Mikuni Jet Needle Leaner - 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.
This Mikuni jet needle for HSR42 carburetors features a leaner taper, specifically designed to reduce fuel delivery in the mid-range throttle range. It's a direct replacement component for Mikuni HSR42 carburetor assemblies on V-twin motorcycles, ideal for fine-tuning.
Why riders pick this
- Leaner taper for mid-range fuel reduction
- Direct Mikuni HSR42 replacement
- Optimizes fuel mixture in mid-range
- Helps correct rich running conditions
When your V-twin is running too rich in the mid-range, it can lead to poor fuel economy, sluggish response, and fouled plugs. This genuine Mikuni leaner jet needle allows you to precisely dial back the fuel flow, optimizing your HSR42 carburetor's performance. It's a critical adjustment for achieving a clean-burning, responsive engine.
Precise Fuel Reduction
- Leaner taper profile for HSR42 carburetors
- Reduces mid-range fuel delivery for optimal mixture
- Direct Mikuni OEM replacement for reliable fitment
- Helps correct overly rich conditions
Dialing in Your V-Twin Carb
Proper carburetor jetting is essential for maximizing power and efficiency from your Harley or Indian. If your bike exhibits signs of running rich in the mid-range—such as sputtering, black smoke, or excessive fuel smell—this leaner jet needle is often the solution. Integrating this needle into your tuning strategy ensures your HSR42 carburetor delivers the right amount of fuel at the right time, leading to a smoother running engine and better overall rideability.
Specifications
- Brand: Mikuni
- Manufacturer Part #: FJ8-8DDY01-98
- Length: 4.4 in
- Width: 1.9 in
- Height: 0.4 in
- Weight: 0.05 lbs
- Country of Origin: Japan
Common questions
What does a leaner jet needle do for my HSR42 carburetor?
A leaner taper on the jet needle reduces fuel flow in the mid-range throttle positions. This is useful for dialing out an overly rich condition that might occur between cruising speeds and wide-open throttle, improving engine performance and efficiency.
Is this jet needle compatible with my Mikuni HSR42 carburetor?
Yes, this is a direct Mikuni replacement part specifically designed for HSR42 carburetor assemblies. Always verify your exact carburetor model before making a purchase to ensure proper fitment.
Is the installation of this jet needle difficult?
Jet needle replacement typically involves removing the carburetor and accessing the needle clip located inside the slide. While not overly complex, some carburetor experience or a service manual is recommended to ensure correct installation and adjustment.
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 | 14-2507 |
| WEIGHT | 0.05 lb |
