1998 Honda CBR900RR Cometic Head Gasket

Cometic MLS (Multi-Layer Steel) Head Gaskets

Provides maximum sealing performance for today’s high output engines and require no sealants. MLS gaskets are ideal for both aluminum heads to aluminum blocks and aluminum heads to cast iron blocks. They can withstand the shearing force created by the two materials. MLS gaskets have increased strength because they are comprised of multiple layers of stainless steel; which also creates the ability to rebound and resist corrosion. The outer layers are embossed and coated on both sides with Viton (a flouro-elastomer rubber based material that is heat resistant to 250 C/ 482 F. Viton is designed to meet the demands of a variety of harsh sealing environments, load conditions, and surface finishes. The center or shim layer is uncoated stainless steel, which can be varied to accommodate multiple thickness requirements.

What is MLS?

MLS stands for Multi-Layer Steel. MLS head gaskets are comprised of three or five layers of stainless spring steel. The outer layers are an embossed Viton coated stainless steel providing a superior seal with excellent rebound characteristics and are corrosive resistant. MLS head gaskets reduce bore distortion and withstand extreme cylinder pressures. The MLS design is also used in a superior line of exhaust manifold/header gaskets.

Can MLS head gaskets be used with motors setup with o-rings or receiver grooves around the cylinder bores? 

No. MLS head gaskets require smooth, flat and true head and deck surfaces to seal. Most of the time with o-ring setups the wire and groove fall where our gasket’s combustion seal is located; therefore, the wire will hold the gasket and not allow proper compression while the receiver grooves allow combustion gases to escape.

What surface finish is required to us an MLS head gasket?

A surface finish of 50 RA (roughness average) or finer, is recommended for a proper gasket seal. Anything rougher may conflict with the gasket design.

What head bolt/stud torque do you recommend when using an MLS gasket? 

When using MLS head gaskets always refer to the manufacturer of the fastener to determine accurate torque values. Appropriate torque is critical when installing new gaskets of any kind.

Why does Cometic recommend MLS gaskets to be installed dry? 

Cometic Multi-Layer Steel (MLS) head gaskets go on dry because they are coated with a sealant. Each MLS head gasket is coated with a .001" thick Viton rubber that is bonded to the outer stainless steel layers. Adding an additional sealer can hinder the performance of an MLS head gasket.

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Cometic Head Gasket fits the following vehicle(s):

• Part Number fits: C8406 (12930)
• 1993 Honda CBR900RR
• 1994 Honda CBR900RR
• 1995 Honda CBR900RR
• 1996 Honda CBR900RR
• 1997 Honda CBR900RR
• 1998 Honda CBR900RR
• 1999 Honda CBR900RR