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Honda V-Twin Horizontal OHV Engine with Electric Start – 688cc, GX Series, 1 1/8in. x 3.55in. Shaft, Model# GX660RHTDW

Item# 166139
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Honda V-Twin Horizontal OHV Engine with Electric Start – 688cc, GX Series, 1 1/8in. x 3.55in. Shaft, Model# GX660RHTDW

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  • 688cc air-cooled, 4-stroke OHV engine
  • 50-state compliant engine
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Product Summary

With experience born on the raceways and roadways and a dedication to innovation, there's plenty of reasons to insist on the new Honda GX660 V-Twin engine. There's superior engine design, with a 90° configuration that reduces vibration and allows a compact footprint. There's superior construction, with a forged steel crankshaft and an integrated cylinder head. Fewer parts means better durability. There's a digital CDI ignition coil that ensures improved fuel economy and lowered emissions. There's even improved air cleaning, meaning that you can wait 5 times longer between filter changes. Honda even gives their engines a 3-year limited warranty.

The image shown is not reflective of the actual item shipped. There is no control panel as shown in the image.

What's Included
  • (1) Engine, Model# GX660RTDW
pdf Product Manual
pdf Dimensions and Performance Curve

Features + Benefits

  • 688cc air-cooled, 4-stroke OHV engine
  • 50-state compliant engine
Key Specs
Item# 166139
Brand Honda Engines
Manufacturer's Warranty 3 year limited warranty
Ship Weight 110.0 lbs
Engine Displacement (cc) 688
Start Type Electric, shift type
Application Lawn tractor, mower, utility vehicle, concrete saw, pressure washer, chipper/shredder, trencher, vibratory roller, ride-on cement trowel
Engine Type GX series OHV V-Twin commercial-duty
Net Power Output (HP) 21.5 (16.0 kW) at 3,600 RPM
Net Torque (lbs./ft.) 35.6 (48.3 Nm) at 2,500 RPM
Shaft Output Horizontal
Crankshaft T type
Shaft Diameter (in.) 1 1/8
Shaft Length (in.) 3.55
Shaft Keyway (in.) 1/4, (Key size 6.3mm x 70mm)
Shaft End Tapped (Diameter (in.)/Threads per inch) 7/16–20, UNF2B
Shaft Rotation (From PTO Shaft Side) Counterclockwise
PTO Height (in.) 5 1/4
Cylinders (qty.) 2
Cylinder Bore Integrated
Bore x Stroke (in.) 3.1 x 2.8
Compression Ratio 9.3:1
Cooling System Air cooled
Air Cleaner Type Dual element/cylindrical
Fuel Tank Not included
Fuel Type Gasoline
Fuel Pump Boost type
Oil Capacity (qt.) 2
Lubrication System Full pressure
Ignition System Electonic, digital CDI w/variable ignition timing
Governor System Mechanical
Carburetor 2-barrel, fuel cut solenoid, inner vent
Throttle Control Remote (wire)
Choke Control Remote (wire)
Max. RPM 3,600
Charging System Amps 20
Muffler Included Not included
Flywheel Brake No
Bolt Circle (in.) 5, 6 1/2, 7 3/4
Mounting Base L x W (in.) 7 11/16 x 3 25/64–4 21/32
Dimensions L x W x H (in.) 15 7/8 x 16 1/8 x 17 3/16
EPA/CARB Approval (California Air Resource Board) Yes

Customer Reviews

Product Question + Answer
Accessories Frequently Purchased with this Item

You'll Need

Mufflers
High-Mount Muffler for Honda V-Twin Engines — Fits GX630, 660 and 690 Engines, Right/Oil Filter Side Mount, Model# MUF-0560.SIL		 High-Mount Muffler for Honda V-Twin Engines — Fits GX630, 660 and 690 Engines, Right/Oil Filter Side Mount, Model# MUF-0560.SIL
Item# 601099
 Factory Shipped —
Estimated Delivery: 5 - 7 Business Days
Only $139.99
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High-Mount Muffler for Honda V-Twin Engines — Fits GX630, 660 and 690 Engines, Left/Starter Side Mount, Model# MUF-0560R.SIL		 High-Mount Muffler for Honda V-Twin Engines — Fits GX630, 660 and 690 Engines, Left/Starter Side Mount, Model# MUF-0560R.SIL
Item# 601105
 Factory Shipped —
Estimated Delivery: 5 - 7 Business Days
Only $139.99
 Add to Cart
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Misc. Accessories
Drainzit Oil Drain Hose — 14mm Port, Model# HON1014-C.DRA		 Drainzit Oil Drain Hose — 14mm Port, Model# HON1014-C.DRA
Item# 7011543
 In Stock Online
Only $19.99
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Oil Filters
Honda OEM Oil Filter — Model# 15400-PLM-A01PE		 Honda OEM Oil Filter — Model# 15400-PLM-A01PE
Item# 7011550000
 In Stock Online
Only $8.99
 Add to Cart
Safety
Eye Protection
3M Metaliks Sport Safety Glasses — Indoor/Outdoor Tinted Lens, Model# 11345-00000		 3M Metaliks Sport Safety Glasses — Indoor/Outdoor Tinted Lens, Model# 11345-00000
Item# 174694
 In Stock Online
Only $9.99
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Replacement Parts
Call To Order: 1-800-657-0516

Mon - Fri 7:00 AM - 6:00 PM (Central)
Sat 7:00 AM - 3:00 PM (Central)

