Honda GX630 Engine Instruction Manual
Honda GX630 Engine
Honda GX630 Engine Instructions
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Honda GX630 Engine Specifications
| Feature | Specification |
|---|---|
| Model / Type | GX630 (QAF-Type) |
| Dimensions (L × W × H) | 405 × 410 × 438 mm (15.9 × 16.1 × 17.2 in) |
| Dry Mass [Weight] | 44.4 kg (97.9 lbs) |
| Engine Type | 4-stroke, overhead valve, 2 cylinders (90° V-Twin) |
| Displacement | 688.0 cm³ (41.97 cu-in) |
| Bore × Stroke | 78.0 × 72.0 mm (3.07 × 2.83 in) |
| Net Power (SAE J1349) | 15.5 kW (21.1 PS, 20.8 bhp) at 3,600 rpm |
| Max. Net Torque (SAE J1349) | 48.3 N·m (4.93 kgf·m, 35.6 lbf·ft) at 2,500 rpm |
| Engine Oil Capacity (without oil filter replacement) | 1.5 L (1.6 US qt, 1.3 Imp qt) |
| Engine Oil Capacity (with oil filter replacement) | 1.7 L (1.8 US qt, 1.5 Imp qt) |
| Cooling System | Forced air |
| Ignition System | CDI type magneto ignition |
| PTO Shaft Rotation | Counterclockwise |
| Recommended Fuel | Unleaded gasoline, pump octane 86 or higher (research octane 91 or higher) |
| Ethanol / Methanol Limit | Max. 10% ethanol (E10) or 5% methanol by volume |
| Recommended Engine Oil | SAE 10W-30 or 5W-30, API SJ or later |
| Cold-Weather Oil | Full synthetic 5W-30 for -15°C to -25°C (5°F to -13°F) |
| Spark Plug | ZFR5F (NGK) |
| Spark Plug Gap | 0.7–0.8 mm (0.028–0.031 in) |
| Idle Speed | 1,400 ± 150 rpm |
| Valve Clearance (cold) | IN: 0.08 ± 0.02 mm; EX: 0.10 ± 0.02 mm |
| Oil Filter Tightening Torque | 12 N·m (1.2 kgf·m, 9 lbf·ft) |
| Recommended Battery | 12 V – 36 Ah |
| Main Fuse | 30 A |
| Charge Coil Options | 2.7 A or 17 A (with or without control box) |
| Maximum Operating Slope | 20° |
Honda GX630 Engine Details
The Honda GX630 is a twin-cylinder V-Twin built for demanding commercial equipment, and its owner's manual covers it alongside the GX660 and GX690. The engine has several built-in protection systems. On applicable types, the Oil Alert system lights a red indicator and shuts the engine down automatically before the crankcase oil drops below a safe level. The engine switch stays in the ON position. If the engine stops and won't restart, check the oil level first.
A fuel-cut solenoid lets fuel reach the carburetor main jet only when the engine switch is in the ON or START position. Because the solenoid needs battery power, the engine has to stay connected to the battery to run. If the battery is disconnected while the engine is running, fuel stops flowing and the engine shuts down. Some versions also have an hour meter that counts only actual running time, not the time the switch is simply ON.
Starting the engine is simple. Pull the choke knob to CLOSED for a cold start, move the throttle about one third of the way toward MAX, and turn the key to START. Run the starter for no more than 5 seconds at a time, then wait at least 10 seconds before trying again so the motor doesn't overheat. Let the engine warm up for 2 to 3 minutes. Remote throttle and choke cables can be attached through holes in the control levers.
The maintenance schedule calls for checking the oil before each use and changing it after the first month or 20 hours, then every 100 hours. Replace the oil filter every 200 hours. Clean the dual-stage air cleaner, which has a foam pre-filter over a paper element, every 3 months or 50 hours. Replace the paper element every 300 hours. Valve clearance and idle speed are checked every 300 hours, and the combustion chamber is cleaned every 1,000 hours.
When you change the oil filter, use a filter socket rather than a strap wrench so you don't damage the oil pressure switch. Tighten the new filter by an extra 3/4 turn after the seal touches the base. Remove the spark plugs with a 5/8-inch wrench. Tighten a new plug 1/2 turn after it seats, or tighten a reused plug 1/8 to 1/4 turn. Clean the optional spark arrester every 100 hours. Some areas require one by law.
For high-altitude use above 1,500 meters (5,000 feet), the manual recommends having a dealer modify the carburetor. Even with the modification, power drops by about 3.5% for every 300 meters of altitude gained. Running a modified carburetor below that altitude can overheat the engine. The emission control system is certified to EPA, California and Canadian standards, and models sold in California carry an Air Index label showing their emissions durability period.
For storage, add a fuel stabilizer or drain the tank and carburetor. Change the oil and pour 5 to 10 cc of clean oil into each cylinder. Remove the battery and recharge it once a month. Let the engine cool for 15 minutes before transporting it. The 30 A fuse protects the starter relay and the charging circuits. It sits behind the switch box rear cover and should never be replaced with a fuse rated above 30 amperes.
Frequently Asked Questions (FAQs)
Can't find the answer you need? Here are some frequently asked questions about the Honda GX630 Engine, and we answer them below.
