Genuine Mikuni HSR Short Idle Adjuster Screw – Fits HSR42 / HSR45 / HSR48 Carburetors – Made in Japan

OVERVIEW

This Genuine Mikuni short idle adjuster screw restores precise throttle blade positioning and stabilizes engine idling after wear or damage affects the carburetor baseline. Machined from OEM-grade metal and manufactured in Japan, this direct-fit replacement matches factory tolerances to eliminate tuning drift. Designed specifically for Mikuni HSR series carburetors, it delivers immediate calibration accuracy without requiring extra tools or adapters.

ENGINEERING & PERFORMANCE

The precision-ground shaft provides smooth, repeatable idle calibration while maintaining consistent contact with the intake housing under high-vibration conditions. Solid OEM-grade metal construction resists cross-threading and surface degradation, keeping the critical thread pitch intact over thousands of adjustment cycles. When paired with correctly sized pilot components, this calibrated screw eliminates lean spikes and ensures stable low-speed throttle response across varying ambient temperatures.

KEY FEATURES

• Genuine Mikuni OEM replacement
• Smooth and precise idle adjustment capability
• Correct thread pitch tailored for HSR-series designs
• Made in Japan to maintain strict manufacturing standards
• Prevents tuning instability caused by stripped adjusters
• Direct replacement for damaged or entirely missing screws
• Compatible with HSR42, HSR45, and HSR48 models
• High-precision mechanical finishing meets factory specifications

TECHNICAL SPECIFICATIONS

• Brand: Genuine Mikuni
• Part Name: Short Idle Adjuster Screw
• Material: OEM-grade metal construction
• Construction Origin: Made in Japan
• Compatibility: HSR42, HSR45, HSR48 carburetors

FITMENT

• Mikuni HSR42 carburetor
• Mikuni HSR45 carburetor
• Mikuni HSR48 carburetor

WHY RIDERS CHOOSE THIS

Custom builders and vintage-performance enthusiasts favor this Mikuni adjuster because it restores exact airflow metering without trial-and-error modifications. The hardened metal shaft prevents the stripping common with cheap aftermarket copies, ensuring that weekly tuning adjustments never compromise structural integrity. By holding a steady baseline at low RPM, it significantly reduces stalling and sharpens throttle tip-in on machines running direct-mount HSR units. Replacing a flawed factory part with this precision-made screw guarantees predictable engine behavior whether tackling trail riding or heavy-load cruising.