Correct way to install piston

[1998RM250]

Gettin ready to button up the CR 250 and I want to make sure I put the piston in correctly since I can't find the arrow (cast prox). What could I use to clean off some of the carbon on the piston dome? To my knowledge if there is no arrow, the side of the piston that holds the ring in place goes on the intake side. Any input? Thanks

 

[RM_guy]

You are right on the piston placement. You don't want the ends of the rings catching on the exhaust port.

Some Scotch Brite works good to remove the carbon. Avoid scraping it with something sharp. Gouges on the top of the piston are not a good thing.

 

[IndyMX]

Arrow or no, the opening in the rings always should be opposite the exhaust port.

 

[pesky nz]

Arrow or no, the opening in the rings always should be opposite the exhaust port.

On everything modern that I have seen I agree but I have seen old Kawasaki road bikes with the ring gaps either side of the exhaust port. So always check by putting the piston in the cylinder without rings if you are unsure, but first mark the ring pin location on the piston top with felt pen, and the ring pins will line up with cylinder wall from the top of the cylinder down to the bottom of the transfer port height