2000 Mercury 20HP Piston orientation?

[James R]

Had this motor sleeved after Mercury's info of 30 over boring rebuild failed. Should have known better with Mercasil rubbish.
Anyway, I note that the pistons are symmetrical with exception of the ring locators. Should the pistons be positioned with the rings locator slot position taken into account?
Thanks in advance for any input.

 

[racerone]

Any markings on the pistons ?----------Most have a mark with ---" up "--- or arrow pointing to exhaust.-----------Pictures of piston crown ?------------And any cutouts on the skirt that need to line up with ports ?

 

[Faztbullet]

Don't know what the problem was with 30over rebuild but now you have to run the proper rings on the piston for a steel bore,You will need to call whoever piston your using to find out there recommendation...

 

[James R]

Guys, I think the point was missed. There are no marks on the pistons except the size. The pistons can be oriented in only two ways and they appear to be symmetrical as far as porting is concerned.However the rings may be better off oriented one way or the other. Sorry for any confusion,

 

[racerone]

Pistons should be marked.---So contact the supplier !!

 

[Chinewalker]

Most pistons I've seen that have an oversize stamped on them - the numbers are legible when the piston is oriented correctly, .ie writing is not upside down on the dome.

 

[James R]

Remember chinewalker, this is a Mercury. The only way to see the numbers is through the plug hole. Lets try it another way. Should the numbers be on the intake side or on the exhaust side. The pistons are WSM.

 

[Faztbullet]

On WSM pistons the lasered part number usually faces exhaust. Make sure the rings as compatible with cast iron sleeve.

 

[James R]

Thanks Faztbullet and thanks to all who responded. The rings are compatible per WSM. Keep up the good work guys.