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« on: September 28, 2023, 12:04:56 PM »
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.