High-quality digital replica of the often-cracked, warped, or impossible-to-find carburetor top cover (vacuum chamber cap) for the legendary Mikuni BST33 constant velocity (CV) carburetor.As these motorcycles age, the original plastic/bakelite caps suffer from heat cycles and fuel vapor, leading to hair-cracks, vacuum leaks, and ruined cylinder equalization. This precision-engineered 3D model allows you to print a perfect, smooth replacement to restore your engine's performance.This is a clean, smooth version (no logos) designed for maximum stealth and compatibility.

What You Get (Digital Download)

• STL File: Optimized and ready to slice for 3D printing
• STEP File: High-fidelity CAD format for easy modification, CNC machining, or engineering adjustments.

Technical Specifications & Verification

• Carburetor Model: Mikuni BST33 (33mm Venturi internal bore size).
• Cap Outer Fitting Diameter: 62mm at the base where it seals the rubber diaphragm to the carburetor body.
• Please measure the top flange of your carburetor before purchasing to ensure a 100% accurate match.

Confirmed Bike Compatibility

• This cover fits any motorcycle utilizing the Mikuni BST33 carburetor assembly, including:

• Suzuki GS 500 / GS 500E / GS 500F (All years)

• Suzuki DR 350 / DR 250S

• Suzuki DR 750 / DR 800 (Dr. Big)

• BMW F650 Funduro / ST (Years 1994 – 2000, Dual Carb setup)

• Aprilia Pegaso 650 (Years 1992 – 2000)

3D Printing Recommendations (Crucial for Engine Bay Use)

• Because this part operates near engine heat and is exposed to fuel vapors, DO NOT USE PLA.
• Recommended Filaments: ASA, ABS, Nylon (PA), or PETG (at a minimum). ASA is highly recommended due to its superior UV, heat, and chemical resistance.
• Infill: 100% solid infill (or minimum 60% with thick walls) to ensure absolute airtight vacuum seal.

• Perimeters/Walls: 4 to 5 perimeters.

• Post-Processing: Lightly sand the 62mm mating surface on a flat piece of sandpaper to ensure a perfect, airtight seal against the carburetor body.

Disclaimer: This is a digital file download only. No physical product will be shipped. Due to the nature of digital products, all sales are final.