2pg engine new cylinder compression low

rthompson

I rebuilt the top end of my 1979 ez-go Marathon and the compression is low 60 psi. I ran one tank of fuel through it and I took it apart. You can see a leak around my rings right where the little stud is in the top ring groove. I took the rings out and looked at them with a magnifying glass and I think they are in with the bevel up. I have another engine I took apart same year and model I swaped the heads. In case one was warped. Does anyone know what else I should do. It is driving me crazy. It runs OK but compression is very low and it is sluggish. I don't want to put the engine back in if there is another cheap option.

BGW

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Heliarc

Reed valves perhaps?Just a guess but I believe they hold back compression as well.You can take off your carb, then intake and the reeds will be right under the intake.Check for cracks or chips or anything.They should also lay good and flat against the reed block.I took mine out and they mostly held a vacuum.

rthompson

I ordered new piston rings. I hope that does the trick. It seems like one of the rings are sprung. Thanks for the idea about the reed valve I will check that as well.

racin161

Be sure to ball hone the cylinder and apply a bit of 2cycle oil in the piston bore and the piston when installing. Clean the cylinder well with carb cleaner before assembly.I load the piston in the cylinder ports facing the carb side then lower it over the connecting rod and slide the pin in. Don't forget the base gasket LOL Before installing the head get some 220 wet or dry sand paper place it on a flat surface I use tempered glass and move it in a 45 deg angle both ways until you see contact completely across the head surface NO high or low spots Don't forget the new head gasket LOL. Have you replaced the crank seals ??? Well that's my input Good luck and report back.

LOU

rthompson

Thanks, I will do all that. I need to order all new gaskets as well. I replaced the seals 6 months ago.

racin161

Should be good then. Good luck this time!!

LOU

rthompson

Replaced the rings and gaskets ran excellent for one day. The compression was alot better and it was awsome right up until it quit. I need to see what is up. The gas was coming out of this little beather tube and it turns over but won't start. It got pretty hot but didn't make any clanking sounds. It went about 2 miles then I had to get towed back with my electric cart.

racin161

needle is stuck or dirt on the float seat. Clean the carb and replace the plug and it should go again.

Heliarc

Nailed it

rthompson

Thanks!