Replacement Billet Head Domes for Polaris (800 / 850 / 900)

SKU: 04-311-800-41
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$90.00 USD
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Replacement Billet Head Domes for Polaris (800 / 850 / 900)

Tune your engine's compression ratio for optimal horsepower and elevation with Bikeman Performance Replacement Billet Head Domes for Polaris snowmobiles. Designed to fit seamlessly into Bikeman Modular Billet Head shells, these interchangeable domes allow you to quickly alter combustion chamber volume to suit changing mountain elevations, high-octane race fuels, or low-elevation pump gas setups without replacing your entire head assembly.

Each dome is CNC-machined with Bikeman’s custom squish band profile and combustion chamber geometry, promoting efficient flame propagation, lower engine operating temperatures, and superior detonation (DET) suppression on hard pulls.

Key Performance Features

  • Modular Compression Tuning: Easily swap domes to adapt your machine for low-elevation trail riding or high-altitude mountain trips.

  • Optimized Combustion Geometry: Engineered with custom squish band angles to increase horsepower while reducing detonation hot spots.

  • Precision CNC Machined: Crafted from high-grade aluminum for exact volume consistency across cylinders and maximum thermal dissipation.

  • Direct Fit Replacement: Drop-in replacement domes engineered exclusively for Bikeman Performance Polaris Billet Head Shells.

Available Dome Options & Part Numbers

  • Polaris 800 Domes

    • Low Altitude (41cc): Part #: 04-311-800-41
    • High Altitude (37.5cc): Part #: 04-311-800-37.5

  • Polaris 850 Domes

    • Low Altitude (40.5cc / 11.8:1 Comp): Part #: 04-318-850-40.5
    • High Altitude (36.5cc / 12.5:1 Comp): Part #: 04-318-850-36.5

  • Polaris 900 / 9R / Big Bore Domes

    • Low Altitude / Pump Gas (42cc): Part #: 04-318-900-42
    • High Altitude / Race Fuel (37cc): Part #: 04-318-900-37

Ordering & Pricing Information

  • PRICING NOTE: Price is PER DOME. (To replace domes for a complete 2-cylinder engine head, you must purchase a quantity of 2).

  • Compatibility: Fits Bikeman Performance Polaris Billet Cylinder Heads ONLY (Does not fit stock OEM single-piece heads).