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Suzuki DT115 / DT140 two-stroke (1988-2001, oil injected, carbureted or EFI) service guide

Oil, gear oil, spark plugs and the service schedule for the Suzuki DT115 / DT140 two-stroke (1988-2001, oil injected, carbureted or EFI) (115 to 140 hp, two-stroke), from the factory service manual, plus how we service it in Hawaiʻi.

Quick answers

What two-stroke oil does a Suzuki DT115 / DT140 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 DT115 / DT140 two-stroke?
Oil injection, variable ratio: about 150:1 fuel to oil at idle, changing gradually to 50:1 at full throttle.
What gear oil does a Suzuki DT115 / DT140 two-stroke use, and how much?
Suzuki Outboard Motor Gear Oil or an equivalent high quality SAE 90 hypoid gear oil. Quantity: 37.2 oz (1100 ml).
What spark plug does a Suzuki DT115 / DT140 two-stroke use?
1988-95: NGK B8HS (Champion L4J, RL4J, L78, RL78). 1996 carbureted: NGK BR8HCS-10. 1996-01 EFI: NGK BR8HS-10. Qty 4. Gap: 1988-90: 0.031 to 0.035 in (0.8 to 0.9 mm). 1991 on: 0.035 to 0.039 in (0.9 to 1.0 mm).
How often should a Suzuki DT115 / DT140 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 DT115 / DT140 two-stroke?
The factory schedule says to replace it at 100 hours, and we follow that. In any case we never let it go longer than a year in Hawaiʻi's salt water.
What is the idle speed of a Suzuki DT115 / DT140 two-stroke?
600 to 700 rpm; 650 to 750 rpm for the 1996 carbureted row.
What is the propeller nut torque on a Suzuki DT115 / DT140 two-stroke?
36 to 43.5 ft-lb (50 to 60 N·m).

Maintenance specs

Injection oilSuzuki CCI oil or an NMMA certified 2-stroke lubricant; if neither is available, use only 2-stroke outboard oil
Oil tank6.3 quarts (6.0 liters)
Fuel to oil ratioOil injection, variable ratio: about 150:1 fuel to oil at idle, changing gradually to 50:1 at full throttle
Gear oilSuzuki Outboard Motor Gear Oil or an equivalent high quality SAE 90 hypoid gear oil
Gear oil quantity37.2 oz (1100 ml)
Gear oil drain (fill) plug and oil level plugLoosen 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 test16 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 plug1988-95: NGK B8HS (Champion L4J, RL4J, L78, RL78). 1996 carbureted: NGK BR8HCS-10. 1996-01 EFI: NGK BR8HS-10. Qty 4
Spark plug gap1988-90: 0.031 to 0.035 in (0.8 to 0.9 mm). 1991 on: 0.035 to 0.039 in (0.9 to 1.0 mm)
Spark plug torque10 to 15 ft-lb (14 to 20 N·m) with a new crush washer, or about 1/4 turn to crush the washer.
Idle speed600 to 700 rpm; 650 to 750 rpm for the 1996 carbureted row
Propeller nut36 to 43.5 ft-lb (50 to 60 N·m)
Power trim and tiltPTT unit: tilt cylinder 94 ft-lb (130 N·m), trim cylinder 58 ft-lb (80 N·m).

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.

  1. First 10 hours or 1 month

    Replace: gear case oil, gear case plug gaskets, propeller cotter pin

  2. Every 50 hours or 3 months

    Replace: gear case plug gaskets

    Check: fuel filter, anodes

  3. Every 100 hours or 6 months

    Replace: gear case oil, gear case plug gaskets, propeller cotter pin, water pump impeller

    Check: spark plugs, fuel filter, anodes

  4. 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, fuel filter, anodes

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.

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