idea on how to design a 2 stroke cylinder sleeve?

 

[GreenTwin]

I seem to recall seeing a book that discussed ports and such for a 2-stroke.
I am not up on that design technology though.

.

 

[Kosiba]

I seem to recall seeing a book that discussed ports and such for a 2-stroke.
I am not up on that design technology though.

.

Can you remember the name of the book?

 

[GreenTwin]

The name of the book was "Tuning for Speed", by P.E. Irving, Temple Press Books, London, 1960.
First Ed. 1948.

The two stroke information is a bit dated, and mentions a rotary valve.
The modern two-stroke motorcycle engines use valves in a cage just downstream of the carburetor.
There is some port information, so it may be useful.
Better than nothing for sure.

The 4-stroke information in this book is very good.

.

 

[Kosiba]

The name of the book was "Tuning for Speed", by P.E. Irving, Temple Press Books, London, 1960.
First Ed. 1948.

The two stroke information is a bit dated, and mentions a rotary valve.
The modern two-stroke motorcycle engines use valves in a cage just downstream of the carburetor.
There is some port information, so it may be useful.
Better than nothing for sure.

The 4-stroke information in this book is very good.

.

Thank you very much! I'll try to get my hands on it asap!

 

[GreenTwin]

Here is one currently on ebay.
Some on Amazon too, paperback I think, and probably a reprint.

 

[Jasonb]

I've not looked at the video but if he is using insert tooling that all has a radius to the tip of the tool to some extent. If you were to drop that liner into a cylinder that had a square external corner then it would not seat down correctly. The groove give sclearance though the external corner of teh block should also be at least deburred or slightly chamfered.

As drawn your one has completely square internal corners which can become stree risers, if teh parting tool used to cut teh relief has rounded corners then you will get a stronger liner, the common GTN type parting inserts have these rounded corners.

Myself I use an insert with small 0.2mm tip radius and ease the cylinder block so no need for an undercut on engines that I build.

You will also see the relief groove being used for threaded components with a shoulder as you can't easily thread right upto the shoulder.

 

[lohring.miller]

There's a lot to two stroke design. I've written several series of articles on high performance ones. It would help to know exactly what type of engine you want to build. Below is a history of model, high performance two strokes.

Lohring Miller

 

[Kosiba]

Here is one currently on ebay.
Some on Amazon too, paperback I think, and probably a reprint.



View attachment 165327

Thanks I'll check if I can go to a library and check it there too.

 

[Kosiba]

There's a lot to two stroke design. I've written several series of articles on high performance ones. It would help to know exactly what type of engine you want to build. Below is a history of model, high performance two strokes.

Lohring Miller

Read it through and I don't quite understand most of the terms used when referring to the bypasses, but it definitely made me quite a bit more interested, and I now have questions about why most modern or relatively modern 2 stroke engines don't use any sort of piston ring?

 

[Kosiba]

I've not looked at the video but if he is using insert tooling that all has a radius to the tip of the tool to some extent. If you were to drop that liner into a cylinder that had a square external corner then it would not seat down correctly. The groove give sclearance though the external corner of teh block should also be at least deburred or slightly chamfered.

As drawn your one has completely square internal corners which can become stree risers, if teh parting tool used to cut teh relief has rounded corners then you will get a stronger liner, the common GTN type parting inserts have these rounded corners.

Myself I use an insert with small 0.2mm tip radius and ease the cylinder block so no need for an undercut on engines that I build.

You will also see the relief groove being used for threaded components with a shoulder as you can't easily thread right upto the shoulder.

So these reliefs are mainly just for clearance for sliding the sleeves into the block?