weisco piston oiling holes

[yeppimcody]

okay so i lost my instalation directions for my 250r weisco piston. but i found one on line it says i need to drills holes in the pison by the exhust port? is this right? what do thes do if its a 2 stroke???? does it hurt if i wouldnt drill thes holes? :wondering thanks guys!

[riverrat]

I just installed an ESR big bore kit with a wiseco piston, and the exhaust side had 3 little dimples on the side of the piston. Those dimples are to bring up oil to the exhaust bridge, and help keep it cool. I can't tell you how to do it though. From memory (which sucks) they were like 1/16th spread out about an inch vertically, right where the arrow is (exhuast side).

Funny thing for me is, the new ESR cylinders have no bridge now.

[Dirtcrasher]

They do that to cool the very thin exhaust port, thinner metal heats up faster.

I thought it was 3/8 and 5/8ths below the bottom oil ring and I forget the diameter of the hole.

[Bryan Raffa]

best I can do...