2000 Road King Fuel Injection Line Upgrade: What You Need to Know
The 2000 Harley-Davidson Road King came from the factory with a carbureted engine — specifically the Twin Cam 88 paired with a CV carburetor. So when riders talk about a "fuel injection line upgrade" on this bike, they're usually referring to one of two very different projects: converting the carbureted system to fuel injection, or upgrading existing fuel delivery lines on a bike that's already been converted or modified. Understanding which path you're on shapes everything about parts, cost, and complexity.
How the 2000 Road King Fuel System Was Originally Built
From the factory, the 2000 Road King used a Keihin CV (constant velocity) carburetor to mix air and fuel. Fuel traveled from the tank through rubber fuel lines to the carb, relying on gravity and vacuum — no fuel pump pressure, no injectors, no ECU.
Harley didn't introduce fuel injection as a standard feature on the Road King until the 2007 model year. Earlier models, including the 2000, require an aftermarket EFI conversion if you want injection — and that's a significant undertaking.
What a Fuel Injection Conversion Actually Involves
A full EFI retrofit on a carbureted Road King typically includes:
- Throttle body and injector assembly replacing the carburetor
- Fuel pump (carbureted systems don't have one; injection systems require a pressurized pump, usually mounted in or near the tank)
- High-pressure fuel lines rated for injection system pressures (typically 40–60 PSI, compared to near-zero pressure in carb-fed systems)
- ECU or fuel management module to control injector timing and fuel mapping
- Wiring harness modifications or additions
- Fuel pressure regulator and return line in many setups
The fuel lines used in a carburetor system are not compatible with EFI pressures. Swapping in injection-rated lines — typically reinforced rubber or braided stainless steel with proper AN or push-lock fittings — is a required part of any legitimate conversion, not an optional upgrade.
Upgrading Fuel Lines on an Already-Converted Bike 🔧
If your 2000 Road King has already been converted to EFI by a previous owner, you may be looking at upgrading aging or substandard fuel lines. Common reasons riders pursue this:
- Original conversion used low-quality lines that are starting to crack, seep, or swell
- Braided stainless lines offer a cleaner look and better abrasion resistance
- Rubber lines deteriorate over time, especially when exposed to ethanol-blended fuels
- Routing issues from a non-standard conversion need to be corrected
In this context, "fuel injection line upgrade" usually means replacing the high-pressure feed line, return line (if applicable), and associated fittings with higher-quality components better suited to sustained injection pressures.
Key Variables That Affect This Project
No two EFI setups on a converted Road King are exactly the same. What you're working with depends on:
| Variable | Why It Matters |
|---|---|
| Conversion kit brand/type | Determines fuel pressure range, fitting sizes, and line routing |
| Tank configuration | Some setups mount the pump inside the tank; others use an external inline pump |
| Return vs. returnless system | Return-style EFI requires two lines; returnless requires one |
| Fuel blend compatibility | E10/E15 fuels degrade some rubber compounds faster |
| Line diameter and fittings | Must match the fuel pump outlet and throttle body inlet specs exactly |
| Bike's current wiring | Matters if you're doing a full conversion vs. just swapping lines |
Getting the line diameter, pressure rating, and fitting type wrong can cause fuel leaks — a serious safety issue on any motorcycle.
DIY vs. Professional Installation
Replacing or upgrading fuel lines on a carbureted bike is considered a moderate DIY task. On an EFI-converted Road King, the complexity goes up:
- High-pressure fuel systems require leak-free connections. A fitting that's slightly mismatched or undertightened can leak at idle but fail catastrophically under load.
- Braided stainless lines require proper crimping or AN fittings — not all riders have the tools or experience to assemble these correctly.
- Full EFI conversions are generally considered intermediate-to-advanced work and often benefit from a shop that specializes in Harley performance builds.
Labor costs for fuel system work vary widely by region and shop type. Independent Harley specialists, dealerships, and general powersports shops all price this work differently.
Fuel Line Material Choices
Rubber lines are the most common and least expensive option. When rated for EFI pressures and ethanol-compatible materials (look for SAE J30 R9 spec or equivalent), they perform reliably. The downside is degradation over time, particularly with higher ethanol blends.
Braided stainless steel lines with AN fittings are popular in the custom Harley market for both durability and aesthetics. They resist abrasion, look clean on a show-quality build, and hold up well to heat. They cost more and require care during installation to avoid kinking or cross-threading fittings.
PTFE-lined hose (sometimes called Teflon-lined) offers excellent chemical resistance and is a good middle ground — flexible, fuel-compatible, and available in braided versions. ⚙️
What Makes This Job Different on an Older Bike
A 2000 Road King has over two decades of exposure to heat cycles, vibration, and fuel blends that didn't exist when it was built. If you're working on a conversion or line upgrade today, it's worth inspecting:
- The fuel tank interior for rust or sediment that could clog injectors
- Any rubber grommets or check valves added during a prior conversion
- The condition of the fuel pump and filter if the bike was converted years ago
The age of the bike doesn't make this impossible — plenty of 2000-era Road Kings run clean EFI setups — but it does mean the full picture of what you're working with matters more than on a newer platform. What the previous owner used, how it was installed, and what condition it's in now are variables only a hands-on inspection can answer. 🛠️