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MTD
Rear-Tine Tiller

Model # 21A-450 Official MTD rear tine gas tiller

Here are the diagrams and repair parts for Official MTD 21A-450 rear tine gas tiller, as well as links to manuals and error code tables, if available.

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Owner’s manual

Model diagram and schematic

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Showing 10 of 161 parts  |
Belt-v 1/2x5 754-0434
#20

Outer and inner engine pulley/wheels diagram

Belt-v 1/2x5

Part #754-0434

Replaced by #954-0434

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Manufacturer substitution
This part replaces 754-0434. Substitute parts can look different from the original.
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$45.41 | 
12% OFF Phone Price : $51.41
In Stock
Bearing 741-0124
#43

Gear case assembly diagram

Bearing

Part #741-0124

Replaced by #941-0600

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Manufacturer substitution
This part replaces 741-0124. Substitute parts can look different from the original.
BEST SELLER
$28.71 | 
17% OFF Phone Price : $34.71
In Stock
Tiller Wing Nut 712-0421
#28

Handle/tine adapter/shield diagram

Tiller wing nut

Part #712-0421

Replaced by #712-0421

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Manufacturer substitution
This part replaces 712-0421. Substitute parts can look different from the original.
This item is not returnable
$2.49 | 
29% OFF Phone Price : $3.49
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13" Articula 742-0305
#53

Handle/tine adapter/shield diagram

13" articula

Part #742-0305

Replaced by #742-0305A-0637

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Manufacturer substitution
This part replaces 742-0305. Substitute parts can look different from the original.
$19.50 | 
9% OFF Phone Price : $21.50
In Stock
Air Valve 734-0255
#31

Outer and inner engine pulley/wheels diagram

Air valve

Part #734-0255

Replaced by #934-0255

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Manufacturer substitution
This part replaces 734-0255. Substitute parts can look different from the original.
This item is not returnable
$5.43 | 
16% OFF Phone Price : $6.43
In Stock
Tiller Clutch Cable 746-1117
#18

Outer and inner engine pulley/wheels diagram

Tiller clutch cable

Part #746-1117

Replaced by #946-1117

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Manufacturer substitution
This part replaces 746-1117. Substitute parts can look different from the original.
$73.10 | 
8% OFF Phone Price : $79.10
In Stock
Ryobi Stop Nut 712-0429
#8

Handle/tine adapter/shield diagram

Ryobi stop nut

Part #712-0429

This item is not returnable
$7.06
In Stock
Ryobi Lawn & Garden Equipment Hex Nut (replaces 912-3010) 712-3010
#46

Outer and inner engine pulley/wheels diagram

Ryobi lawn & garden equipment hex nut (replaces 912-3010)

Part #712-3010

$7.71
In Stock
Ryobi Lawn Tractor Screw 710-0376
#11

Gear case assembly diagram

Ryobi lawn tractor screw

Part #710-0376

This item is not returnable
$5.11 | 
16% OFF Phone Price : $6.11
In Stock
Yard Machines Lawn & Garden Equipment Screw 710-1017
Yard machines lawn & garden equipment screw

Part #710-1017

This item is not returnable
$12.71 | 
14% OFF Phone Price : $14.71
In Stock

Most common symptoms to help you fix your tillers

Choose a symptom to see related tiller repairs.

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Why do my tiller's tines turn but the wheels don't?

Main causes: clutch cable problems, faulty transmission…

Read more

Why does my tiller turn the soil poorly?

Main causes: damaged tines, broken clevis pins, worn drive belt, faulty transmission, clutch cable problems, improper de…

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Why won't my tillers wheels or tines turn?

Main causes: worn or broken drive belts, bad transmission, clutch cable problems…

Read more

Why does my tiller's engine leak oil or gas?

Main causes: leaky engine head gasket, damaged sump gasket, damaged oil drain plug seal, loose or cracked fuel line, lea…

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Why do my tiller's wheels turn but the tines don't?

Main causes: broken shaft clevis pins, transmission failure…

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Why does my tiller's engine run roughly or misfire?

Main causes: dirty carburetor, engine needs tune up, stale gas…

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Why won't my tiller's engine start?

Main causes: carburetor failure, bad gasoline, dirty spark plug, broken recoil starter…

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Most common repair guides to help fix your tillers

These step-by-step repair guides will help you safely fix what’s broken on your tiller.

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How to replace a tiller recoil starter

How to replace a tiller recoil starter

The recoil starter spins the engine when you pull the starter rope, and the rope retracts when released. If the recoil s…

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Repair difficulty
Time required
 15 minutes or less

Effective articles & videos to help repair your tillers

Use the advice and tips in these articles and videos to get the most out of your tiller.

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How to enjoy all the online benefits we offer on our Sears PartsDirect website

How to enjoy all the online benefits we offer on our Sears PartsDirect website

Learn about all the convenient features on our Sears PartsDirect website that make your parts purchases easier.…

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Top questions about Sears and Sears PartsDirect

Top questions about Sears and Sears PartsDirect

Get answers to frequently asked questions about Sears and Sears PartsDirect.…

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A guide to garden tillers

A guide to garden tillers

Rear tine tiller or front tine tiller, what to know to help in choosing the correct one for your needs.…

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