First some history.....motor started running very rough, and burning a ton of oil (like a chimney out the valve cover vent). Compression was 30 on one cylinder and 90 on the other. On the 30 compression cylinder when I turned the crank by hand, I could hear a sort of crunching sound which I was certain was a ring (or piece of one) floating around inside the cylinder. Additionally, after removing the head, I discovered there was a slight amount of play in the cylinder (ie. with my fingers I could move the piston very slightly back and forth within the cylinder).

After removing the motor, dropping the oil pan and removing the pistrons, to my utter amazment, the rings are all seated properly, and appear to be fine (at least to my untrained eye). I compared the two pistons for any differences in the rings and there isn't any...as far as the rings go everything looks same between the 90 and 30 compression cylinders.

Knowing something was causing the crunching sound, I searched the oil pan and the rest of the block for some sort of foreign object, but came up with nothing.

The cylinders themselves look fine....no gauges or groves that I can see. Used my fingers to go up and down the cylinder walls and couldn't feel anything either...it all seems smooth.

Finally, I can see a buildup on carbon from all the burning oil on the side of the piston from the low compression cylinder right near the top. It is a small band of carbon about an inch in length and extends from the top edge down about an eighth of an inch. It is directly above the pin that attaches the piston to the arm (sorry, don't know the proper name of that piece).

So....now what? I have no clue what caused the loss of compression, the play in the piston within cylinder or the crunching noise. Could a ring get out of it's groove, cause all of the above symptoms and somehow get back in its groove when I removed the piston? Sounds crazy, but I don't know what else to think.

Any other ideas/theories??

I guess I could reinstall the pistons and see if there is still any play in the one. If there isn't, then obviously something changed with the rings.

I'm no mechanic, so if anyone has any thoughts, I'd love to hear them.

Thanks in advance.

Confused in Calgary!

P.S. Tried to take some pictures, but the camera battery died. Will try and post some shortly.

Take the parts to an auto machine shop to mic the cylinders and look at the pistons. They will probably do this for free if you have them do the machine work. Take the head with you and explain what it was doing.

Mike

Take a comp ring off the piston and check the ring end gap inthe cylinder top middle and bottom see if in specs .Sounds to me the rings just wore out or the bore is wore out .Dont know about the crunching sound tho

Check everything they said, but don't rule out a bad valve in the
head, bent valve,broken valve spring,valve guide-seal. Let us know
what you find.

There is a guy on here selling a 800 CC engine and trans with the wiring harness if you are interested he is asking $1000 + shipping I have his info in a PM if you are interested.

Mike

There is an exact replacement engine/transmision on EBAY. The price is BUY IT NOW for $859.00 plus $225.00 shipping. Search EBAY for Water Cooled 650cc.
If that is an option.
Clint

Thanks Clint!

I've also been searching ebay, but didn't come across that ad.

Much appreciated!