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Suzuki DT75 / DT85 two-stroke (1988-2000, oil injected) service guide

Oil, gear oil, spark plugs and the service schedule for the Suzuki DT75 / DT85 two-stroke (1988-2000, oil injected) (75 to 85 hp, two-stroke), from the factory service manual, plus how we service it in Hawaiʻi.

Models covered: DT75, 1988 to 1997, and DT85, 1988 to 2000: inline 3 cylinder, 73 cu in (1197 cc), bore and stroke 3.31 x 2.83 in, oil injection, Digital I.C. ignition, electric start with electric choke. Early engines have multi-point oil injection and an external power trim pump; later engines have single-point oil injection and an integrated PTT unit.

Quick answers

What two-stroke oil does a Suzuki DT75 / DT85 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 DT75 / DT85 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 DT75 / DT85 two-stroke use, and how much?
Suzuki Outboard Motor Gear Oil or an equivalent high quality SAE 90 hypoid gear oil. Quantity: 23.7 oz (700 ml).
What spark plug does a Suzuki DT75 / DT85 two-stroke use?
DT75 1988-94: NGK B8HS-10; DT75 1995-97: NGK BR8HS-10. DT85 1988-91: NGK B8HS; DT85 1992-94: NGK B8HS-10; DT85 1995-00: NGK BR8HS-10. Champion L4J, RL4J, L78, RL78 for the B8HS and B8HS-10 years. Qty 3. Gap: To 1994: 0.031 to 0.035 in (0.8 to 0.9 mm). 1995 on (BR8HS-10): 0.035 to 0.039 in (0.9 to 1.0 mm).
How often should a Suzuki DT75 / DT85 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 DT75 / DT85 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 DT75 / DT85 two-stroke?
To 1994: 600 to 700 rpm. 1995 on: 700 to 800 rpm.
What is the propeller nut torque on a Suzuki DT75 / DT85 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
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 quantity23.7 oz (700 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 plugDT75 1988-94: NGK B8HS-10; DT75 1995-97: NGK BR8HS-10. DT85 1988-91: NGK B8HS; DT85 1992-94: NGK B8HS-10; DT85 1995-00: NGK BR8HS-10. Champion L4J, RL4J, L78, RL78 for the B8HS and B8HS-10 years. Qty 3
Spark plug gapTo 1994: 0.031 to 0.035 in (0.8 to 0.9 mm). 1995 on (BR8HS-10): 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 speedTo 1994: 600 to 700 rpm. 1995 on: 700 to 800 rpm
Propeller nut36 to 43.5 ft-lb (50 to 60 N·m)
Power trim and tiltThe PTT system is pressurized: remove the fill plug only with the motor fully tilted and supported.

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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