Mikuni HSR 42, 45, and 48 Carburetor Kits for Harley Davidson Mikuni has followed up on its successful HS40 Carburetor with the advanced technology second generation performance carburetor called the HSR42. The designation HSR42 denotes a smoothbore racing carburetor with a 42mm venturi for Harley-Davidson applications. The HSR42 and its big brother the HSR45 were designed with a larger body assembly to fill the need for bigger throttle bores in all-out performance applications. Mikuni designed the new HSR42 carburetor with a smooth pulling 8-roller bearing flat throttle slide assembly. The flat throttle slide design allows an unobstructed venturi at full throttle to flow more air, and it carburetes more precisely at all throttle settings. Most aftermarket carburetors use butterfly throttle valves which obstruct the carburetor’s venturi at all throttle openings, creating airflow turbulence and hindering precise air/fuel metering. Mikuni’s roller bearing throttle slide offers smoother control and allows the use of a lighter throttle return spring for reduced throttle effort. Flow bench tests show that the new Mikuni HSR42 and HSR45 are able to flow more air to the engine once installed on the manifold and head than other models of aftermarket big-bore carburetors.
NOTE: Fits 1340cc Big Twin Evolution models 1984 thru 1999.
