Toro Carburetor Linkage Diagram

Carburetor linkage on Toro mowers controls throttle, choke and engine speed. Getting it wrong causes surging, stalling or over-revving. This guide shows how the linkage connects on common Toro Recycler engines.

Table of Contents

• Linkage System Overview
• Briggs & Stratton Linkage
• Kohler Engine Linkage
• Governor System Basics
• Choke Linkage Setup
• Common Linkage Problems
• Linkage Adjustment Procedures

Linkage System Overview

Toro Recycler mowers use three interconnected linkage systems.

The Three Systems

1. Throttle Linkage

• Controls throttle plate position
• Determines air/fuel mixture rate
• Connected to governor for speed control

2. Governor Linkage

• Maintains constant engine speed under load
• Spring tension sets target RPM
• Governor arm responds to engine speed changes

3. Choke Linkage

• Controls choke plate for cold starting
• Auto-choke uses engine heat
• Manual choke uses cable or lever

[NEED IMAGE: Toro carburetor linkage system overview]

Why Linkage Matters

Correct linkage setup ensures:

• Stable engine speed (no surging)
• Proper response to load changes
• Correct cold starting behavior
• Safe maximum RPM limits

Briggs & Stratton Linkage

Most Toro Recyclers use Briggs engines. Linkage varies by engine series.

650-750 Series (140-163cc)

These engines use a simple linkage with plastic governor arm.

Components:

1. Governor arm (plastic, on governor shaft)
2. Governor spring (connects arm to throttle)
3. Throttle lever (on carburetor)
4. Governor link (solid rod)

[NEED IMAGE: Briggs 650-750 series governor linkage diagram]

Spring placement:

• Governor arm has two holes
• Inner hole = higher RPM
• Outer hole = lower RPM
• Standard is outer hole for lawn mowers

Linkage routing:

1. Governor link connects governor arm to carburetor throttle
2. Governor spring connects arm to engine bracket
3. Spring tension pulls throttle open
4. Governor arm closes throttle when engine speeds up

850-875 Series (190cc)

The larger engines have similar but beefier linkage.

Key differences from 650/750:

• Heavier governor spring
• Metal governor arm on some models
• Additional link for auto-choke

[NEED IMAGE: Briggs 850-875 series linkage diagram]

ReadyStart System

Newer Briggs engines with ReadyStart have automatic choke.

Auto-choke components:

• Thermostatic spring (heat sensitive)
• Choke link (connects spring to choke plate)
• No manual choke or primer

How it works:

1. Cold engine - spring holds choke closed
2. Engine warms up - spring relaxes
3. Choke opens automatically
4. Fully warm - choke stays open

[NEED IMAGE: Briggs ReadyStart auto-choke linkage]

Kohler Engine Linkage

Some Toro Recyclers use Kohler engines with different linkage.

Kohler SH Series

The Kohler SH265 and SH265 use a governor system similar to Briggs but with Kohler-specific parts.

Components:

1. Governor gear (internal)
2. Governor arm (external)
3. Governor spring
4. Throttle link
5. Choke lever

[NEED IMAGE: Kohler SH series governor linkage]

Key difference: Kohler uses a direct linkage from governor arm to throttle. No intermediate link on most models.

Kohler Choke System

Kohler engines typically use manual choke controlled by a lever.

Choke operation:

• Lever in CHOKE position closes plate
• Lever in RUN position opens plate
• No automatic choke on most models

Governor System Basics

Understanding the governor helps troubleshoot surging and speed problems.

How Governors Work

The governor maintains constant speed regardless of load.

Mechanical governor operation:

1. Flyweights spin with engine
2. Higher speed = weights swing out
3. Weights push governor arm
4. Arm closes throttle slightly
5. Lower speed = weights retract
6. Spring opens throttle

This constant balancing keeps speed steady.

[NEED IMAGE: Mechanical governor operation diagram]

Governor Spring Tension

The spring determines the target RPM.

Spring effects:

• Stronger spring = higher RPM
• Weaker spring = lower RPM
• Wrong spring = wrong speed or surging

Common mistake: Installing wrong length or tension spring causes chronic surging.

Static Governor Adjustment

Set the governor arm position with engine off.

Procedure:

1. Loosen governor arm clamp bolt
2. Move throttle to wide open position
3. Rotate governor shaft clockwise (looking from above)
4. Hold shaft while tightening clamp bolt
5. This pre-loads the governor in the right direction

Choke Linkage Setup

Choke linkage must allow full open and full closed positions.