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Honda V-Twin Horizontal OHV Engine with Electric Start – 688cc, GX Series, 1 1/8in. x 3.55in. Shaft, Model# GX660RHTDW The price is $1,299.99.
Honda V-Twin Horizontal OHV Engine with Electric Start – 688cc, GX Series, 1 1/8in. x 3.55in. Shaft, Model# GX660RHTDW
5 / 5 (1)
Item# 166139
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Engine Displacement (cc)
 688 688 688 688 688
Start Type
 Electric start Electric, shift type Electric, shift type Electric Electric
Application Concrete saw, pressure washer, chipper/shredder, trencher, vibratory roller, ride-on cement trowel Lawn tractor, mower, utility vehicle, concrete saw, pressure washer, chipper/shredder, trencher, vibratory roller, ride-on cement trowel Grain auger/elevator, pressure washer, semi-trailer w/power pack Pressure washer, lawn/garden equipment, generator, small vehicle, water pump Grain auger/elevator, pressure washer, semi-trailer w/power pack
Engine Type GX series OHV V-Twin commercial-duty GX series OHV V-Twin commercial-duty GX series OHV V-Twin commercial-duty GX series OHV V-Twin GX series OHV V-Twin
Net Power Output (HP) 20.8 (15.5 kW) at 3,600 RPM 21.5 (16.0 kW) at 3,600 RPM 21.5 (16.0 kW) at 3,600 RPM 22.1 (16.5 kW) at 3,600 RPM 22.1 (16.5 kW) at 3,600 RPM
Net Torque (lbs./ft.) 35.6 (48.3 Nm) at 2,500 RPM 35.6 (48.3 Nm) at 2,500 RPM 35.6 (48.3 Nm) at 2,500 RPM 35.6 (48.3 Nm) at 2,500 RPM 35.6 (48.3 Nm) at 2,500 RPM
Shaft Output
 Horizontal Horizontal Horizontal Horizontal Horizontal
Crankshaft Q-type T type T type T type T type
Shaft Diameter (in.) 1 1 1/8 1 1/8 1 1/8 1 1/8
Shaft Length (in.) 2 29/32 3.55 3 31/32 2 29/32 3.55
Shaft Keyway (in.)
 1/4, (Key size 6.3mm x 50mm) 1/4, (Key size 6.3mm x 70mm) 1/4, (Key size 6.3mm x 70mm) 1/4 (key size 6.3mm x 70mm) 1/4 (key size 6.3mm x 70mm)
Shaft End Tapped (Diameter (in.)/Threads per inch) 3/8–24, UNF2B 7/16–20, UNF2B 7/16–20, UNF2B 7/16–20, UNF2B 7/16–20, UNF2B
Shaft Rotation (From PTO Shaft Side) Counterclockwise Counterclockwise Counterclockwise Counterclockwise Counterclockwise
PTO Height (in.) 5 1/4 5 1/4 5 1/4 5 1/4 -
Bearing Type
 - - - Ball bearing Ball bearing
Cylinders (qty.)
 2 2 2 2 2
Cylinder Bore
 Integrated Integrated Integrated Integrated Integrated
Bore x Stroke (in.)
 3.1 x 2.8 3.1 x 2.8 3.1 x 2.8 78 x 72 3.1 x 2.8
Compression Ratio
 9.3:1 9.3:1 9.3:1 9.3:1 9.3:1
Cooling System
 Air cooled Air cooled Air cooled Air cooled Air cooled
Air Cleaner Type
 Dual element/cylindrical Dual element/cylindrical Dual element/cylindrical Dual element Dual element
Fuel Tank Not included Not included Not included No No
Fuel Type Gasoline Gasoline Gasoline Gas Gas
Fuel Pump
 Boost type Boost type Boost type Boost type Boost type
Fuel Filter - - - Fuel strainer -
Oil Capacity (qt.)
 2 2 2 2.1 2
Lubrication System
 Full pressure Full pressure Full pressure Forced lubrication Full pressure
Low Oil Alert
 Yes - Yes No Yes
Low Oil Shutdown
 - - - No No
Ignition System
 Electonic, digital CDI w/variable ignition timing Electonic, digital CDI w/variable ignition timing Electonic, digital CDI w/variable ignition timing Electrical, digital CDI w/variable ignition timing Electrical, digital CDI w/variable ignition timing
Governor System
 Mechanical Mechanical Mechanical Mechanical Mechanical
Carburetor
 2-barrel, fuel cut solenoid, inner vent 2-barrel, fuel cut solenoid, inner vent 2-barrel, fuel cut solenoid, inner vent Horizontal, two-barrel butterfly valve, internal vent (2) Barrel, fuel cut solenoid, inner vent
Throttle Control
 Manual Remote (wire) Manual Remote Manual
Choke Control
 Manual Remote (wire) Manual Remote Manual
Max. RPM
 3,600 3,600 3,600 3,600 3,600
Charging System Amps 2.7 20 20 20 20
Muffler Included
 Not included Not included Not included No No
Flywheel Brake
 No No No No No
Auto Compression Release - - - Yes -
Bolt Circle (in.)
 5, 6 1/2, 7 3/4 5, 6 1/2, 7 3/4 5, 6 1/2, 7 3/4 5, 6 1/2, 7 3/4 5, 6 1/2, 7 3/4
Mounting Base L x W (in.)
 7 11/16 x 3 25/64–4 21/32 7 11/16 x 3 25/64–4 21/32 7 11/16 x 3 25/64–4 21/32 7 11/16 x 3 25/64–4 21/32 7 11/16 x 3 25/64–4 21/32
Dimensions L x W x H (in.)
 15 7/8 x 16 1/8 x 17 3/16 15 7/8 x 16 1/8 x 17 3/16 15 7/8 x 16 1/8 x 17 3/16 15 9/10 x 16 1/10 x 17 1/5 16 x 18 x 18
EPA/CARB Approval (California Air Resource Board)
 Yes Yes Yes Yes Yes

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