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Start ShoppingCOMETIC C9509 MLS Seal - Premium Gasket for Panhead/Shovelhead/Evo Big Twin Engines
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Description
Upgrade your Harley-Davidson or Triumph engine's sealing system with COMETIC's premium MLS gasket. Designed for Panhead, Shovelhead, and Evo Big Twin models, this seal ensures optimal compression, reduced oil leaks, and enhanced engine longevity for riders demanding top performance.
Key Features
- Multi-Layer Steel (MLS) Construction: Superior heat resistance and durability for high-performance engines.
- 3.437 in. Bore Size (87.30 mm): Precision-fit for original equipment specifications.
- 0.040 in. Compressed Thickness: Ensures proper sealing without excessive engine compression.
- 1 Gasket per Pack: Ideal for direct replacement and budget-friendly maintenance.
- Lightweight Design (0.1 lbs): Easy installation without compromising structural integrity.
Why Choose This Product
COMETIC's C9509 seal combines advanced MLS technology with precise engineering to deliver unmatched sealing performance. Its reinforced construction prevents oil leaks and maintains compression efficiency, while the exact bore size ensures compatibility with original equipment. Riders will appreciate the hassle-free installation and long-term reliability, making it a must-have for maintaining peak engine performance on classic and modern Big Twin models.
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Upgrade your Harley-Davidson or Triumph engine's sealing system with COMETIC's premium MLS gasket. Designed for Panhead, Shovelhead, and Evo Big Twin models, this seal ensures optimal compression, reduced oil leaks, and enhanced engine longevity for riders demanding top performance.
Key Features
- Multi-Layer Steel (MLS) Construction: Superior heat resistance and durability for high-performance engines.
- 3.437 in. Bore Size (87.30 mm): Precision-fit for original equipment specifications.
- 0.040 in. Compressed Thickness: Ensures proper sealing without excessive engine compression.
- 1 Gasket per Pack: Ideal for direct replacement and budget-friendly maintenance.
- Lightweight Design (0.1 lbs): Easy installation without compromising structural integrity.
Why Choose This Product
COMETIC's C9509 seal combines advanced MLS technology with precise engineering to deliver unmatched sealing performance. Its reinforced construction prevents oil leaks and maintains compression efficiency, while the exact bore size ensures compatibility with original equipment. Riders will appreciate the hassle-free installation and long-term reliability, making it a must-have for maintaining peak engine performance on classic and modern Big Twin models.
| SKU | GM35383822 |
|---|---|
| MPN | C9509 |
| Brand | Cometic |
| Category | Gaskets/Seals |
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Featured Review
| Make | Model | Years |
|---|---|---|
| Harley-Davidson | Big Twin (Panhead, Shovelhead) | 1948-1984 |
| Harley-Davidson | Evolution Big Twin | 1984-1999 |
Frequently Asked Questions
C9509 is for stock 3.437 in. bore. For stroker/big bore, check Cometic part C9613 or similar for larger bores.
Multi-layer steel (MLS) for superior sealing under high compression and heat.
Recommended to have heads checked for flatness (max 0.004 in. warp). MLS gaskets tolerate minor imperfections better than composite.
0.040 in. is standard; for higher compression, consider thinner 0.030 in. options like C9610.
Installation Guide
Difficulty
Medium
Est. Time
45 min
Tools Required
- torque wrench
- gasket scraper
- head bolt socket set
- feeler gauges
Pro Tips
- Clean surfaces with brake cleaner, no residue. Use assembly lube on bolts. Torque in criss-cross pattern to spec (typically 35-45 ft-lbs for Big Twin heads). Verify compression thickness post-install.
Common Mistakes to Avoid
- Not cleaning mating surfaces thoroughly
- Incorrect torque sequence
- Over-torquing bolts
Comparison vs Stock/OEM
OEM is typically paper/composite; Cometic MLS is metal-reinforced
Improvements
- Better heat resistance
- Improved sealing on imperfect surfaces
- Handles higher compression (up to 12:1)
Considerations
- More rigid; requires precise torque
Durability & Warranty
Expected Lifespan
Engine rebuild lifespan (50,000+ miles with proper install)
Warranty
1 year manufacturer defect warranty
Maintenance
Inspect during valve adjustments; re-torque head bolts after 500 miles
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