The Honda GX670 is a 670 cc (40.9 cu-in) V-twin cylinder air-cooled four-stroke internal combustion small gasoline engine with horizontal shaft manufactured by Honda Motor Company for general-purpose applications, such as concrete saws, pressure washers, chipper and shredders, trenchers, generators, vibratory rollers, ride-on cement trowels, lawn tractors.
The Honda GX670 engine has an OHV (overhead valve) design with 90° V-twin cylinders; horizontal type carburetor with butterfly valve; electric starter and transistorized magneto ignition system.
The 90° V-twin OHV format featuring an advanced combustion chamber design and superior intake and exhaust efficiency combines the ordinarily opposed elements of good fuel economy and high power output at the highest possible levels. An advanced breather design and three-piece oil ring improve oil circulation efficiency for lower oil consumption. The result is excellent reliability plus reduced running and maintenance costs.
The cylinder bore is 77.0 mm (3.0 in) and the piston stroke is 72.0 mm (2.8 in), the compression ratio rating is 8.3:1. The GX670 engine produced 24 HP (17.7 kW HP) of horsepower at 3,600 rpm and 50.8 N·m (5.18 kg·m, 37.5 ft·lb) of torque at 2,500 rpm.
General information
| Engine Specifications | |
| Model | GX670 |
| Type | 4-stroke, OHV, 90° V-twin |
| Displacement | 670 cm 3 (40.9 cu-in) |
| Max. horsepower | 24 HP (17.7 kW HP) at 3,600 rpm |
| Max. torque (crank PTO) | 50.8 N·m (5.18 kg·m, 37.5 ft·lb) at 2,500 rpm |
| Carburetor | Horizontal type, butterfly valve |
| Cooling system | Forced-air |
| Ignition system | Transistorized magneto ignition |
| Lubricating system | Forced lubrication |
| Starting system | Electric starter |
| Stoping system | Ignition primary circuit ground |
| Fuel used | Unleaded gasoline (octane number 86 or higher) |
| Fuel consumption | 265 g/HPh |
| PTO shaft rotation | Counterclockwise (from PTO shaft side) |
Cylinder Block and Head
Improved crankcase rigidity, extra-durable crankshaft, and optimized cam shape reduce mechanical noise and contribute to quieter, smoother continuous operation. The Honda GX670 U/R motor equipped with high-strength sintered aluminum connecting rods to reduce weight in overlap areas and minimize vibration caused by the cylinder offset.
| Cylinder block | ||
| Compression ratio: | 8.3:1 | |
| Bore x Stroke | 77 X 72 mm (3.0 x 2.8 in) | |
| Sleeve internal diameter | 77.00 mm (3.03 in) | |
| Piston skirt outer diameter | 76.985 mm (3.03 in) | |
| Cylinder Head | ||
| Warpage (limit) | 0.10 mm (0.004 in) | |
| Valve Arrangement: | OHV | |
| Valves: | 4 (2 per cylinder) | |
Tightening torque specs
| Tightening torque specs | |
| Connecting rod bolt | 12 Nm; 1.2 kg·m; 9 ft·lb |
| Cylinder head bolt | 34 Nm; 3.5 kg·m; 25 ft·lb |
| Socket bolt | 27 Nm; 2.7 kg·m; 20 ft·lb |
| Flywheel nut | 196 Nm; 20.0 kg·m; 145 ft·lb |
| Pivot bolt | 24 Nm; 2.4 kg·m; 17 ft·lb |
| Pivot adjusting nut | 10 Nm; 1.0 kg·m; 7 ft·lb |
| Cylinder head cover bolt | 9 Nm; 0.9 kg·m; 6.5 ft·lb |
| Oil level switch joint nut | 10 Nm; 1.0 kg·m; 7 ft·lb |
| Oil drain bolt | 39 Nm; 4.0 kg·m; 29 ft·lb |
| Standard torque values | |
| Bolt, nut (5 mm) | 5.5 Nm; 0.55 kg·m; 4.0 ft·lb |
| Bolt, nut (6 mm) | 10 Nm; 1.0 kg·m; 7 ft·lb |
| Bolt, nut (8 mm) | 22 Nm; 2.2 kg·m; 16 ft·lb |
| Bolt, nut (10 mm) | 34 Nm; 3.5 kg·m; 25 ft·lb |
| Bolt, nut (12 mm) | 54 Nm; 5.5 kg·m; 40 ft·lb |
Service Information
| Engine | |
| Maximum speed | 3,850 ± 100 rpm |
| Idle speed | 1,400 ± 150 rpm |
| Cylinder compression | 6.0-8.0 kg/cm2 (85-114 psi) at 500 rpm |
| Valve clearance | |
| Intake valve clearance | 0.15±0.02 mm (0.006±0.001 in) |
| Exhaust valve clearance | 0.20±0.02 mm (0.008±0.001 in) |
| Oil system | |
| Oil type | Honda 4-stroke or an equivalent (SG or SF) |
| Recommended oil | SAE 10W-30 |
| Oil capacity | 1.90 L |
| Oil change interval | Every 6 month or 100 Hrs. |
| Ignition system | |
| Spark plug | NGK: ZGR5A DENSO: J16CR-U |
| Spark plug gap | 0.7-0.8 mm (0.028-0.031 in) |
Author:
i need a new engine price
Hello, we are not a supplier of engines, we are only an information portal with technical specifications, so we have no any price lists.
