The
only piston style available from Onan for the B & P series engines
is shown in the photo on the upper left side, casting # 112-0277 and
use's Ring Set Part # 113-0310.
If
you only have one bad piston and it looks exactly like the one pictured
on the upper left with casting # 112-0277 no problem. If your pistons
look like the three other styles you will need to replace both to avoid
an out of balance engine.
Onan
manufactured four styles of pistons for the B & P series engines
over the years. The two pictured on the bottom look identical but have
different casting numbers and use different ring sets. Always check the
thickness of the compression rings before ordering!
Part # 113-0310 Ring Sets have .057" thick compression rings.
Part # 113-0314 Ring Sets have .077" thick compression rings
