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Start ShoppingCometic C9277 Evo Big Twin Rocker Box Gasket Set - High-Performance AFM Gasket Kit for Harley-Davidson
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Description
Upgrade your Harley-Davidson Evolution Big Twin's engine performance with Cometic's C9277 rocker box gasket set. This complete top-end gasket kit delivers exceptional sealing reliability and long-lasting durability for high-performance riding.
Key Features
- AFM Aluminum Foam Material: Advanced re-usable technology provides superior heat resistance and maintains sealing integrity through multiple heat cycles.
- Complete Rocker Box Kit: Includes upper, middle, and lower gaskets plus seals for both cylinders - no need for partial replacements.
- Heavy-Duty Construction: Premium fiber and rubber-coated steel components withstand extreme engine temperatures and pressures.
- Harley-Davidson Specific Fitment: Engineered for Evolution Big Twin models to ensure perfect alignment and leak-free operation.
- USA-Made Quality: Manufactured in the USA with precision engineering for maximum performance and reliability.
Why Choose This Product
Cometic's C9277 gasket set combines cutting-edge AFM technology with durable materials to deliver unmatched sealing performance. The re-usable design eliminates the need for re-torquing after heat cycles, saving time and effort during maintenance. As a complete kit, it ensures comprehensive coverage for both cylinders, reducing the risk of leaks and engine damage. Built for Harley-Davidson's Evolution Big Twin engines, this gasket set maintains optimal compression and performance while withstanding the rigors of powersports use. Its premium materials provide long-term durability, making it a trusted choice for riders who demand reliability from their motorcycles.
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Upgrade your Harley-Davidson Evolution Big Twin's engine performance with Cometic's C9277 rocker box gasket set. This complete top-end gasket kit delivers exceptional sealing reliability and long-lasting durability for high-performance riding.
Key Features
- AFM Aluminum Foam Material: Advanced re-usable technology provides superior heat resistance and maintains sealing integrity through multiple heat cycles.
- Complete Rocker Box Kit: Includes upper, middle, and lower gaskets plus seals for both cylinders - no need for partial replacements.
- Heavy-Duty Construction: Premium fiber and rubber-coated steel components withstand extreme engine temperatures and pressures.
- Harley-Davidson Specific Fitment: Engineered for Evolution Big Twin models to ensure perfect alignment and leak-free operation.
- USA-Made Quality: Manufactured in the USA with precision engineering for maximum performance and reliability.
Why Choose This Product
Cometic's C9277 gasket set combines cutting-edge AFM technology with durable materials to deliver unmatched sealing performance. The re-usable design eliminates the need for re-torquing after heat cycles, saving time and effort during maintenance. As a complete kit, it ensures comprehensive coverage for both cylinders, reducing the risk of leaks and engine damage. Built for Harley-Davidson's Evolution Big Twin engines, this gasket set maintains optimal compression and performance while withstanding the rigors of powersports use. Its premium materials provide long-term durability, making it a trusted choice for riders who demand reliability from their motorcycles.| SKU | GM8918508B |
|---|---|
| MPN | C9277 |
| Brand | Cometic |
| Category | Gaskets/Seals |
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Featured Review
| Make | Model | Years |
|---|---|---|
| Harley-Davidson | FXR / FXRS / FXRT / FXRP (Evo Big Twin models) | 1984-1991 |
| Harley-Davidson | Softail models with Evolution Big Twin | 1986-1999 |
| Harley-Davidson | FLH/FLHT/FLHR/FLHS/FLT/FLHTC/FLHTCU (Touring with Evo Big Twin) | 1984-1998 |
| Harley-Davidson | Dyna models with Evolution Big Twin | 1991-1998 |
Frequently Asked Questions
C9277 is designed specifically for Harley‑Davidson Evolution Big Twin (1340cc) engines and does not fit Twin Cam or Milwaukee‑Eight engines.
Yes. C9277 includes the rocker box gaskets and related seals needed to service both front and rear rocker boxes on an Evo Big Twin.
Cometic’s AFM style gaskets can often tolerate some disassembly, but they are sold and recommended as single‑use parts for best sealing and reliability.
In most cases no extra sealant is required on the gasket surfaces themselves. Follow the Harley‑Davidson service manual; a small amount of sealant may be recommended only at specific joints or corners.
Yes, provided the mating surfaces are flat and properly torqued, replacing old, hardened gaskets with a quality kit like Cometic C9277 is a common fix for rocker box oil leaks on Evo Big Twins.
Installation Guide
Difficulty
Medium
Est. Time
2 hr 0 min
Tools Required
- SAE socket set
- Allen/hex sockets (Harley rocker box fasteners)
- Torque wrench (inch‑lb and ft‑lb)
- Combination wrenches
- Scraper or plastic razor blade for old gasket removal
- Brake cleaner or solvent
- Shop rags
- Service manual for torque sequence
Pro Tips
- Work on a cold engine to avoid warping components and burning yourself.
- Clean all mating surfaces thoroughly and check rocker boxes and heads for nicks; lightly dress any high spots.
- Follow the factory torque pattern in several small steps rather than going straight to final torque.
- Check pushrod adjustment (if adjustable pushrods are fitted) after reassembly.
- After first ride, visually inspect for seepage around the rocker boxes.
Common Mistakes to Avoid
- Over‑torquing rocker box bolts and distorting the gasket
- Failing to completely remove old gasket material and sealant
- Not following the correct torque sequence from the service manual
- Re‑using old, flattened rocker gaskets instead of installing the full set
- Installing gaskets dry where the manual calls for light oil on specific seals
Comparison vs Stock/OEM
Comparable or higher sealing performance than OEM rocker box gaskets, using premium AFM and composite materials.
Improvements
- Better long‑term resistance to heat and compression set versus many economy aftermarket gaskets
- Frequently reported to reduce weeping and seepage common with older Evo rocker boxes
- Made in USA with performance‑oriented materials used in racing applications
Considerations
- Must follow proper surface prep and torque procedure; the gasket alone will not fix warped or damaged rocker boxes or heads.
Durability & Warranty
Expected Lifespan
Typically lasts many years and tens of thousands of miles when installed on flat, undamaged surfaces and torqued correctly.
Warranty
Standard Cometic limited warranty against defects in materials and workmanship (terms vary by seller).
Maintenance
No periodic maintenance required; inspect for leaks during regular oil changes. Replace gaskets if rocker boxes are removed or if leakage develops.
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