Honda BF75A / BF90A service guide
Oil, gear oil, spark plugs and the service schedule for the Honda BF75A / BF90A (75 to 90 hp, four-stroke), from the factory service manual, plus how we service it in Hawaiʻi.
Models covered: BF75A (codes BBAL/BBAU) and BF90A (BBBL/BBBU); 4-stroke 4 cylinder, 1,590 cm³, 4 carburetors, CDI.
Quick answers
- How much oil does a Honda BF75A / BF90A take?
- 4.0 L (4.2 US qt); 4.5 L (4.8 US qt) with filter.
- What engine oil does a Honda BF75A / BF90A use?
- SAE 10W-30 or 10W-40, API SH.
- What gear oil does a Honda BF75A / BF90A use, and how much?
- Quicksilver Gear Lubricant or Quicksilver Super-Duty Lower Unit Lubricant. Quantity: 0.66 L (0.70 US qt).
- What spark plug does a Honda BF75A / BF90A use?
- NGK DR7EA or Nippondenso X22ESR-U, qty 4. Gap: 0.6 to 0.7 mm (0.024 to 0.028 in).
- How often should a Honda BF75A / BF90A be serviced?
- The factory schedule lists: First 20 hours or month; Every 100 hours or 6 months; Every 200 hours or year; Every 400 hours or 2 years. In Hawaiʻi's salt water we do a full yearly service every 200 hours or 1 year, whichever comes first, and a new engine needs its first (break-in) service.
- When should the water pump impeller be replaced on a Honda BF75A / BF90A?
- The factory schedule gives no replacement interval. In Hawaiʻi's warm salt water we replace it every 200 hours or 1 year, whichever comes first, because a worn impeller is the most common cause of overheating.
- What is the idle speed of a Honda BF75A / BF90A?
- 950 ± 50 r/min in neutral, warm.
- What is the propeller nut torque on a Honda BF75A / BF90A?
- 75 N·m (7.6 kgf·m, 55 lbf·ft) with tab washer; bend the tabs to lock.
Maintenance specs
| Engine oil | SAE 10W-30 or 10W-40, API SH |
|---|---|
| Engine oil quantity | 4.0 L (4.2 US qt); 4.5 L (4.8 US qt) with filter |
| Oil filter | Hand tight until the seal touches, then 7/8 turn more with wrench 07912-6110001; 22 N·m (2.2 kgf·m, 16 lbf·ft) |
| Engine oil drain plug | 23 N·m (2.3 kgf·m, 17 lbf·ft), new washer; drain plug cover screw 6 x 35: 6.4 N·m (4.7 lbf·ft) |
| Gear oil | Quicksilver Gear Lubricant or Quicksilver Super-Duty Lower Unit Lubricant |
| Gear oil quantity | 0.66 L (0.70 US qt) |
| Gear oil drain, level and vent screws | 7 N·m (0.7 kgf·m, 5.1 lbf·ft); fill from the drain hole, put the level and vent screws in first, then the drain screw |
| Spark plug | NGK DR7EA or Nippondenso X22ESR-U, qty 4 |
| Spark plug gap | 0.6 to 0.7 mm (0.024 to 0.028 in) |
| Spark plug tightening | New plug 1/2 turn after seating; reused plug 1/8 to 1/4 turn after seating |
| Idle speed | 950 ± 50 r/min in neutral, warm |
| Thermostat | Starts opening 72 °C (162 °F); fully open 82 °C (180 °F); lift more than 3.0 mm (0.12 in) |
| Anode nut | M6: 7 N·m (0.7 kgf·m, 5.1 lbf·ft) |
| Propeller shaft nut | 75 N·m (7.6 kgf·m, 55 lbf·ft) with tab washer; bend the tabs to lock |
| Valve clearance, cold | IN 0.18 to 0.22 mm (0.007 to 0.009 in); EX 0.26 to 0.30 mm (0.010 to 0.012 in); lock nut 23 N·m (2.3 kgf·m, 17 lbf·ft) |
| Timing belt | Automatic tensioner; inspect, replace if worn or damaged; do not push the tensioner toward the belt. Tensioner bolt 10 x 45: 44 N·m (33 lbf·ft); driven pulley bolt 56 N·m (41 lbf·ft) |
Service schedule
The factory maintenance intervals, with what is replaced and what is checked at each. Rows marked Hawaiʻi are our shop's yearly service for salt water use.
First 20 hours or month
Replace: engine oil, oil drain plug gasket, gear case oil, gear case plug gaskets
Check: spark plugs
Every 100 hours or 6 months
Replace: engine oil, oil drain plug gasket, gear case plug gaskets
Check: fuel filter, gear case oil
Every 200 hours or year
Replace: engine oil, oil filter, oil drain plug gasket, gear case oil, gear case plug gaskets, water pump impeller
Check: spark plugs, fuel filter, thermostat
Every 400 hours or 2 years
Replace: engine oil, oil filter, oil drain plug gasket, fuel filter, gear case oil, gear case plug gaskets, water pump impeller
Check: spark plugs, thermostat
We replace the water pump impeller at every service from 200 hours up, which can be sooner than the factory schedule, because of Hawaiʻi’s warm salt water.
Source: Honda BF75A/BF90A Shop Manual, part no. 66ZW000. Specs can change by model year and serial number, so always confirm your exact model from the serial tag on the clamp bracket.