Czsmbt CV40 Carburetor for Harley‑Davidson Sportster 883/1200 (1988–2006) — Vacuum‑Diaphragm & Accelerator Pump

If your older Harley is experiencing flat spots, hesitation, or inconsistent idle, the Czsmbt CV40 carburetor is a direct-fit replacement designed to restore predictable fueling on many Sportster, Dyna, Softail, FXR and Touring models from 1988 through the mid‑2010s. This aftermarket unit uses a vacuum‑diaphragm design for automatic airflow metering and includes practical hardware so you can install and tune it for a reliable ride.

Which Harley models and part numbers does this CV40 fit?

This carburetor covers a wide range of Harley-Davidson models and several OEM part cross-references. Always verify your motorcycle's year and original equipment numbers before ordering to ensure compatibility.

• Fitment: Sportster 883/1200 (XL/XLH series) 1988–2006, Heritage Softail 1988–2017, Dyna & FXR 1988–2016, Touring 1988–2016.
• Interchangeable OEM references include 27412‑99, 27421‑99A, 27421‑99C, 27490‑04, 27465‑04, 27031‑95, 27490‑96.
• Confirm by checking your bike's carburetor style and throttle/airbox connections prior to purchase.

How does the vacuum‑diaphragm design affect throttle behavior?

The vacuum‑diaphragm automatically adjusts airflow metering based on engine vacuum, helping to prevent bogging during sudden throttle openings. Combined with the accelerator pump, it reduces hesitation and improves acceleration response without rider input for the choke or manual adjustments.

• Vacuum‑diaphragm actuation smooths transient fueling during abrupt throttle changes.
• Built‑in accelerator pump supplies immediate fuel enrichment to limit flat spots.
• Includes factory‑style main and slow jets to match typical stock setups (stock #170 main, #45 slow).

What hardware and protections are included in the package?

The carburetor ships with installation and tuning components so you can replace the unit and perform basic jetting adjustments right away. Added features like an overflow drain nipple help prevent excess fuel from entering the intake tract in case of float problems.

• Package contents: carburetor, two fuel lines, one fuel filter, brush set, two spark plugs, three main jets (#180, #185, #190), three slow jets (#42, #45, #48).
• Factory stock jets included (#170 main, #45 slow) for baseline tuning.
• Overflow drain nipple disposes of excess fuel to reduce flooding risk.

Can I tune this carburetor for different riding conditions?

Yes — the supplied extra jets make initial tuning straightforward for common elevations and fuel blends. Use the additional main and slow jets to refine air/fuel balance for improved throttle response, mileage, or power delivery based on local conditions.

• Swap main jets (#180, #185, #190) to lean or richen top‑end fueling as needed.
• Use slow jets (#42, #45, #48) to dial idle and low‑throttle response.
• Basic tuning can be done with the included parts; professional dyno tuning recommended for precise performance setups.

Who is this for: Riders restoring or maintaining older Harley-Davidson motorcycles who want a practical, direct-fit carburetor replacement that balances plug‑and‑play convenience with room for tuning. This unit suits owners replacing worn stock carbs, updating a bike for better throttle feel, or preparing a machine for regular road use. Czsmbt backs the product with a one‑year service promise offering refund or replacement if you’re not satisfied.