Mikuni Jet Needle Richer - HSR42 Carburetor
About Mikuni
Mikuni has supplied carburetors and fuel-system components to the motorcycle industry for decades, and its HSR series remains a common choice for carbureted Evolution and Twin Cam V-twins where a clean, tunable fuel curve matters more than electronics.
Achieve precise fuel metering with this Mikuni jet needle, designed with a richer taper profile for HSR42 carburetors. It's an essential component for dialing in your V-twin's fuel mixture, especially when adjusting for mid-range and full-throttle performance.
Why riders pick this
- Richer taper profile for HSR42 carbs
- Adjusts mid-range to full-throttle fueling
- Direct Mikuni OEM replacement
- Essential for V-twin carb tuning
The jet needle is crucial for controlling fuel flow at various throttle positions on your carbureted Harley or Indian. This genuine Mikuni replacement needle features a richer taper, allowing you to fine-tune the fuel mixture in the mid-range and at full throttle. It's a key part of resolving lean conditions that can arise from performance upgrades.
Enhanced Fuel Control
- Richer taper profile for Mikuni HSR42 carburetors
- Direct replacement for seamless installation
- Adjusts mid-range to full-throttle fuel mixture
- Helps address lean running conditions
Precision Tuning for Your V-Twin
Optimizing your carburetor's jetting ensures your engine performs efficiently and reliably. Installing a richer jet needle can be a vital step if your V-twin is running lean at cruising speeds or wide-open throttle, often indicated by hesitation or excessive heat. This needle allows for a more robust fuel delivery, contributing to smoother operation and potentially increased power output when paired with proper tuning.
Specifications
- Brand: Mikuni
- Manufacturer Part #: FJ8-8DDY01-96
- Length: 4.4 in
- Weight: 0.05 lbs
- Country of Origin: Japan
Common questions
What does a richer jet needle taper do?
A richer taper profile on the jet needle adds more fuel to the mixture in the mid-range and at full-throttle positions. This is beneficial if your carburetor is running too lean in those ranges, often after installing performance parts.
Will this jet needle fit other Mikuni carburetor models?
No, this jet needle is specifically designed and tapered for Mikuni HSR42 carburetors only. Other Mikuni models require different jet needles for proper fitment and function.
Do I need to re-jet my carburetor after installing this needle?
The jet needle primarily controls fuel delivery in the mid-range and top-end. While it's a significant tuning component, main and pilot jets control low-speed and wide-open throttle mixtures separately. A full carburetor tune may still be necessary to balance all fuel circuits.
Ordering from Vtwinbikers
- Brand new, sourced through authorized US distribution — never used, never grey-market.
- Not sure it fits? Use Shop by Bike to filter by your year and model, or email us and we will confirm before you order.
- Harley-Davidson and Indian Motorcycle is all we do, so you are talking to people who ride what you ride.
| BRAND | Mikuni |
| TYPE | Intake/Carb/Fuel System |
| SKU | 14-2505 |
| WEIGHT | 0.05 lb |
