Fast rotating rings

[ramwing7]

I found that the compression was a bit low on my 1952 Simplex Model M engine.
 I put in some new rings with the end gap at .009" and rotated opposite each other and 90 degrees to the intake and exhaust ports.
I then installed motor in frame and started it up.  It started fairly easily and idled for a bit.
 
Then there was a "clink" and the motor stopped.

Turning flywheel showed there to be little to no compression.  My first thought was a broken rod, but that proved to be untrue.

It turns out both rings had rotated around to the exhaust port and managed to catch the edge.  This broke both rings and knocked out a piece of the land between the ring grooves. 
Fortunately, no damage to the cylinder wall.

Before I invest in a new piston and rings I want to figure out how to prevent this from occurring again.

Question is, did I do something wrong?  I'll confess to knowing very little about 2 cycle engines.

Thanks.

[Ricks]

Some of the old timers used to talk about this happening, but I have never seen it, and I have built 7 engines.  Some of them thought we should be pinning the rings so they don’t rotate.

See this thread for more info.   https://simplexservi-cycle.com/index.php?topic=389.msg2637#msg2637

[pd]

I pinned my rings back in 2015 . I haven't had a ring problem since .

" I pinned the piston , using 1/4" long x 3/32" wide compression pins .

I drilled the landings above the wrist pin , but toward the rear , to a depth of about 5/32" . The pins had to be driven in , so it's unlikely that much , if any, outward drift will happen . I squared the outer end of the pins and called them 'good for service' .

Then the ring ends needed relieving to fit the pins . I used a jewelers square file to reach that 'end' .

All things considered , I think the project turned out nicely .

"

[ramwing7]

Yep.  I think that's the way I'm gonna go. 

I guess on the bright side I have an old piston to practice on.   

And thanks for all the measurements.  They're going to save me a lot of trial and error.

[pd]

Yep.  I think that's the way I'm gonna go. 

I guess on the bright side I have an old piston to practice on.   

And thanks for all the measurements.  They're going to save me a lot of trial and error.

You're very welcome . Just helping the cause .
Let us know how it goes and maybe post a few pics .

[ramwing7]

Anyone have a standard size piston with 5/64" ring grooves they would like to sell?
I find myself badly in need of one.
Thanks.

[pd]

Anyone have a standard size piston with 5/64" ring grooves they would like to sell?
I find myself badly in need of one.
Thanks.

What happened ?

Pete .

[ramwing7]

See the original entry in this string.  Long story short, rings got caught in exhaust ports and broke themselves and the land between the ring grooves.

[Ricks]

Wayne has new pistons available.  He probably has some used ones also. 

[pd]

See the original entry in this string.  Long story short, rings got caught in exhaust ports and broke themselves and the land between the ring grooves.

Ah , yes , I recall . Now that you help my memory . LOL
One of the benefits of getting old .

Pete .

[ramwing7]

I have an order in with Wayne about 3 weeks now.  Haven't heard a word from him.

I know he's a one-man show, so I'm a bit reluctant to bug him.

[Ricks]

I have an order in with Wayne about 3 weeks now.  Haven't heard a word from him.

I know he's a one-man show, so I'm a bit reluctant to bug him.

Call him. He is old and does forget occasionally.