I believe the rings will already come preinstalled on the piston, but how do you position them. Do you do it just like the manual if it was still a 250.

Manual says top ring and 2 bottom rings face forward and the second ring and oil expander face rearwards. Then the bottom rings need to be turned 30-40 degrees of an angle from the opening of the top ring. Do you turn both bottom rings in the same direction, or do you turn 1 left and 1 right.

Page 4-26 in manual

So, what prevents the rings from turning inside of the cyl. while it's running?

 

Whats most important is that the gaps are not lined up. I just made sure they were all 30-40 degrees apart. The rings dont spin while its running. How can they? They are pushing against the cylinder wall, and the piston travels up and down. They dont spin.

 

I think you may find a myriad of opinion and information to the contrary.

 

dont believe everything you read in the internets.

 

I think you'll find that they do indeed "spin" inside the cylinder.....

 

Perhaps. My stock ones came out offset by the 30-40 degrees. And the new ones should go in the same way as EMS recommends. Follow the manual.

 

i agree that the rings should be installed offset as in the service manual, however if the rings did not move there would be no need for ring dowels like 2 stroke engines have.

 

The rings spin... the theory with offsetting them is that with the idea of random diversity; they will have a very low probability of ever lining up all at once. Valves spin too. And so do bearings... :-P

 

I'm too lazy to go back and research this, but if I recall a 2-stroke "must not" allow the ring gaps to move as the end gaps could hang on a port in the cylinder. 4-stroke rings do move around in the cylinder...generally.

 

Two stroke pistons have a pin in the ring groove to stop the rings from spinning. The rings have a cut out on the inside to allow the pin.