Has anybody else drilled holes in their Pro-X pistons so they are like the Wieseco's? I drilled 3 small holes vertically in mine.
ERIC

 

i have not needed a drill in the past, because the holes in my pistons usually occur naturally. and they always seem to end up on the top. go figure.

 

Retro are you talking about the hole you drill to help lube the exhaust bridge?

 

Yes sir, that's what I mean.
ERIC

 

yes,these will help cool the exhaust bridge. To do this without making a mistake you should take a black marker and shade in the exhaust side of the piston where you will be drilling.Then assemble the piston,pin and bearing(no rings or c-clips needed for this step),put the cylinder on and snug down the base bolts. Next turn the crank so the piston is just starting to open the exhaust port, take a scratch awl and mark the bridge loction on the piston. Very little pressure is needed to make your marks. Disassemble and drill in the area between your marks. locate them about the same distance down as your old wiseco piston,or make 2 or 3 holes about 3/16 apart about 3/16 down from the second piston ring. hope this helps.

 

The Wiseco sheet says to relieve the exhaust bridge .006 and drill the holes. I have heard to relieve the bridge .020 and not drill the holes. Do you have experience with both ways and know of any advantages of one over the other?

 

What does it mean by RELIEVE?
ERIC

 

What he means is to cut material off the front of the exhaust bridge that comes in contact with the piston. I would rather keep the exhaust bridge at 6 thous. and drill the piston. The more support for the piston the better.