Honda BF25D / BF30D service guide
Oil, gear oil, spark plugs and the service schedule for the Honda BF25D / BF30D (25 to 30 hp, four-stroke), from the factory service manual, plus how we service it in Hawaiʻi.
Models covered: BF25D (code BEATJ) types SH, LH, LG, SG, SHG, LHG, LHT, SRT, LRT; BF30D (BEAUJ) types SH, LH, LG, SG, SHG, LHG, SHT, SRT, LHT, LRT; 4-stroke 3 cylinder OHC, 552 cm³, 3 carburetors, digital CDI.
Quick answers
- How much oil does a Honda BF25D / BF30D take?
- 1.6 L (1.69 US qt) oil change; 1.9 L (2.01 US qt) with filter.
- What gear oil does a Honda BF25D / BF30D use, and how much?
- Marine SAE 90 hypoid gear oil, API GL-4 or GL-5. Quantity: 0.27 L (0.29 US qt) in the BF25D/BF30D specs.
- What spark plug does a Honda BF25D / BF30D use?
- NGK DR7EA or Denso X22ESR-U, qty 3. Gap: 0.6 to 0.7 mm (0.024 to 0.028 in).
- How often should a Honda BF25D / BF30D be serviced?
- The factory schedule lists: First month or 20 hours; Every 6 months or 100 hours; Every year or 200 hours; Every 2 years or 400 hours. 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 BF25D / BF30D?
- 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 BF25D / BF30D?
- 950 ± 50 r/min in neutral.
- What is the propeller nut torque on a Honda BF25D / BF30D?
- 1 N·m (0.1 kgf·m), then tighten until the split pin fits. New cotter pin.
Maintenance specs
| Engine oil quantity | 1.6 L (1.69 US qt) oil change; 1.9 L (2.01 US qt) with filter |
|---|---|
| Oil filter | Hand tight, then 11 N·m (1.1 kgf·m, 8 lbf·ft) with wrench 07HAA-PJ70100 |
| Engine oil drain plug | 23 N·m (2.3 kgf·m, 17 lbf·ft), M12 x 1.5, new sealing washer |
| Gear oil | Marine SAE 90 hypoid gear oil, API GL-4 or GL-5 |
| Gear oil quantity | 0.27 L (0.29 US qt) in the BF25D/BF30D specs |
| Gear oil drain and check plugs | Check bolt 3.5 N·m (2.5 lbf·ft); drain plug 3.4 N·m (2.5 lbf·ft); New washers; level plug in first, then drain plug |
| Spark plug | NGK DR7EA or Denso X22ESR-U, qty 3 |
| Spark plug gap | 0.6 to 0.7 mm (0.024 to 0.028 in) |
| Spark plug torque | 18 N·m (1.8 kgf·m, 13 lbf·ft). Base procedure: new plug 1/2 turn after seating, reused 1/8 to 1/4 turn |
| Idle speed | 950 ± 50 r/min in neutral |
| Thermostat | Starts opening 60 °C, fully open 70 °C, stamped 60 °C (the BF25A/30A part was 72 / 82 °C). |
| Propeller castle nut | 1 N·m (0.1 kgf·m), then tighten until the split pin fits. New cotter pin. |
| Valve clearance, cold | IN 0.10 to 0.14 mm; EX 0.18 to 0.22 mm; lock nut 8 N·m (0.8 kgf·m, 5.8 lbf·ft) |
| Timing belt | Inspect the full length, replace if worn or damaged (base 3-15); tensioner bolt 44 N·m (4.5 kgf·m, 33 lbf·ft); adjusting spring bolt 12 N·m (9 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 month or 20 hours
Replace: engine oil, oil drain plug gasket, gear case oil, gear case plug gaskets
Every 6 months or 100 hours
Replace: engine oil, oil drain plug gasket, gear case oil, gear case plug gaskets
Check: spark plugs, fuel filter
Every year or 200 hours
Replace: engine oil, oil filter, oil drain plug gasket, spark plugs, gear case oil, gear case plug gaskets, water pump impeller
Check: fuel filter, thermostat
Every 2 years or 400 hours
Replace: engine oil, oil filter, oil drain plug gasket, spark plugs, fuel filter, gear case oil, gear case plug gaskets, water pump impeller
Check: 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 BF25D/BF30D Shop Manual Supplement. Specs can change by model year and serial number, so always confirm your exact model from the serial tag on the clamp bracket.