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Start ShoppingCometic C9185 Twin Cam EST Gasket Kit - Premium MLS Engine Sealing Kit for Harley-Davidson Big Bore Builds
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Description
Upgrade your Harley-Davidson Twin Cam engine with Cometic's C9185 EST Gasket Kit, engineered for maximum sealing reliability and performance. This premium kit combines multi-layer steel (MLS) technology with advanced materials to ensure long-lasting durability in high-output big bore builds.
Key Features
- MLS Head Gaskets (Pair, EST Design): High-pressure sealing for enhanced engine efficiency and reduced compression leaks.
- Steel-Core Seals with Viton/Rubber Coatings: Resists heat and oil degradation for superior sealing in critical engine components.
- Fiber/Aramid Materials for Cam Cover & Rocker Seals: Reinforced durability for high-stress engine environments.
- Assorted O-Rings & Small Seals: Complete coverage for all top-end and lower-end service requirements.
- USA-Made Premium Materials: Manufactured in the U.S. with aerospace-grade components for unmatched reliability.
Why Choose This Product
Cometic's EST technology delivers precision-engineered sealing solutions specifically designed for Harley-Davidson Twin Cam performance builds. This comprehensive kit eliminates the need for multiple purchases by including all essential gaskets and seals for a complete engine rebuild. The combination of MLS head gaskets, reinforced steel cores, and advanced coatings ensures optimal sealing under extreme conditions, while the USA manufacturing guarantees quality control and compatibility with factory specifications. Whether you're upgrading your big bore engine or performing a rebuild, this kit provides the reliability needed for long-term performance and peace of mind.
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Upgrade your Harley-Davidson Twin Cam engine with Cometic's C9185 EST Gasket Kit, engineered for maximum sealing reliability and performance. This premium kit combines multi-layer steel (MLS) technology with advanced materials to ensure long-lasting durability in high-output big bore builds.
Key Features
- MLS Head Gaskets (Pair, EST Design): High-pressure sealing for enhanced engine efficiency and reduced compression leaks.
- Steel-Core Seals with Viton/Rubber Coatings: Resists heat and oil degradation for superior sealing in critical engine components.
- Fiber/Aramid Materials for Cam Cover & Rocker Seals: Reinforced durability for high-stress engine environments.
- Assorted O-Rings & Small Seals: Complete coverage for all top-end and lower-end service requirements.
- USA-Made Premium Materials: Manufactured in the U.S. with aerospace-grade components for unmatched reliability.
Why Choose This Product
Cometic's EST technology delivers precision-engineered sealing solutions specifically designed for Harley-Davidson Twin Cam performance builds. This comprehensive kit eliminates the need for multiple purchases by including all essential gaskets and seals for a complete engine rebuild. The combination of MLS head gaskets, reinforced steel cores, and advanced coatings ensures optimal sealing under extreme conditions, while the USA manufacturing guarantees quality control and compatibility with factory specifications. Whether you're upgrading your big bore engine or performing a rebuild, this kit provides the reliability needed for long-term performance and peace of mind.| SKU | GMAAD1B359 |
|---|---|
| MPN | C9185 |
| Brand | Cometic |
| Category | Gaskets/Seals |
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Featured Review
| Make | Model | Years |
|---|---|---|
| Harley-Davidson | FLH/FLT Twin Cam 88 (bagger family, carb and early EFI) | 1999-2006 |
| Harley-Davidson | FXD Dyna (Twin Cam 88) | 1999-2005 |
| Harley-Davidson | Softail Twin Cam 88B | 2000-2006 |
Frequently Asked Questions
Yes. C9185 is an EST engine gasket kit that includes Cometic multi‑layer steel (MLS) EST head gaskets along with base gaskets, rocker gaskets, cam/primary gaskets, and related seals.
It is designed for specific Twin Cam applications and bore sizes. Always verify year, model, and bore with Cometic’s catalog or tech support before ordering, especially on big‑bore or high‑compression builds.
Most EST/MLS head gaskets and many cover gaskets are intended to be installed dry. Use sealant only where the Harley‑Davidson or Cometic instructions call for it, such as certain case seams or plug points.
Yes. EST MLS head gaskets are commonly used in performance and big‑bore Twin Cam builds due to their improved sealing and durability. Confirm thickness and bore size requirements with Cometic.
Experienced home mechanics with the proper tools and a service manual can perform the work, but for head gasket and cam chest work on Twin Cams, many riders prefer to have a professional engine builder handle the job.
Installation Guide
Difficulty
Hard
Est. Time
6 hr 0 min
Tools Required
- Factory service manual
- Complete SAE socket and wrench set
- Torque wrench (inch‑lb and ft‑lb)
- Allen / Torx bits used on Harley Twin Cam
- Flywheel locking tool or suitable crank locking method (if removing primary)
- Cam bearing / cam removal tools (for cam chest work)
- Razor scraper or plastic scraper
- Solvent / brake cleaner for gasket surfaces
- Straightedge and feeler gauges (to check head and cylinder flatness)
- Thread chasers / taps
- Torque angle gauge (recommended for head bolts)
Pro Tips
- Carefully read Cometic’s instruction sheet for head gasket torque sequence, torque values, and whether to retorque after heat cycle.
- Dry‑fit the major components (heads, rocker boxes, covers) to verify all gaskets and O‑rings in the kit are correctly identified before disassembly.
- Clean all gasket surfaces with a plastic scraper and non‑chlorinated brake cleaner; avoid Scotch‑Brite on aluminum sealing surfaces as it can embed abrasive.
- Chase head bolt and critical threaded holes, then blow out with compressed air so torque readings are accurate.
- Allow engine to fully cool after first heat cycle and inspect for weeping around head gaskets, rocker boxes, and cam cover.
Common Mistakes to Avoid
- Not checking head and cylinder deck surfaces for flatness before installing MLS/EST head gaskets
- Reusing factory torque specs and pattern but not following Cometic’s specific head gasket instructions (torque steps, retorque, dry vs lubricated threads)
- Using sealants where they are not specified (MLS head gaskets and many cover gaskets are designed to be installed dry)
- Improper surface preparation: leaving old gasket material or deep scratches that compromise sealing
- Incorrect pushrod adjustment or lifter pre‑load after reassembly, leading to noise or poor running
Comparison vs Stock/OEM
Compared to stock Harley‑Davidson gaskets, Cometic’s EST MLS head gaskets and premium materials provide improved sealing, especially on high‑compression and big‑bore Twin Cam engines.
Improvements
- Multi‑Layer Steel (MLS) EST head gaskets designed to better handle higher cylinder pressures and temperatures than many OEM composite gaskets.
- More complete kit coverage, including many small O‑rings and seals needed for comprehensive engine work.
- Higher resistance to fretting, micro‑leaks, and long‑term compression set.
Considerations
- Requires proper surface preparation and accurate torque procedure; less forgiving of warped surfaces than some OEM composite gaskets.
- Performance‑oriented—best results on straight, properly machined heads and cylinders.
Durability & Warranty
Expected Lifespan
Designed to last the life of a properly built Twin Cam top end under normal use; commonly used in high‑mileage touring and performance builds.
Warranty
Typical Cometic limited manufacturer warranty against defects in materials and workmanship (specific terms vary by seller and region).
Maintenance
No routine maintenance for the gaskets themselves; monitor for oil seepage at head, rocker, and cam cover areas during regular service intervals, especially after initial heat cycles.
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