Manual Choke Linkage

Components:

• Choke cable or lever
• Choke link rod
• Choke plate on carburetor
• Return spring (some models)

Setup check:

1. Move choke lever to CHOKE
2. Choke plate should be fully closed
3. Move lever to RUN
4. Plate should be fully open
5. Adjust link length if needed

[NEED IMAGE: Toro manual choke linkage setup]

Auto-Choke Linkage

Components:

• Thermostatic spring (on intake)
• Choke link
• Choke plate

Verification:

1. Cold engine - choke should be closed
2. After 2-3 minutes running - choke opens
3. Hot engine - choke stays fully open

Problem signs:

• Hard cold starting = choke not closing
• Black smoke/rough idle = choke not opening

Common Linkage Problems

Linkage issues cause specific symptoms.

Engine Surging

Causes:

• Governor spring in wrong hole
• Stretched governor spring
• Air leak at carburetor mount
• Governor arm loose on shaft
• Dirty carburetor affecting governor response

Fix order:

1. Check spring position
2. Verify arm tight on shaft
3. Check for air leaks
4. Clean carburetor if needed

Engine Over-Revs

Causes:

• Governor spring too strong
• Governor link disconnected
• Governor arm slipped on shaft
• Internal governor failure

Warning: Over-revving damages engines. Don’t run if speed is uncontrolled.

Fix:

1. Reconnect any disconnected linkage
2. Reset static governor adjustment
3. Replace governor if internal failure

Engine Won’t Reach Full Speed

Causes:

• Governor spring too weak
• Throttle linkage binding
• Governor arm bent
• Carburetor throttle not opening fully

Fix:

1. Check throttle plate opens fully
2. Verify spring tension correct
3. Straighten or replace bent parts
4. Adjust governor static setting

Choke Stuck Closed

Causes (auto-choke):

• Thermostatic spring broken
• Choke link bent or stuck
• Carbon buildup on choke plate

Fix:

1. Check spring operation
2. Straighten link if bent
3. Clean choke plate and shaft

Choke Won’t Close

Causes:

• Cable stretched (manual)
• Thermostatic spring weak (auto)
• Linkage disconnected

Fix:

1. Adjust or replace cable
2. Replace thermostatic spring
3. Reconnect linkage

Linkage Adjustment Procedures

Step-by-step adjustments for common issues.

Governor Static Adjustment

Perform after any governor work.

Tools: 10mm wrench, screwdriver

Steps:

1. Remove air filter for access
2. Locate governor arm clamp bolt
3. Loosen clamp bolt (don’t remove)
4. Move throttle lever to wide open
5. Hold throttle open
6. Rotate governor shaft fully clockwise
7. Tighten clamp bolt while holding shaft
8. Release throttle
9. Reinstall air filter
10. Start and verify speed stability

[NEED IMAGE: Toro governor static adjustment procedure]

Throttle Cable Adjustment

For mowers with throttle cable controls.

Steps:

1. Locate cable adjuster barrel
2. Loosen jam nut
3. Turn barrel to adjust
4. Verify full throttle reaches wide open
5. Verify idle position is correct
6. Tighten jam nut

Choke Cable Adjustment

For manual choke systems.

Steps:

1. Move choke lever to RUN
2. Check that choke plate is fully open
3. If not, adjust cable at clamp
4. Move lever to CHOKE
5. Plate should be fully closed
6. Readjust if needed

Parts Reference

Common linkage parts for Toro Recyclers.

Briggs Governor Parts

Part	Part Number	Notes
Governor spring	691859	Standard tension
Governor arm	691841	Plastic arm
Governor link	691821	Throttle to arm
Governor shaft	Inside engine	Not serviceable
Clamp bolt	93029	Arm to shaft

Choke Parts

Part	Part Number	Notes
Auto-choke spring	691279	Thermostatic
Choke link	691306	Rod
Choke shaft	In carburetor	Replace with carb

Throttle Parts

Part	Part Number	Notes
Throttle lever	In carburetor	Replace with carb
Throttle spring	691777	Return spring
Throttle cable	Model specific	Check parts catalog

Related Guides

• Toro Carburetor Repair
• How to Clean a Carburetor
• Briggs & Stratton 799866 Carburetor
• Lawn Mower Surging Fix

Summary

Toro carburetor linkage follows standard small engine patterns. The governor spring connects the governor arm to the throttle lever. The choke linkage controls the choke plate based on engine temperature. Most surging problems trace to wrong spring position or loose governor arm.

Always photograph linkage before disconnecting anything. Reset the static governor adjustment after any carburetor or linkage work. Use correct replacement springs - wrong tension causes chronic problems.