I had to replace the cylinder on my sons bike. The old cylinder had no dowel pins(stops) for the exhaust valve adjustment. The new cylinder has one lower pin installed. The service manual says to install a 5.5mm pin in the upper hole for proper exhaust valve adjustment. (I bought the bike used 3yrs ago.) So I guess my question is "who is correct"? Is it possible to remove the dowel(stops) for a performance application or did the previous owner disregard the adjustment? Should I follow the manual or could I leave the dowel(stops) out for performance? Any info would be helpful.