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Tecumseh HS40 Engine

General Technical Data

Tecumseh HS40 Engine Specifications

Engine Model ........... Tecumseh HS40
Engine Type ........... 4-cycle L-head single-cylinder horizontal small frame air-cooled gasoline engine
Number of Cylinders ........... 1
Displacement, cu.in (cc) ........... 10.49 (171.93)
Cylinder Bore, in (mm) ........... 2.63 (66.7)
Piston Stroke, in (mm) ........... 1.94 (49.2)
Rated Engine Power, hp (kW) ........... 4.0 (2.96)
Rated Engine Speed, rpm ........... 3600
Maximum Torque, Nm (ft-lbs) ........... 8.9 (6.6)
Torque Speed, rpm ........... 2600
Compression Ratio ........... 8.13:1
Lubrication System ........... Splash type
Air Cleaner ........... Paper element
Cooling System ........... Forced air
Ignition System ........... Magneto with dust and moisture seal
Starting System ........... Recoil or electric starter
Crankshaft ........... Iron alloy
Bearings (PTO End/Flywheel End) ........... Aluminum alloy
Cylinder ........... Diecast aluminum alloy
Intake Valves ........... Heat treated iron alloy
Exhaust Valves ........... Austenitic steel
Electrical System Rating, Volts ........... 12

Fuel System

Fuel System Type ........... Carburetor
Carburetor Type ........... Float, adjustable jet
Governor Type ........... Mechanical, running in crankcase oil
Fuel Tank Capacity, qts (L) ........... 2.0 (1.9)
Fuel Filter ........... Fine mesh molded into tank

Dimensions and Weight

Overall Length, in (mm) ........... 16.9 (428)
Overall Width, in (mm) ........... 9.4 (238)
Overall Height, in (mm) ........... 13.2 (334)
Net Weight, lbs (kg) ........... 27.0 (12.3)

Tecumseh HS40 Maintenance Data

Cylinder Block and Valves

Cylinder Bore Inside Diameter (Maximum), in (mm) ........... 2.6260 (66.700)
Cylinder Head (Max. Out of Flatness), in (mm) ........... 0.005 (0.127)
Intake Valve Clearance, in (mm) ........... 0.004-0.008 (0.102-0.203)
Exhaust Valve Clearance, in (mm) ........... 0.004-0.008 (0.102-0.203)

Engine Oil and Filter

Engine Oil Type (Summer) ........... SAE 30, 10W-30
Engine Oil Type (Winter) ........... SAE 5W-30
API Service Classifications ........... SF or SJ
Oil Capacity, qts (L) ........... 0.67 (0.63)
Air Filter Element Part Number ........... 30727/31700

Carburetor Adjustments

Main Pre-Set ........... 1-1/2 turn
Idle Pre-Set ........... 1 turn
Low Idle Speed, rpm ........... 1600-1800
High Idle Speed, rpm ........... 3600-3900

Ignition System

Spark Plug Type ........... Champion RJ17LM
Spark Plug Gap, in (mm) ........... 0.030 (0.762)
Breaker Point Gap, in (mm) ........... 0.020 (0.508)
Timing Dim. BTDC, in (mm) ........... 0.035 (0.889)
Spark Plug Torque, Nm (ft-lbs) ........... 21 (28.5)

Service Intervals

Service Air Cleaner Element ........... Every 25 hrs
Change Engine Oil ........... Every 25 hrs
Clean Cooling Fins ........... Every 25 hrs
Check and Adjust Spark Plug ........... Every 100 hrs
Replace Air Cleaner Element ........... Every 100 hrs
Check Carburetor Adjustment ........... Every 100 hrs
Check and Adjust Valve Clearance ........... Every 200 hrs
Replace Spark Plug ........... Every 200 hrs

Tecumseh HS40 Service Specifications

Cylinder Bore (Standard), in (mm) ........... 2.6250 (66.675)
Cylinder Bore (Maximum), in (mm) ........... 2.6260 (66.700)
Cylinder Main Bearing, in (mm) ........... 1.0005-1.0010 (25.413-25.425)
Cylinder Cover/Flange Main Bearing Diameter, in (mm) ........... 1.0005-1.0010 (25.413-25.425)
Valve Clearance, in (mm) ........... 0.004-0.008 (0.102-0.203)
Valve Seat Width, in (mm) ........... 0.035-0.045 (0.889-1.143)
Valve Guide Oversize Dimensions, in (mm) ........... 0.2807-0.2817 (7.130-7.155)
Valve Seat Angle, deg ........... 46
Crankshaft End Play, in (mm) ........... 0.005-0.027 (0.127-0.686)
Crankpin Journal Diameter, in (mm) ........... 0.9995-1.0000 (25.387-25.400)
Crankshaft Magneto Main Bearing Diameter, in (mm) ........... 0.9985-0.9990 (25.362-25.375)
Crankshaft PTO Main Bearing Diameter, in (mm) ........... 0.9985-0.9990 (25.362-25.375)
Camshaft Bearing, in (mm) ........... 0.4975-0.4980 (12.637-12.649)
Connecting Rod Diameter (Crank Bearing), in (mm) ........... 1.0005-1.0010 (25.413-25.425)
Piston Diameter Bottom Of Skirt, in (mm) ........... 2.6202-2.6210 (66.553-66.573)
Ring Groove Side Clearance (Compession Rings), in (mm) ........... 0.002-0.005 (0.051-0.127)
Ring Groove Side Clearance (Oil Ring), in (mm) ........... 0.001-0.004 (0.025-0.102)
Piston Skirt Clearance, in (mm) ........... 0.0040-0.0058 (0.102-0.147)
Ring End Gap, in (mm) ........... 0.007-0.017 (0.178-0.432)

Tecumseh HS40 Torque Specifications

Cylinder Head Bolts, ft-lbs (Nm) ........... 16.5 (22.5)
Connecting Rod Bolts, ft-lbs (Nm) ........... 8.5 (11.5)
Cylinder Cover or Flange, ft-lbs (Nm) ........... 9.5 (13)
Flywheel Nut (Aluminum), ft-lbs (Nm) ........... 37.5 (51)
Spark Plug, ft-lbs (Nm) ........... 21 (28.5)
Ignition Mounting (Stud to Cylinder), ft-lbs (Nm) ........... 3 (4.1)
Ignition Mounting (to Stud), ft-lbs (Nm) ........... 4 (5.5)
Intake Pipe to Cylinder, ft-lbs (Nm) ........... 8 (11)
Carburetor to Intake Pipe, ft-lbs (Nm) ........... 6 (8)
Muffler Mounting No Shoulder Screw, ft-lbs (Nm) ........... 2 (2.7)
Muffler Mounting (Pancake), ft-lbs (Nm) ........... 3 (4.1)
Muffler Mtg. Flanged, ft-lbs (Nm) ........... 6.5 (9)
Magneto Stator To Cylinder, ft-lbs (Nm) ........... 5.5 (7.5)
Recoil Starter (Top Mount), ft-lbs (Nm) ........... 4 (5.5)
Electric Starter To Cylinder, ft-lbs (Nm) ........... 5.5 (7.5)