It's always a good idea to keep a spare gasket on hand when opening your sidecase. Any rips or tears to the gasket while removing the sidecase will require a gasket replacement.

Flywheel Parts: TRX450R 2004-05 Side Case Gasket
$9.95
6600-G01
2004/2005 Honda TRX450 Side Case Gasket..

Flywheel Parts: YFZ450 04-09 Side Case Gasket
$9.95
6500-G01
YAMAHA YFZ450 04-09 Side Case Gasket

Flywheel Parts: Z400 Side Case Gasket
$9.95
6800-G01
Z400 Side Case Gasket