The Honda GX690 (22.1 hp) is about $1500, or so, but the exhaust is optional at about another $150. A Predator from Harbor Freight is a Honda clone and rated at 22 hp. Most parts will interchange. The Predator, presently, retails for $749. It’s a much better buy.
I personally dont think the predator is that great considering the fact that it is chinese and will only last a couple hundred hours or miles depending on use. Performance670 makes some great parts for them though.
$1000
I have a honda 670 that will start but dies within 10 seconds. Any idea why? Sensor?
Old fuel or blockage in the main jet. Give the carb a good cleaning and replace the fuel.
Where did you buy the Honda GX670 24hp engine?
Bought mine years ago at Northern Tools in Richmond, VA. The GX 690 took it’s place.
funny enough the iGX690 makes only 0.9hp and 2.7 ft-lbs more than the gx670
Run it with the choke out as long as it will run. and then crank it( it will be flooded) but it may fix things..mine did.
Oil Pressure Sensor is bad or oil is Low (or needs an oil change!)
they have a fuel cut off solenoid that screws into the bottom of the carby ‘ if they don’t open as they should no/little fuel .this could be your problem
Clean your carburetor
Fuel solenoid
I have a gx670 v twin motor front coil fires good back one not at all bought a new coil still wont fire is there a difference in the front and back coil
They have the same Part Number: 30550-ZJ1-845
I’m trying to mount a mag pickup off the fly wheel. Is there another way to get a rpm reading for a external computer?
ineed 1in shaft adpter for fly wheel installing on 737jd mower removing kswasaki
Hej , jeg har en Honda Gx 670 generator, den går op og ned i omdrejninger, den starter fint, men vil ikke gå op og yde max, hvad kan det skyldes, mvh Lars Friis
I just bought a duck boat with a gx670 with electric srart motor. The manual shows a fuel pump attached to the motor. But it has a external inline fuel pump. Dose this mean the original fuel pump is not working?
Hi, I bought this gx670 engine to replace the kawasaki kx600v for my stand up mower. Will this fit?
If you have an electric fuel pump … you should be able to hear it pumping when you turn it on.
Anyone know the shaft diameter on the GX670? Thanks!
1-1/8″
A Predator 22 hp is the same engine but with a 1″ shaft. An adapter is available from Amazon It can be bought much cheaper than the Honda and the muffler is standard while it is an additional price on the Honda. It’s now called a GX670 (22.1 hp rated).
Hello
Any idea of the battery needed here?
I have found that a small motorcycle battery would work for mine, as long as you have a charging system on your motor and it dosen’t take a lot of cranking to get your motor started.
WHAT OIL FILTER IS NEEDED?
I have a GX690 that overfills with fuel after running and then won’t start (Hydrolics) the engine and forces fuel down through the piston rings into the oil. any Ideas??
Needle valve and seat are not closing properly at the float… You should try taking apart the carb and give it a good cleaning.. most likely dirt is the culprit .. On YouTube there is a video for the Honda engine carb cleaning… https://www.youtube.com/watch?v=-IIGAsyT3Jc go check it out.
Fuel solenoid stuck open
It’s possible that those who put everything together didn’t realize the motor had it’s own fuel pump. The external pump shouldn’t hurt anything.
I have a GX 670 for sale on ebay if anyone is looking to buy.. it was a back up motor for a carpet cleaning machine. I only used it 2 days prob 8 hrs total use. I paid $1200 asking for $700 and u pay shippin. thanks! questions will be answerd on ebay guys take care.
Do you still have this engine
Send me the link im interested, 9094469949
i have tried 3 carbs runs if i put gas manul and yes fuel pump works what is my problem
Fuel shut off solenoid. Check your wiring and make sure it is properly grounded
I have a GX 670 motor on my small ride on loader
It goes ok then when I unbalance it it Starts to put out heaps of white smoke
Does any body know how the oil would get into the. Piston chamber
Thank you
Hi, I have a GX670 that smokes quite a bit blue/white burnt oil smoke especially with full throttle. So far I have tested compression both cylinders have 130 psi, new plugs, clean fuel, clean carb, no oil coming out of the breather hose, intake ports do not have oil, exhaust ports do not have oil (so the guides are not leaking), spark is good since the engine runs good BUT smokes. Changed oil and filter (not overfilled) for sure. Head gaskets are a suspect but with such awesome compression I am hesitant to pull it apart. Any suggestions would be much appreciated.
Does anybody know the horizontal shaft size of this motor
What is the out put shaft size?
I need a new Motor, How can i get one?
Hi can you help me with a oil filter and air filter
One Honda gx670 engine is available
Some of your carb issues are easy to fix … and may not need parts just a good cleaning. I have been working on my carb and it did not need parts all by watching a YouTube Video on Honda Carb cleaning https://www.youtube.com/watch?v=-IIGAsyT3Jc
I have a 2005 Club Car XRT 1500 with the Honda GX620 engine. I have access to a new GX670 that is currently propane. Can I put my intake and carb off mine and bolt is right back in? I’m told I have the tapered crankshaft as does this one. Would this be a direct bolt in or would I be better off just rebuilding mine?