Toro Trimmer Parts Diagram
Toro makes gas and electric string trimmers for homeowners. The 51978 is their most popular gas model. This guide covers parts diagrams for Toro trimmer maintenance and repair.
Table of Contents
- Toro Trimmer Models
- Model 51978 Parts
- Trimmer Head Assembly
- Engine Components
- Shaft and Drive Parts
- Common Part Numbers
Toro Trimmer Models
Gas Trimmers
| Model | Engine | Shaft | Features |
|---|---|---|---|
| 51978 | 25.4cc | Straight | Most popular |
| 51998 | 30cc | Straight | More power |
| 51930 | 17cc | Curved | Lightweight |
Electric/Battery Trimmers
| Model | Power | Type |
|---|---|---|
| 51484 | 60V | Battery |
| 51480 | 40V | Battery |
| 51490 | Corded | Electric |
[NEED IMAGE: Toro trimmer model lineup]
Model 51978 Parts
The 51978 is Toro’s bestselling gas trimmer.
Specifications
| Spec | Value |
|---|---|
| Engine | 25.4cc 2-cycle |
| Shaft | Straight |
| Cutting Width | 17 inches |
| Line Size | 0.080” |
| Weight | 12 lbs |
[NEED IMAGE: Toro 51978 parts diagram overview]
Engine Assembly Parts
| Part | Part Number |
|---|---|
| Carburetor | 308480001 |
| Air filter | 308480002 |
| Spark plug | RCJ7Y |
| Fuel filter | 308480003 |
| Primer bulb | 308480004 |
| Ignition coil | 308480005 |
Fuel System
| Part | Part Number |
|---|---|
| Fuel tank | 308480010 |
| Fuel line kit | 308480011 |
| Fuel cap | 308480012 |
| Fuel filter | 308480003 |
Trimmer Head Assembly
Head Components
| Part # | Component | Function |
|---|---|---|
| 1 | Bump knob | Releases line |
| 2 | Spool | Holds line |
| 3 | Spring | Spool tension |
| 4 | Housing | Outer shell |
| 5 | Eyelet | Line exit |
| 6 | Retainer | Holds assembly |
[NEED IMAGE: Toro trimmer head exploded view]
Head Part Numbers
| Part | Part Number |
|---|---|
| Complete head | 308923014 |
| Spool only | 308923015 |
| Bump knob | 308923016 |
| Line 0.080” | 88524 |
Line Replacement
Steps:
- Remove bump knob (turn counterclockwise)
- Remove spool from housing
- Clean debris from housing
- Wind new line onto spool (follow arrows)
- Thread line through eyelets
- Replace spool and bump knob
Line capacity: 20 feet of 0.080” line
Engine Components
Carburetor System
The 51978 uses a diaphragm carburetor typical of 2-cycle engines.
Common issues:
- Won’t start - clogged jets
- Runs rough - needs adjustment
- Dies at idle - air leak or adjustment
- Bogs under load - fuel delivery issue
[NEED IMAGE: Toro 51978 carburetor diagram]
Carburetor Adjustment
Warning: Only adjust if necessary. Factory settings work for most conditions.
Screws:
- H = High speed mixture
- L = Low speed mixture
- T or LA = Idle speed
Basic procedure:
- Start with screws at factory position
- Warm up engine
- Adjust T screw for stable idle
- Adjust L screw for smooth acceleration
- Adjust H screw for max power without 4-stroking
Ignition System
| Part | Part Number |
|---|---|
| Ignition coil | 308480005 |
| Spark plug | RCJ7Y |
| Flywheel | 308480020 |
| Kill switch | 308480021 |
Spark plug gap: 0.025 inches
Shaft and Drive Parts
Shaft Assembly
| Part | Part Number |
|---|---|
| Shaft tube | 308480030 |
| Drive shaft | 308480031 |
| Shaft bearing | 308480032 |
| Grip handle | 308480033 |
| Throttle cable | 308480034 |
Gearbox (Lower)
| Part | Part Number |
|---|---|
| Gearbox housing | 308480040 |
| Gearbox gears | 308480041 |
| Gearbox grease | 308480042 |
Gearbox maintenance:
- Add grease every 25 hours
- Use trimmer gearbox grease only
- Fill through grease fitting
[NEED IMAGE: Toro trimmer gearbox parts]
Common Part Numbers
Maintenance Items
| Part | Part Number | Interval |
|---|---|---|
| Air filter | 308480002 | 25 hours |
| Spark plug | RCJ7Y | 50 hours |
| Fuel filter | 308480003 | 50 hours |
| Trimmer line | 88524 | As needed |
| Gearbox grease | 308480042 | 25 hours |
Wear Items
| Part | Part Number |
|---|---|
| Trimmer head | 308923014 |
| Primer bulb | 308480004 |
| Fuel lines | 308480011 |
| Throttle cable | 308480034 |
Troubleshooting
Won’t Start
- Check fuel freshness (mix 50:1)
- Prime 5-7 times
- Check spark plug
- Verify kill switch off
- Clean air filter
- Check carburetor
Runs Rough
- Clean air filter
- Replace spark plug
- Check fuel mix ratio
- Adjust carburetor
- Check for air leaks
Line Won’t Feed
- Check line length (not too short)
- Verify line not fused together
- Clean head housing
- Check bump mechanism
- Replace head if damaged
Related Guides
- String Trimmer Won’t Start
- How to Clean a 2-Cycle Carburetor
- Toro Lawn Mower Manual Guide
- Echo Trimmer Problems
Summary
Toro trimmers share many parts across the product line. The 51978 is the most common model with readily available parts. Regular maintenance includes air filter cleaning, spark plug replacement and gearbox greasing. Trimmer head and line are the most frequently replaced items.