Kubota KX121-3

Parts Compatible with the Kubota KX121-3 Mini Excavator

The KX121-3 is the 5 ton class entry in Kubota's legacy 3 Series mini excavator lineup, sitting between the smaller KX91-3 (4 ton class) and the larger KX161-3 (5+ ton class) in the same generation. Production ran through the early to mid 2010s before the platform was replaced by the current 4 Series machines (KX040-4 in the 4 ton class and KX057-4 in the 5 ton class). The base KX121-3 designation covers the open station ROPS canopy machine, with the -S, -SC, -SCA, -ST, and -STCA suffixes indicating cabin and Canadian spec variants. The cabin variants share the same drivetrain, hydraulics, and engine as the open station base, but add cab glass, HVAC components, and a different operator console.

Many KX121-3 parts cross to the larger KX161-3 in the same generation because Kubota used common engines, common hydraulic pumps, and a similar cab structure across the two model sizes. The V2203 engine in the KX121-3 also powers other Kubota equipment, which means engine service parts (oil filters, fuel filters, water pump, glow plugs) cross widely outside the KX product line. Cab glass on the KX121-3 uses the RC411 series dimensions, which is unique to this 3 Series cab generation and does not interchange with the newer 4 Series cabs (KX040-4, KX057-4) that use the RD451 series dimensions.

Common Replacement Parts for the Kubota KX121-3

Cab glass is one of the most-ordered KX121-3 replacement categories. Lower Door Glass RC411-46540, Upper Door Glass RC411-46530, Right Hand Sash Glass RC411-46710, Front Lower Glass RC411-46330, and Front Upper Glass RC411-46112 cover the cab glass replacement set. Inner Air Filter R240142289 is the safety element that pairs with the primary canister on the KX121-3 air cleaner. Cab Air Filter 6A671-75090 covers the climate controlled cab variants. Engine cooling and pump service uses Water Pump 1A051-73410, Water Pump 1A051-73030 (older revision), and Thermostat Assembly 1A021-73012. Fuel Filter RA211-51280 fits the V2203 fuel system, with Solenoid 1A021-60013 covering the engine stop solenoid. Starter motor 17123-63016 is a common service replacement on machines past 5,000 hours. Smaller assembly hardware including Oil Gauge Plug 1G513-36550, Oil Switch 15531-39010, Guide Oil Gauge 17456-36420, O-Ring 04811-50550, O-Ring 04817-50300, and Shim RD451-19180 rounds out routine service.