Mikuni

Required when installing smooth-bore Mikuni carburetors HS 40 & HSR 42/45 on models with crankcase breathers that vent through the heads. Works with HSR 42/45 on Big Twin, Sportster and Buell models.

Since the seventies Mikuni round slide carbs were and still are installed on Harleys. They are robust, easy to adjust and fuel economical. This 34 mm version is specifically sized for 45 cui./750cc W and G (Servicar) models, where they replace that old Linkert and yield smooth idle, easy starting and crisp acceleration.

These 40 mm flat throttle slide carburetors are made by Mikuni and especially designed for Shovelhead and Evolution engines. The advantages of the popular ”HS40” carburetor are its easy installation, improved starting, more torque throughout the RPM range and fully adjustable accelerator pump.

The upgraded versions of the proven HS40 flat slide carburetor deliver optimized performance for high-output Harley-Davidson engines. The main difference from the predecessor is the enlarged intake bore, available in 42 mm and 45 mm diameters, which significantly increases cylinder filling. The 45 mm version is specifically designed for large-displacement engines from 98 cui upwards or for racing applications. Technical enhancements such as the two-piece flat slide running on precision stainless steel roller bearings ensure improved throttle response. A refined return spring offers smoother throttle operation and enhances rider comfort. Additional features include an idle mixture adjustment screw, enlarged needle valve, bigger float bowl, and an adjustable accelerator pump. The result: excellent starting behavior, powerful torque delivery, and enhanced rideability across the entire RPM range. Installation is straightforward with the included mounting and tuning instructions. The original Harley-Davidson choke cable remains compatible.

The upgraded versions of the proven HS40 flat slide carburetor deliver optimized performance for high-output Harley-Davidson engines. The main difference from the predecessor is the enlarged intake bore, available in 42 mm and 45 mm diameters, which significantly increases cylinder filling. The 45 mm version is specifically designed for large-displacement engines from 98 cui upwards or for racing applications. Technical enhancements such as the two-piece flat slide running on precision stainless steel roller bearings ensure improved throttle response. A refined return spring offers smoother throttle operation and enhances rider comfort. Additional features include an idle mixture adjustment screw, enlarged needle valve, bigger float bowl, and an adjustable accelerator pump. The result: excellent starting behavior, powerful torque delivery, and enhanced rideability across the entire RPM range. Installation is straightforward with the included mounting and tuning instructions. The original Harley-Davidson choke cable remains compatible.

The carburetors only. For Custom Bike projects. Designed to fit stock CV manifolds and air cleaners but accept various aftermarket air cleaners, too.

Complete selection of individual replacement parts for Mikuni cran case breathers.

O-Ring by Mikuni; for Idle air adjuster screw; Mikuni HSR 42 and 45 carburetor; rubber; ID x OD: 3 x 5 mm, 1 mm thick ; gross weight: 1 g

O-Ring by Mikuni; for Float valve; Mikuni HS 40 carburetor; rubber; Ø 10.5 mm; ID x OD: 7.5 x 10.5 mm, 1.5 mm thick; inner Ø: 7.5 mm; gross weight: 1 g

O-Ring by Mikuni; for Float valve; Mikuni HSR 42 and 45 carburetor; rubber; ID x OD: 8.5 x 11.5 mm, 1.5 mm thick; gross weight: 1 g

O-Ring by Mikuni; for Breather bolt / Banjo / Cylinder head; Mikuni HS 40 carburetor; rubber; ID x OD: 8.5 x 12.5 mm, 2.0 mm thick ; gross weight: 10 g

O-Ring by Mikuni; for Drain plug / Float bowl; Mikuni HS 40 carburetors, Mikuni HSR 42 and 45 carburetors; rubber; ID x OD: 19.5 x 22.5 mm, 1.5 mm thick ; gross weight: 8 g

O-Ring by Mikuni; for Adapter / Air cleaner; Mikuni HSR 42 and 45 carburetor; rubber; ID x OD: 66.6 x 77 mm, 5.2 mm thick ; gross weight: 10 g