This article details the installation process and compatibility information for the Rivera-Mikuni HSR42 carburetor kits. These kits are designed for specific Harley-Davidson motorcycle models and offer potential performance improvements. The following information is based on provided documentation and installation guides.
Compatibility and Applications
Rivera-Mikuni HSR42 carburetor kits are specifically designed for 1970-1984 Harley-Davidson “Shovelhead” BigTwin and 1971-1985 Iron Head XL motorcycles. The kits include the intake manifold, necessary hardware, and a high-performance Mikuni/K&N air filter. A crucial component for a successful installation is the use of 1990-1995 style throttle cables. The documentation notes that alternate tuning settings may be required depending on modifications to the Harley-Davidson engine. The carburetor kit is also compatible with Echo Pe-2000, Pe-2400, Gt-2000, Gt-2400, Srm-2100, Shr-210, Shc-1700, and Shc-2100 garden chainsaw models, utilizing a C1u-k52 or C1u-k47 carburetor.
Disassembly Procedure
Prior to installation, the existing carburetor must be removed. The recommended disassembly procedure includes the following steps:
- Disconnect the negative terminal of the motorcycle battery.
- Turn the fuel petcock to the “off” position.
- Remove the gas tank(s) from the motorcycle or elevate the rear of the tank(s) to improve access to the cylinder/intake manifold area.
- Remove the air cleaner assembly, including the backing plate.
- Disconnect the choke cable from the motorcycle.
- Disconnect any vacuum hoses and the fuel supply hose connected to the carburetor.
- Remove the existing carburetor from the motorcycle.
- Remove the existing throttle cables. It is important to note that 1990-1995 OEM style throttle cables are required for this installation.
Installation Procedure
The installation process involves several steps, beginning with the intake manifold.
- Intake Manifold Installation: Attach the provided rubber flange to the Rivera intake manifold using two 5/16" x ¾" bolts and flat washers. Then, attach the Mikuni intake manifold assembly to the engine heads, replacing the stock intake manifold. It is advised not to fully tighten the clamps at this stage, as final alignment will occur after the air cleaner assembly is installed. Special adapter rings are included for use on the intake manifold, enabling compatibility with “rubber-band” style manifold seals and larger intake configurations.
- Carburetor Mounting: Install the new Mikuni HSR42 carburetor onto the motorcycle, ensuring a secure fit using the included gaskets and mounting hardware.
- Fuel Line Connection: Reconnect the fuel line to the newly installed carburetor.
- Throttle and Choke Cable Connection: Connect the throttle and choke cables to the carburetor.
- Air Cleaner Assembly: Reinstall the air cleaner assembly onto the motorcycle.
- Battery Reconnection: Reconnect the motorcycle battery.
Post-Installation Checks and Adjustments
After installation, several checks and adjustments are necessary to ensure proper operation.
- Leak Check: Start the motorcycle and carefully inspect for any fuel leaks. If leaks are detected, tighten the fuel line connections.
- Idle Speed Adjustment: Adjust the idle speed screw on the carburetor to achieve the desired idle RPM.
- Mixture Adjustment: Adjust the mixture screw(s) on the carburetor to optimize fuel delivery and engine performance.
- Test Ride: Conduct a test ride to verify the carburetor is functioning correctly and the engine is performing as expected.
Benefits of the Mikuni HSR42 Pumper Carb
The Mikuni HSR42 HSR45 HSR48 Pumper Carb is designed to offer several performance benefits. These include improved throttle response, increased power output, and improved fuel economy. However, it is recommended that installation be performed by a professional mechanic, particularly for those with limited mechanical experience.
Maintenance Recommendations
Proper maintenance is crucial for ensuring the longevity and optimal performance of the Mikuni HSR42 carburetor. The following maintenance tips are recommended:
- Air Filter Maintenance: Regularly check and clean the air filter to prevent debris from clogging the carburetor.
- Periodic Inspection: Inspect the carburetor periodically for any signs of wear or damage.
- Adjustment as Needed: Adjust the carburetor as needed to maintain optimal fuel delivery and engine performance.
- Fuel and Oil Quality: Use high-quality unleaded gasoline and oil to avoid clogging or damaging the carburetor.
Important Considerations
Several important considerations should be noted during and after installation.
- California Compliance: Carburetor kits not designated as C.A.R.B. (California Air Resources Board) exempt are not legal for use on motor vehicles operated on public highways in California, or in any other states or countries with similar regulations.
- Engine Modifications: Since many Harley-Davidson engines are often highly modified, alternate tuning settings may be required to achieve optimal performance. The Mikuni HSR Tuning Manual can assist with jetting alterations and adjustments.
- Electrical Safety: Disconnecting the battery before beginning the installation process is crucial to avoid any electrical issues.
- Professional Installation: While the installation process is relatively straightforward, consulting a professional mechanic is recommended, especially for those unfamiliar with carburetor installation.
Frequently Asked Questions
Several frequently asked questions regarding the Mikuni HSR42 HSR45 HSR48 Pumper Carb are addressed in the provided documentation.
- Suitable Motorcycle Type: The Mikuni HSR42 HSR45 HSR48 Pumper Carb is suitable for Harley Evo Twin Cam Sportster 883 Tour Glide Softail models.
- Fuel Type: The carburetor is designed to use unleaded gasoline.
- Installation Difficulty: Installation requires basic mechanical skills and knowledge, and professional installation is recommended.
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Conclusion
The Rivera-Mikuni HSR42 carburetor kit offers a potential upgrade for specific Harley-Davidson and garden chainsaw models. Successful installation requires careful adherence to the provided disassembly and installation procedures, along with post-installation checks and adjustments. Maintaining the carburetor through regular inspection and cleaning will ensure optimal performance and longevity. It is important to verify compatibility with local emissions regulations and consider professional installation if mechanical experience is limited.