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Suzuki DT20 two-stroke (1988) service guide

Oil, gear oil, spark plugs and the service schedule for the Suzuki DT20 two-stroke (1988) (20 hp, two-stroke), from the factory service manual, plus how we service it in Hawaiʻi.

Models covered: Model designation DT20 CESJ.

Quick answers

What two-stroke oil does a Suzuki DT20 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 DT20 two-stroke?
100:1 premix per the General Engine Specifications (1988).
What gear oil does a Suzuki DT20 two-stroke use, and how much?
Suzuki Outboard Motor Gear Oil or an equivalent high quality SAE 90 hypoid gear oil. Quantity: 10.1 oz (300 ml).
What spark plug does a Suzuki DT20 two-stroke use?
NGK BR7HS (Champion L5, L7J), 1988. Qty 2. Gap: 0.035 to 0.039 in (0.9 to 1.0 mm).
How often should a Suzuki DT20 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 DT20 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 DT20 two-stroke?
600 to 650 rpm.

Maintenance specs

Two-stroke oilSuzuki CCI oil or an NMMA certified 2-stroke lubricant; if neither is available, use only 2-stroke outboard oil
Fuel to oil mix100:1 premix per the General Engine Specifications (1988).
Gear oilSuzuki Outboard Motor Gear Oil or an equivalent high quality SAE 90 hypoid gear oil
Gear oil quantity10.1 oz (300 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 plugNGK BR7HS (Champion L5, L7J), 1988. Qty 2
Spark plug gap0.035 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 650 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.

  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 oil, gear case plug gaskets, propeller cotter pin

    Check: spark plugs, water pump impeller, anodes

  3. Every 100 hours or 6 months

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

    Check: spark plugs, water pump impeller, 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, 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.

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