Service Manual

Engine Specifications
Bore 2.3810 2.3800 (60.477 85.852 mm)
Stroke 1.7520 1.7497” (44.501 44.442 mm)
Connecting rod length 3.00 (76.2 mm)
Wrist pin diameter
.5000” (12.7 mm)
Wrist pin offset
.070 (1.78 mm) toward major thrust side
Crankpin diameter
.742” (18.85 mm)
Top and bottom main bearings Dia: Top: .875” (22.23 mm) Bottom:1.125” (28.58 mm)
Displacement
7.78 cu in (127.51 cc)
Horsepower
4.5
Compression ratio 5.91:l (Range of 5.151 6.668:l)
Carburetor ‘93 models
Carburetor ‘94 models up)
Fuel required
Recommended oil
Fuel tank capacity
Ignition type
CD Pack air gap
Spark timing
Dual circuit Walbro, float type,’ with fixed main jet
Single-circuit Lawn-Boy with fixed main jet, float type, with primer
32:l premix unleaded regular (87 octane 2-cycle oil
Lawn-Boy Ashless 2-cycle oil
1.5 quarts
Solid state CD Pack, magneto type
.010 (.25 mm)
2’ 8’ BTDC (Cranking); 22’ 28’ (Running)
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Spark plug air gap Champion RJ12C .035 (.889 mm)
Starting system
Governor Air vane
Rope rewind
Governed engine speed
Idle speed
3050+/- 100 RPM
2200 2800 RPM
Air cleaner
Choke
Fuel filter
Oiled, foam type
Manual, butterfly type (Walbro only)
ln-tank and in-carburetor
Piston Permanent mold, high silicon aluminum
Piston rings Cast iron, semi-keystone top ring
10
Reference Section