ATHENA Cylinder Base Gasket for YAMAHA YZ 490 1984-1989

ATHENA offers this cylinder base gasket for YAMAHA YZ 490 1984-1989. The base gasket sits under the cylinder, on the crankcase. Crushed when tightened, it cannot be reused: replace it every time the cylinder comes off.

Why does the thickness matter?

The benefits:

• The OE thickness keeps the cylinder height intended by the manufacturer.
• Another thickness lets you correct piston-to-head clearance after machining or adjust the port timing of a 2-stroke.
• A new gasket keeps the bottom end sealed against oil and gases.

Why choose ATHENA?

Athena, founded in 1973 by Giovanni Mancassola near Vicenza and based in Alonte (Italy), designs gaskets, pistons and cylinder kits; it supplies original equipment to manufacturers such as KTM, Ducati, Fantic and Triumph.

When should you replace the base gasket on your YAMAHA YZ 490?

Every time the cylinder comes off: piston change, top-end rebuild or cylinder inspection. Oil or mixture seeping at the base of the cylinder also points to a tired gasket.

No manufacturer figure in hours for this model. Cross-Mania guideline: compression check every 20 h of hard use and every 40 h of leisure riding.

Specifications and fitting tips

• Thickness : OE
• Manufacturer part number: S410485006117

Cross-Mania tip: Choose the OE thickness if the cylinder and head have not been machined; if in doubt, measure the squish with solder wire before final assembly.

Spare parts and items to plan

• Top-end gasket kit : ATHENA P400485600490 · ATHENA S410485006047
• Piston : WISECO · WOSSNER
• Piston rings : WISECO · WOSSNER
• Coolant : LIQUI MOLY 1 L · TWIN AIR

Compatibility

Check the exact model and year of your bike in the list below before ordering.

Fits:
YAMAHA YZ 490 1989
YAMAHA YZ 490 1988
YAMAHA YZ 490 1987
YAMAHA YZ 490 1986
YAMAHA YZ 490 1985
YAMAHA YZ 490 1984