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Can piston rings rotate?

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I just finished a valve and ring job. However when I checked the rings, the gaps were pretty much out of position. I noticed last year that you could smell the exhaust a bit more. Since I put in new piston rings, the exhaust smoke is gone with no smell. Just wondering if they were installed out of spec or the rings rotated to a bad position.

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I doubt rings could rotate without being severly worn. I would think they came from the factory like that. Were those the stock rings that were out of alignment?

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Yes, piston rings can rotate. In applications where rotation would be bad (as in 2 strokes) the rings are pinned to prevent rotation. Some 4 strokes also pin the rings but it is not very common.

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4 stroke rings are made to spin in the piston. You need them to rotare on the piston, but to fast. The rotation is dictated by the cross hatch in the cylinder. Too steep of cross hatch and your rings will rotate to fast or too flat of cross hatch will not rotate fast enough.

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4 stroke rings are made to spin in the piston. You need them to rotare on the piston, but to fast. The rotation is dictated by the cross hatch in the cylinder. Too steep of cross hatch and your rings will rotate to fast or too flat of cross hatch will not rotate fast enough.
I don't think so.

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4 stroke rings are made to spin in the piston. You need them to rotare on the piston, but to fast. The rotation is dictated by the cross hatch in the cylinder. Too steep of cross hatch and your rings will rotate to fast or too flat of cross hatch will not rotate fast enough.

Umm, No

:)

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4 stroke rings rotate around the piston. It serves to keep the ring grooves clean and free of sludge. Two stroke rings are pinned to keep them from snagging a port.

Valves rotate too, not fast perhaps, but they do. Before reading this, I can't say I ever thought about what RPM the piston rings and valves are are rotating before though.

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The rings do move in the grooves. The fact that 2smokes have to pin theirs to keep them from rotating and snagging a port should be a strong clue to the uninformed... but it is a commonly known fact in engine building that the rings can/will move in the grooves. How much is purely dictated by the millions of variables native to each specific cylinder. You set the gaps at thirds during install to try and keep the gaps from lining up, in hopes that when one ring moves they all are moving at the same rate. If you found your gaps lined up, it was probably from wear that allowed the ring to relax and there was less radial tension to keep the ring from rotating as easily... :) Andrew

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I have cum across it a few times in text books

According to Four-Stroke Performance Tuning

Page 246

Rings rotate at approximately 1/1000 of the rpm

Never seen a reference to honing pitch though

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some of you might say they should not rotate. I work for a piston mgf and have training seminars on piston rings. so think what you will.

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