Suzuki DT4 / DT5Y two-stroke (1988-2002, premix) service guide
Oil, gear oil, spark plugs and the service schedule for the Suzuki DT4 / DT5Y two-stroke (1988-2002, premix) (4 to 5 hp, two-stroke), from the factory service manual, plus how we service it in Hawaiʻi.
Models covered: DT4, 1988 to 1999: 1 cylinder, 5.5 cu in (90 cc), bore and stroke 1.97 x 1.81 in, premix, Suzuki P.E.I. ignition, manual start. DT5Y, 1998 to 2002: 1 cylinder, 6.7 cu in (109 cc), 2.2 x 1.8 in, premix, built on the DT4 platform with a larger bore, a different carburetor and a neutral start interlock on the recoil starter.
Quick answers
- What two-stroke oil does a Suzuki DT4 / DT5Y two-stroke use?
- Suzuki CCI oil or an NMMA certified 2-stroke lubricant; if neither is available, use only 2-stroke outboard oil.
- What is the fuel to oil ratio for a Suzuki DT4 / DT5Y two-stroke?
- DT4 1988 to 1997: 100:1 premix.
- What gear oil does a Suzuki DT4 / DT5Y two-stroke use, and how much?
- Suzuki Outboard Motor Gear Oil or an equivalent high quality SAE 90 hypoid gear oil. Quantity: 6.4 oz (190 ml), DT4 and DT5Y.
- What spark plug does a Suzuki DT4 / DT5Y two-stroke use?
- DT4 1988-89: NGK BP6HS (Champion RL12Y, RL87Y, L66Y); DT4 1990-98: NGK BP5HS (Champion L81, L88A); DT5Y 1998-02: NGK BPR7HS-10. Qty 1. Gap: DT4: 0.024 to 0.028 in (0.6 to 0.7 mm). DT5Y: 0.035 to 0.039 in (0.9 to 1.0 mm).
- How often should a Suzuki DT4 / DT5Y two-stroke be serviced?
- The factory schedule lists: First 10 hours or 1 month; Every 50 hours or 3 months; Every 100 hours or 6 months. 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 Suzuki DT4 / DT5Y two-stroke?
- The factory schedule says to inspect it at 50 hours and 100 hours. 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 Suzuki DT4 / DT5Y two-stroke?
- DT4: 850 to 900 rpm. DT5Y: 1150 to 1250 rpm.
Maintenance specs
| Two-stroke oil | Suzuki CCI oil or an NMMA certified 2-stroke lubricant; if neither is available, use only 2-stroke outboard oil |
|---|---|
| Fuel to oil mix | DT4 1988 to 1997: 100:1 premix. |
| Gear oil | Suzuki Outboard Motor Gear Oil or an equivalent high quality SAE 90 hypoid gear oil |
| Gear oil quantity | 6.4 oz (190 ml), DT4 and DT5Y |
| Gear oil drain (fill) plug and oil level plug | Loosen the oil level plug first, then remove the fill (drain) plug at the lower end of the gear housing, then the oil level plug. Check the magnet end of the drain screw for metal. Use new gaskets (washers); install the oil level and vent plugs (if fitted) first, then the fill plug. |
| Lower unit pressure test | 16 to 18 psi of air, submerged or sprayed with soapy water; then 3 to 5 inches of vacuum; hold each for a few minutes |
| Spark plug | DT4 1988-89: NGK BP6HS (Champion RL12Y, RL87Y, L66Y); DT4 1990-98: NGK BP5HS (Champion L81, L88A); DT5Y 1998-02: NGK BPR7HS-10. Qty 1 |
| Spark plug gap | DT4: 0.024 to 0.028 in (0.6 to 0.7 mm). DT5Y: 0.035 to 0.039 in (0.9 to 1.0 mm) |
| Spark plug torque | 10 to 15 ft-lb (14 to 20 N·m) with a new crush washer, or about 1/4 turn to crush the washer. |
| Idle speed | DT4: 850 to 900 rpm. DT5Y: 1150 to 1250 rpm |
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 10 hours or 1 month
Replace: gear case oil, gear case plug gaskets, propeller cotter pin
Every 50 hours or 3 months
Replace: gear case oil, gear case plug gaskets, propeller cotter pin
Check: spark plugs, water pump impeller, anodes
Every 100 hours or 6 months
Replace: gear case oil, gear case plug gaskets, propeller cotter pin
Check: spark plugs, water pump impeller, anodes
Every 200 hours or 1 year (our Hawai‘i yearly service) Hawai‘i
Replace: gear case oil, gear case plug gaskets, propeller cotter pin, water pump impeller
Check: spark plugs, anodes
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: Suzuki DT 2 to 225 hp two-stroke outboards service manual. Specs can change by model year and serial number, so always confirm your exact model from the serial tag on the clamp bracket.