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Champion Spark Plug (RC12YC). The spark plug ignites the fuel and air mixture in the cylinder to power the engine. If the spark plug is burnt, fouled or damaged the engine may not start or may run rough.

Bow Tie Cotter Pin

Honda air cleaner (or air filter). If the air filter is clogged or dirty, the engine may not start or may run rough.

Fuel bowl gasket

Small engine Champion spark plug (RJ19LM). If the engine does not start, the spark plug may be defective. The spark plug should be replaced periodically during regular maintenance.

Genuine MTD 742-0305A-0637 Articulating Roto-Tiller Tine

Fuel Tank Kit

MTD Spark Plug. The spark plug ignites the fuel and air mixture in the cylinder to power the engine. If the spark plug is burnt, fouled or damaged the engine may not start or may run rough.

Carburetor gasket

Fuel cap assembly

Carriage Bolt: 5/16-18 x .750"

Replacement clutch kit

Self-tapping screw. 5/16-18 inches by .75 inches.

MTD flange lock nut, 5/16-18.

Two cycle engine carburetor. If the engine runs rough, the carburetor may be restricted. The carburetor can often be cleaned or rebuilt, but sometimes it may need to be replaced.
For serious garden enthusiasts, a Yard Machines tiller, like the 21AA404B000 model with an 18-inch till width and a 205cc Briggs and Stratton OHV engine, is what's required to get the job done right. To keep your tiller on the job for this season and the next, you're going to need genuine manufacturer replacement parts and that's what you'll find at Repair Clinic. From spark plugs and carburetor parts, to tines, throttle levels, and control cables, we can quickly ship you the specific MTD parts that match your Yard Machines tiller. To get started, enter the full model number of your equipment in our website's search bar to see a complete list of compatible parts. You can then refine that list down to the exact part you want by using the part category and part title filters.Use the online parts finder and model number lookup for exact part identification. Repair Clinic is about more than matching parts to specific outdoor power equipment, appliance, and heating and cooling product models. Our extensive DIY content library features thousands of "how to" videos and articles, plus model-specific schematics and diagrams. We'll take you, step by step, through the entire repair process so you can complete the fix yourself and save some money while doing it.
When appliance parts fail, the symptoms and fixes vary by brand and model. Below are the most important questions customers ask about tiller replacement parts.
Wear from age, heat cycles, and electrical stress are the top causes. Contamination and mechanical strain also shorten yard machines tiller life. Genuine OEM parts installed correctly typically restore full function.
Look for a data plate or label on your unit — typical locations include the door frame, back panel, or inside an access panel. Enter your full model number in our search to pull the exact OEM yard machines tiller for your model.
Most yard machines tiller replacements take between 30 minutes and 2 hours depending on the product type and accessibility. Our step-by-step repair videos walk through disconnection, removal, installation, and testing.


Ordering tiller parts online is simple with our full brand catalog and model-number lookup. With same-day shipping on most in-stock items, you'll have your replacement part fast, minimizing downtime. Our model/part number lookup finds the exact OEM part for your unit, and every order is backed by our 365-day return policy and price-match guarantee. Browse our repair help section for troubleshooting tips, part testing guides, and step-by-step installation videos for your specific product.
Yard Machines typically places the tiller model number on a label attached to the frame, engine housing, or nearby recoil starter. Check these areas carefully, and clean away dirt or oil if the label is hard to read. Record the complete model number, including letters, numbers, and any separators, because similar Yard Machines tillers can use different parts. Type that number into the model number search to pull up the parts matched to your unit. The results cover the complete tiller, so you can narrow the catalog before choosing parts from any category. This approach helps you avoid comparing specifications by hand and gets the repair moving faster.

The online repair library at Repair Clinic covers Yard Machines Tiller diagnostics, part testing, and installation from start to finish. Symptom-based articles narrow the failing component, and matching repair videos or step-by-step written guides walk you through the fix. Use the model number lookup to confirm the exact OEM part before you order, then follow the exploded-view diagrams for a clean reassembly.