Review on Athena P400485100024 Cylinder Yamaha Engine by Jim Acquista

Poor casting quality of the cylinder. Lots of air bubbles in aluminum, which means lots of pitting in Nikasil. The port timing was for a 421 (+4mm) stroke crank so the timing is absolutely not stock and the transfer ports are hidden by the piston and are smaller than stock due to the odd timing. very poorly adjusted 392. I bet it would be great like 421.