E50 piston ring size/type

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E50 piston ring size/type

Postby RebelRider.Mike » Thu Aug 29, 2013 1:24 am

I'm considering replacing my piston rings, or at least measuring the gap to see if that is the cause of my low compression. I've thought of ordering new rings so I have them on hand when I take the engine apart, but I'm not sure of what kind to get.

I have a stock E50 engine with a number 3 piston and cylinder set. I gather that the diameter should be 38mm, but the rings available could be 1.5mm or 2mm thick, and there are the "GI", "FG", and "L" types. I don't know what that means.

I suppose I could just measure the current ring thickness to get that measurement, but how do I know which letter type to get?

Thanks,
Mike

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re: E50 piston ring size/type

Postby John » Thu Aug 29, 2013 6:07 am

This might help, was from a E50 Magnum I did. Gives some info. sorry for the resolution as this is a jpeg I had stored and don't have the original paper anymore. someone may have a better copy though. Check Mopedjunkyard for ring designation on the type of ends. Depends on the cylinder pin locations.
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re: E50 piston ring size/type

Postby mopedlar » Thu Aug 29, 2013 8:54 am

Should be "FG" ring ends.
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re: E50 piston ring size/type

Postby RebelRider.Mike » Tue Sep 03, 2013 3:47 am

I've ordered a Puch stock piston kit from 77.
It has the FG type ring ends, and should hopefully fit a group 3 E50.
They suggest I hone the cylinder lightly. I guess I'm going tool shopping again. :)
Mike

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re: E50 piston ring size/type

Postby RebelRider.Mike » Wed Sep 11, 2013 12:48 am

Well, I learned some things today.

My stock E50 uses two type FG 38mm x 2mm rings. A round notch is cut above each ring end to match up with a pin sticking out of the piston:
Image

The GI type has ends shaped to fit a round sort of protrusion in the piston.
Image

Still don't know the difference between GI and L. Maybe the L type has notches that are more square? Those seem to be for aftermarket kits anyway.

The piston kit I bought from 77 seems like it will fit my engine ok, but unfortunately, the rings that came with it broke while I was attempting to install them :( very frustrating! The kit piston also takes 1.5mm rings as opposed to the 2mm rings that work on the original piston.

I've had the rings off my old piston several times, and they're still intact. Its like these new rings should have been tempered before installation to make them less brittle.

Well, I'm going to order from Treatland, a new set of rings for each piston, and see what happens. I'm going to temper them myself this time before I try installing them.
Mike

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2014 Ural M70
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